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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * CFQ, or complete fairness queueing, disk scheduler.
3 *
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6 *
Jens Axboe0fe23472006-09-04 15:41:16 +02007 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090010#include <linux/slab.h>
Al Viro1cc9be62006-03-18 12:29:52 -050011#include <linux/blkdev.h>
12#include <linux/elevator.h>
Randy Dunlapad5ebd22009-11-11 13:47:45 +010013#include <linux/jiffies.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/rbtree.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020015#include <linux/ioprio.h>
Jens Axboe7b679132008-05-30 12:23:07 +020016#include <linux/blktrace_api.h>
Tejun Heo6e736be2011-12-14 00:33:38 +010017#include "blk.h"
Vivek Goyale98ef892010-06-18 10:39:47 -040018#include "cfq.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
20/*
21 * tunables
22 */
Jens Axboefe094d92008-01-31 13:08:54 +010023/* max queue in one round of service */
Shaohua Liabc3c742010-03-01 09:20:54 +010024static const int cfq_quantum = 8;
Arjan van de Ven64100092006-01-06 09:46:02 +010025static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
Jens Axboefe094d92008-01-31 13:08:54 +010026/* maximum backwards seek, in KiB */
27static const int cfq_back_max = 16 * 1024;
28/* penalty of a backwards seek */
29static const int cfq_back_penalty = 2;
Arjan van de Ven64100092006-01-06 09:46:02 +010030static const int cfq_slice_sync = HZ / 10;
Jens Axboe3b181522005-06-27 10:56:24 +020031static int cfq_slice_async = HZ / 25;
Arjan van de Ven64100092006-01-06 09:46:02 +010032static const int cfq_slice_async_rq = 2;
Jens Axboecaaa5f92006-06-16 11:23:00 +020033static int cfq_slice_idle = HZ / 125;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +020034static int cfq_group_idle = HZ / 125;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +010035static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
36static const int cfq_hist_divisor = 4;
Jens Axboe22e2c502005-06-27 10:55:12 +020037
Jens Axboed9e76202007-04-20 14:27:50 +020038/*
Jens Axboe08717142008-01-28 11:38:15 +010039 * offset from end of service tree
Jens Axboed9e76202007-04-20 14:27:50 +020040 */
Jens Axboe08717142008-01-28 11:38:15 +010041#define CFQ_IDLE_DELAY (HZ / 5)
Jens Axboed9e76202007-04-20 14:27:50 +020042
43/*
44 * below this threshold, we consider thinktime immediate
45 */
46#define CFQ_MIN_TT (2)
47
Jens Axboe22e2c502005-06-27 10:55:12 +020048#define CFQ_SLICE_SCALE (5)
Aaron Carroll45333d52008-08-26 15:52:36 +020049#define CFQ_HW_QUEUE_MIN (5)
Vivek Goyal25bc6b02009-12-03 12:59:43 -050050#define CFQ_SERVICE_SHIFT 12
Jens Axboe22e2c502005-06-27 10:55:12 +020051
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +010052#define CFQQ_SEEK_THR (sector_t)(8 * 100)
Shaohua Lie9ce3352010-03-19 08:03:04 +010053#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
Corrado Zoccolo41647e72010-02-27 19:45:40 +010054#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +010055#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
Shaohua Liae54abe2010-02-05 13:11:45 +010056
Tejun Heoa612fdd2011-12-14 00:33:41 +010057#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
58#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
59#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Christoph Lametere18b8902006-12-06 20:33:20 -080061static struct kmem_cache *cfq_pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Jens Axboe22e2c502005-06-27 10:55:12 +020063#define CFQ_PRIO_LISTS IOPRIO_BE_NR
64#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
Jens Axboe22e2c502005-06-27 10:55:12 +020065#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
66
Jens Axboe206dc692006-03-28 13:03:44 +020067#define sample_valid(samples) ((samples) > 80)
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -050068#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
Jens Axboe206dc692006-03-28 13:03:44 +020069
Tejun Heoc5869802011-12-14 00:33:41 +010070struct cfq_ttime {
71 unsigned long last_end_request;
72
73 unsigned long ttime_total;
74 unsigned long ttime_samples;
75 unsigned long ttime_mean;
76};
77
Jens Axboe22e2c502005-06-27 10:55:12 +020078/*
Jens Axboecc09e292007-04-26 12:53:50 +020079 * Most of our rbtree usage is for sorting with min extraction, so
80 * if we cache the leftmost node we don't have to walk down the tree
81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
82 * move this into the elevator for the rq sorting as well.
83 */
84struct cfq_rb_root {
85 struct rb_root rb;
86 struct rb_node *left;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +010087 unsigned count;
Richard Kennedy73e9ffd2010-03-01 10:50:20 +010088 unsigned total_weight;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -050089 u64 min_vdisktime;
Shaohua Lif5f2b6c2011-07-12 14:24:55 +020090 struct cfq_ttime ttime;
Jens Axboecc09e292007-04-26 12:53:50 +020091};
Shaohua Lif5f2b6c2011-07-12 14:24:55 +020092#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
93 .ttime = {.last_end_request = jiffies,},}
Jens Axboecc09e292007-04-26 12:53:50 +020094
95/*
Jens Axboe6118b702009-06-30 09:34:12 +020096 * Per process-grouping structure
97 */
98struct cfq_queue {
99 /* reference count */
Shaohua Li30d7b942011-01-07 08:46:59 +0100100 int ref;
Jens Axboe6118b702009-06-30 09:34:12 +0200101 /* various state flags, see below */
102 unsigned int flags;
103 /* parent cfq_data */
104 struct cfq_data *cfqd;
105 /* service_tree member */
106 struct rb_node rb_node;
107 /* service_tree key */
108 unsigned long rb_key;
109 /* prio tree member */
110 struct rb_node p_node;
111 /* prio tree root we belong to, if any */
112 struct rb_root *p_root;
113 /* sorted list of pending requests */
114 struct rb_root sort_list;
115 /* if fifo isn't expired, next request to serve */
116 struct request *next_rq;
117 /* requests queued in sort_list */
118 int queued[2];
119 /* currently allocated requests */
120 int allocated[2];
121 /* fifo list of requests in sort_list */
122 struct list_head fifo;
123
Vivek Goyaldae739e2009-12-03 12:59:45 -0500124 /* time when queue got scheduled in to dispatch first request. */
125 unsigned long dispatch_start;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500126 unsigned int allocated_slice;
Richard Kennedyc4081ba2010-02-22 13:49:24 +0100127 unsigned int slice_dispatch;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500128 /* time when first request from queue completed and slice started. */
129 unsigned long slice_start;
Jens Axboe6118b702009-06-30 09:34:12 +0200130 unsigned long slice_end;
131 long slice_resid;
Jens Axboe6118b702009-06-30 09:34:12 +0200132
Christoph Hellwig65299a32011-08-23 14:50:29 +0200133 /* pending priority requests */
134 int prio_pending;
Jens Axboe6118b702009-06-30 09:34:12 +0200135 /* number of requests that are on the dispatch list or inside driver */
136 int dispatched;
137
138 /* io prio of this group */
139 unsigned short ioprio, org_ioprio;
Justin TerAvest4aede842011-07-12 08:31:45 +0200140 unsigned short ioprio_class;
Jens Axboe6118b702009-06-30 09:34:12 +0200141
Richard Kennedyc4081ba2010-02-22 13:49:24 +0100142 pid_t pid;
143
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +0100144 u32 seek_history;
Jeff Moyerb2c18e12009-10-23 17:14:49 -0400145 sector_t last_request_pos;
146
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +0100147 struct cfq_rb_root *service_tree;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -0400148 struct cfq_queue *new_cfqq;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500149 struct cfq_group *cfqg;
Vivek Goyalc4e78932010-08-23 12:25:03 +0200150 /* Number of sectors dispatched from queue in single dispatch round */
151 unsigned long nr_sectors;
Jens Axboe6118b702009-06-30 09:34:12 +0200152};
153
154/*
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100155 * First index in the service_trees.
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100156 * IDLE is handled separately, so it has negative index
157 */
158enum wl_prio_t {
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100159 BE_WORKLOAD = 0,
Vivek Goyal615f0252009-12-03 12:59:39 -0500160 RT_WORKLOAD = 1,
161 IDLE_WORKLOAD = 2,
Vivek Goyalb4627322010-10-22 09:48:43 +0200162 CFQ_PRIO_NR,
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100163};
164
165/*
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100166 * Second index in the service_trees.
167 */
168enum wl_type_t {
169 ASYNC_WORKLOAD = 0,
170 SYNC_NOIDLE_WORKLOAD = 1,
171 SYNC_WORKLOAD = 2
172};
173
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500174/* This is per cgroup per device grouping structure */
175struct cfq_group {
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500176 /* group service_tree member */
177 struct rb_node rb_node;
178
179 /* group service_tree key */
180 u64 vdisktime;
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500181 unsigned int weight;
Justin TerAvest8184f932011-03-17 16:12:36 +0100182 unsigned int new_weight;
183 bool needs_update;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500184
185 /* number of cfqq currently on this group */
186 int nr_cfqq;
187
Jens Axboe22e2c502005-06-27 10:55:12 +0200188 /*
Kyungmin Park4495a7d2011-05-31 10:04:09 +0200189 * Per group busy queues average. Useful for workload slice calc. We
Vivek Goyalb4627322010-10-22 09:48:43 +0200190 * create the array for each prio class but at run time it is used
191 * only for RT and BE class and slot for IDLE class remains unused.
192 * This is primarily done to avoid confusion and a gcc warning.
193 */
194 unsigned int busy_queues_avg[CFQ_PRIO_NR];
195 /*
196 * rr lists of queues with requests. We maintain service trees for
197 * RT and BE classes. These trees are subdivided in subclasses
198 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
199 * class there is no subclassification and all the cfq queues go on
200 * a single tree service_tree_idle.
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100201 * Counts are embedded in the cfq_rb_root
Jens Axboe22e2c502005-06-27 10:55:12 +0200202 */
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100203 struct cfq_rb_root service_trees[2][3];
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100204 struct cfq_rb_root service_tree_idle;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500205
206 unsigned long saved_workload_slice;
207 enum wl_type_t saved_workload;
208 enum wl_prio_t saved_serving_prio;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500209 struct blkio_group blkg;
210#ifdef CONFIG_CFQ_GROUP_IOSCHED
211 struct hlist_node cfqd_node;
Shaohua Li329a6782011-01-07 08:48:28 +0100212 int ref;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500213#endif
Vivek Goyal80bdf0c2010-08-23 12:24:26 +0200214 /* number of requests that are on the dispatch list or inside driver */
215 int dispatched;
Shaohua Li7700fc42011-07-12 14:24:56 +0200216 struct cfq_ttime ttime;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500217};
218
Tejun Heoc5869802011-12-14 00:33:41 +0100219struct cfq_io_cq {
220 struct io_cq icq; /* must be the first member */
221 struct cfq_queue *cfqq[2];
222 struct cfq_ttime ttime;
223};
224
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500225/*
226 * Per block device queue structure
227 */
228struct cfq_data {
229 struct request_queue *queue;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500230 /* Root service tree for cfq_groups */
231 struct cfq_rb_root grp_service_tree;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500232 struct cfq_group root_group;
233
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100234 /*
235 * The priority currently being served
236 */
237 enum wl_prio_t serving_prio;
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100238 enum wl_type_t serving_type;
239 unsigned long workload_expires;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500240 struct cfq_group *serving_group;
Jens Axboea36e71f2009-04-15 12:15:11 +0200241
242 /*
243 * Each priority tree is sorted by next_request position. These
244 * trees are used when determining if two or more queues are
245 * interleaving requests (see cfq_close_cooperator).
246 */
247 struct rb_root prio_trees[CFQ_PRIO_LISTS];
248
Jens Axboe22e2c502005-06-27 10:55:12 +0200249 unsigned int busy_queues;
Shaohua Lief8a41d2011-03-07 09:26:29 +0100250 unsigned int busy_sync_queues;
Jens Axboe22e2c502005-06-27 10:55:12 +0200251
Corrado Zoccolo53c583d2010-02-28 19:45:05 +0100252 int rq_in_driver;
253 int rq_in_flight[2];
Aaron Carroll45333d52008-08-26 15:52:36 +0200254
255 /*
256 * queue-depth detection
257 */
258 int rq_queued;
Jens Axboe25776e32006-06-01 10:12:26 +0200259 int hw_tag;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +0100260 /*
261 * hw_tag can be
262 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
263 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
264 * 0 => no NCQ
265 */
266 int hw_tag_est_depth;
267 unsigned int hw_tag_samples;
Jens Axboe22e2c502005-06-27 10:55:12 +0200268
269 /*
Jens Axboe22e2c502005-06-27 10:55:12 +0200270 * idle window management
271 */
272 struct timer_list idle_slice_timer;
Jens Axboe23e018a2009-10-05 08:52:35 +0200273 struct work_struct unplug_work;
Jens Axboe22e2c502005-06-27 10:55:12 +0200274
275 struct cfq_queue *active_queue;
Tejun Heoc5869802011-12-14 00:33:41 +0100276 struct cfq_io_cq *active_cic;
Jens Axboe22e2c502005-06-27 10:55:12 +0200277
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +0200278 /*
279 * async queue for each priority case
280 */
281 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
282 struct cfq_queue *async_idle_cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +0200283
Jens Axboe6d048f52007-04-25 12:44:27 +0200284 sector_t last_position;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 /*
287 * tunables, see top of file
288 */
289 unsigned int cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +0200290 unsigned int cfq_fifo_expire[2];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 unsigned int cfq_back_penalty;
292 unsigned int cfq_back_max;
Jens Axboe22e2c502005-06-27 10:55:12 +0200293 unsigned int cfq_slice[2];
294 unsigned int cfq_slice_async_rq;
295 unsigned int cfq_slice_idle;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +0200296 unsigned int cfq_group_idle;
Jens Axboe963b72f2009-10-03 19:42:18 +0200297 unsigned int cfq_latency;
Al Virod9ff4182006-03-18 13:51:22 -0500298
Jens Axboe6118b702009-06-30 09:34:12 +0200299 /*
300 * Fallback dummy cfqq for extreme OOM conditions
301 */
302 struct cfq_queue oom_cfqq;
Vivek Goyal365722b2009-10-03 15:21:27 +0200303
Corrado Zoccolo573412b2009-12-06 11:48:52 +0100304 unsigned long last_delayed_sync;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500305
306 /* List of cfq groups being managed on this device*/
307 struct hlist_head cfqg_list;
Vivek Goyal56edf7d2011-05-19 15:38:22 -0400308
309 /* Number of groups which are on blkcg->blkg_list */
310 unsigned int nr_blkcg_linked_grps;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311};
312
Vivek Goyal25fb5162009-12-03 12:59:46 -0500313static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
314
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500315static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
316 enum wl_prio_t prio,
Vivek Goyal65b32a52009-12-16 17:52:59 -0500317 enum wl_type_t type)
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100318{
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500319 if (!cfqg)
320 return NULL;
321
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100322 if (prio == IDLE_WORKLOAD)
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500323 return &cfqg->service_tree_idle;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100324
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500325 return &cfqg->service_trees[prio][type];
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100326}
327
Jens Axboe3b181522005-06-27 10:56:24 +0200328enum cfqq_state_flags {
Jens Axboeb0b8d7492007-01-19 11:35:30 +1100329 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
330 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
Jens Axboeb0291952009-04-07 11:38:31 +0200331 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
Jens Axboeb0b8d7492007-01-19 11:35:30 +1100332 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
Jens Axboeb0b8d7492007-01-19 11:35:30 +1100333 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
334 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
335 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
Jens Axboe44f7c162007-01-19 11:51:58 +1100336 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
Vasily Tarasov91fac312007-04-25 12:29:51 +0200337 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
Jeff Moyerb3b6d042009-10-23 17:14:51 -0400338 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
Shaohua Liae54abe2010-02-05 13:11:45 +0100339 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
Corrado Zoccolo76280af2009-11-26 10:02:58 +0100340 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
Vivek Goyalf75edf22009-12-03 12:59:53 -0500341 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
Jens Axboe3b181522005-06-27 10:56:24 +0200342};
343
344#define CFQ_CFQQ_FNS(name) \
345static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
346{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100347 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200348} \
349static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
350{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100351 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200352} \
353static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
354{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100355 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
Jens Axboe3b181522005-06-27 10:56:24 +0200356}
357
358CFQ_CFQQ_FNS(on_rr);
359CFQ_CFQQ_FNS(wait_request);
Jens Axboeb0291952009-04-07 11:38:31 +0200360CFQ_CFQQ_FNS(must_dispatch);
Jens Axboe3b181522005-06-27 10:56:24 +0200361CFQ_CFQQ_FNS(must_alloc_slice);
Jens Axboe3b181522005-06-27 10:56:24 +0200362CFQ_CFQQ_FNS(fifo_expire);
363CFQ_CFQQ_FNS(idle_window);
364CFQ_CFQQ_FNS(prio_changed);
Jens Axboe44f7c162007-01-19 11:51:58 +1100365CFQ_CFQQ_FNS(slice_new);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200366CFQ_CFQQ_FNS(sync);
Jens Axboea36e71f2009-04-15 12:15:11 +0200367CFQ_CFQQ_FNS(coop);
Shaohua Liae54abe2010-02-05 13:11:45 +0100368CFQ_CFQQ_FNS(split_coop);
Corrado Zoccolo76280af2009-11-26 10:02:58 +0100369CFQ_CFQQ_FNS(deep);
Vivek Goyalf75edf22009-12-03 12:59:53 -0500370CFQ_CFQQ_FNS(wait_busy);
Jens Axboe3b181522005-06-27 10:56:24 +0200371#undef CFQ_CFQQ_FNS
372
Vivek Goyalafc24d42010-04-26 19:27:56 +0200373#ifdef CONFIG_CFQ_GROUP_IOSCHED
Vivek Goyal2868ef72009-12-03 12:59:48 -0500374#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
375 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
376 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
Kyungmin Park4495a7d2011-05-31 10:04:09 +0200377 blkg_path(&(cfqq)->cfqg->blkg), ##args)
Vivek Goyal2868ef72009-12-03 12:59:48 -0500378
379#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
380 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
Kyungmin Park4495a7d2011-05-31 10:04:09 +0200381 blkg_path(&(cfqg)->blkg), ##args) \
Vivek Goyal2868ef72009-12-03 12:59:48 -0500382
383#else
Jens Axboe7b679132008-05-30 12:23:07 +0200384#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
385 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
Kyungmin Park4495a7d2011-05-31 10:04:09 +0200386#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
Vivek Goyal2868ef72009-12-03 12:59:48 -0500387#endif
Jens Axboe7b679132008-05-30 12:23:07 +0200388#define cfq_log(cfqd, fmt, args...) \
389 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
390
Vivek Goyal615f0252009-12-03 12:59:39 -0500391/* Traverses through cfq group service trees */
392#define for_each_cfqg_st(cfqg, i, j, st) \
393 for (i = 0; i <= IDLE_WORKLOAD; i++) \
394 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
395 : &cfqg->service_tree_idle; \
396 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
397 (i == IDLE_WORKLOAD && j == 0); \
398 j++, st = i < IDLE_WORKLOAD ? \
399 &cfqg->service_trees[i][j]: NULL) \
400
Shaohua Lif5f2b6c2011-07-12 14:24:55 +0200401static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
402 struct cfq_ttime *ttime, bool group_idle)
403{
404 unsigned long slice;
405 if (!sample_valid(ttime->ttime_samples))
406 return false;
407 if (group_idle)
408 slice = cfqd->cfq_group_idle;
409 else
410 slice = cfqd->cfq_slice_idle;
411 return ttime->ttime_mean > slice;
412}
Vivek Goyal615f0252009-12-03 12:59:39 -0500413
Vivek Goyal02b35082010-08-23 12:23:53 +0200414static inline bool iops_mode(struct cfq_data *cfqd)
415{
416 /*
417 * If we are not idling on queues and it is a NCQ drive, parallel
418 * execution of requests is on and measuring time is not possible
419 * in most of the cases until and unless we drive shallower queue
420 * depths and that becomes a performance bottleneck. In such cases
421 * switch to start providing fairness in terms of number of IOs.
422 */
423 if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
424 return true;
425 else
426 return false;
427}
428
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100429static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
430{
431 if (cfq_class_idle(cfqq))
432 return IDLE_WORKLOAD;
433 if (cfq_class_rt(cfqq))
434 return RT_WORKLOAD;
435 return BE_WORKLOAD;
436}
437
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100438
439static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
440{
441 if (!cfq_cfqq_sync(cfqq))
442 return ASYNC_WORKLOAD;
443 if (!cfq_cfqq_idle_window(cfqq))
444 return SYNC_NOIDLE_WORKLOAD;
445 return SYNC_WORKLOAD;
446}
447
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500448static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
449 struct cfq_data *cfqd,
450 struct cfq_group *cfqg)
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100451{
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500452 if (wl == IDLE_WORKLOAD)
453 return cfqg->service_tree_idle.count;
454
455 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
456 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
457 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100458}
459
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500460static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
461 struct cfq_group *cfqg)
462{
463 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
464 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
465}
466
Jens Axboe165125e2007-07-24 09:28:11 +0200467static void cfq_dispatch_insert(struct request_queue *, struct request *);
Jens Axboea6151c32009-10-07 20:02:57 +0200468static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
Jens Axboefd0928d2008-01-24 08:52:45 +0100469 struct io_context *, gfp_t);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200470
Tejun Heoc5869802011-12-14 00:33:41 +0100471static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
472{
473 /* cic->icq is the first member, %NULL will convert to %NULL */
474 return container_of(icq, struct cfq_io_cq, icq);
475}
476
Tejun Heo47fdd4c2011-12-14 00:33:42 +0100477static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
478 struct io_context *ioc)
479{
480 if (ioc)
481 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
482 return NULL;
483}
484
Tejun Heoc5869802011-12-14 00:33:41 +0100485static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200486{
Jens Axboea6151c32009-10-07 20:02:57 +0200487 return cic->cfqq[is_sync];
Vasily Tarasov91fac312007-04-25 12:29:51 +0200488}
489
Tejun Heoc5869802011-12-14 00:33:41 +0100490static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
491 bool is_sync)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200492{
Jens Axboea6151c32009-10-07 20:02:57 +0200493 cic->cfqq[is_sync] = cfqq;
Vasily Tarasov91fac312007-04-25 12:29:51 +0200494}
495
Tejun Heoc5869802011-12-14 00:33:41 +0100496static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +0400497{
Tejun Heoc5869802011-12-14 00:33:41 +0100498 return cic->icq.q->elevator->elevator_data;
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +0400499}
500
Vasily Tarasov91fac312007-04-25 12:29:51 +0200501/*
502 * We regard a request as SYNC, if it's either a read or has the SYNC bit
503 * set (in which case it could also be direct WRITE).
504 */
Jens Axboea6151c32009-10-07 20:02:57 +0200505static inline bool cfq_bio_sync(struct bio *bio)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200506{
Christoph Hellwig7b6d91d2010-08-07 18:20:39 +0200507 return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200508}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510/*
Andrew Morton99f95e52005-06-27 20:14:05 -0700511 * scheduler run of queue, if there are requests pending and no one in the
512 * driver that will restart queueing
513 */
Jens Axboe23e018a2009-10-05 08:52:35 +0200514static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
Andrew Morton99f95e52005-06-27 20:14:05 -0700515{
Jens Axboe7b679132008-05-30 12:23:07 +0200516 if (cfqd->busy_queues) {
517 cfq_log(cfqd, "schedule dispatch");
Jens Axboe23e018a2009-10-05 08:52:35 +0200518 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
Jens Axboe7b679132008-05-30 12:23:07 +0200519 }
Andrew Morton99f95e52005-06-27 20:14:05 -0700520}
521
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522/*
Jens Axboe44f7c162007-01-19 11:51:58 +1100523 * Scale schedule slice based on io priority. Use the sync time slice only
524 * if a queue is marked sync and has sync io queued. A sync queue with async
525 * io only, should not get full sync slice length.
526 */
Jens Axboea6151c32009-10-07 20:02:57 +0200527static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
Jens Axboed9e76202007-04-20 14:27:50 +0200528 unsigned short prio)
529{
530 const int base_slice = cfqd->cfq_slice[sync];
531
532 WARN_ON(prio >= IOPRIO_BE_NR);
533
534 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
535}
536
Jens Axboe44f7c162007-01-19 11:51:58 +1100537static inline int
538cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
539{
Jens Axboed9e76202007-04-20 14:27:50 +0200540 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
Jens Axboe44f7c162007-01-19 11:51:58 +1100541}
542
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500543static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
544{
545 u64 d = delta << CFQ_SERVICE_SHIFT;
546
547 d = d * BLKIO_WEIGHT_DEFAULT;
548 do_div(d, cfqg->weight);
549 return d;
550}
551
552static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
553{
554 s64 delta = (s64)(vdisktime - min_vdisktime);
555 if (delta > 0)
556 min_vdisktime = vdisktime;
557
558 return min_vdisktime;
559}
560
561static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
562{
563 s64 delta = (s64)(vdisktime - min_vdisktime);
564 if (delta < 0)
565 min_vdisktime = vdisktime;
566
567 return min_vdisktime;
568}
569
570static void update_min_vdisktime(struct cfq_rb_root *st)
571{
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500572 struct cfq_group *cfqg;
573
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500574 if (st->left) {
575 cfqg = rb_entry_cfqg(st->left);
Gui Jianfenga6032712011-03-07 09:28:09 +0100576 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
577 cfqg->vdisktime);
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500578 }
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500579}
580
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100581/*
582 * get averaged number of queues of RT/BE priority.
583 * average is updated, with a formula that gives more weight to higher numbers,
584 * to quickly follows sudden increases and decrease slowly
585 */
586
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500587static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
588 struct cfq_group *cfqg, bool rt)
Jens Axboe5869619c2009-10-28 09:27:07 +0100589{
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100590 unsigned min_q, max_q;
591 unsigned mult = cfq_hist_divisor - 1;
592 unsigned round = cfq_hist_divisor / 2;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500593 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100594
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500595 min_q = min(cfqg->busy_queues_avg[rt], busy);
596 max_q = max(cfqg->busy_queues_avg[rt], busy);
597 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100598 cfq_hist_divisor;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500599 return cfqg->busy_queues_avg[rt];
600}
601
602static inline unsigned
603cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
604{
605 struct cfq_rb_root *st = &cfqd->grp_service_tree;
606
607 return cfq_target_latency * cfqg->weight / st->total_weight;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100608}
609
Shaohua Lic553f8e2011-01-14 08:41:03 +0100610static inline unsigned
Vivek Goyalba5bd522011-01-19 08:25:02 -0700611cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe44f7c162007-01-19 11:51:58 +1100612{
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100613 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
614 if (cfqd->cfq_latency) {
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500615 /*
616 * interested queues (we consider only the ones with the same
617 * priority class in the cfq group)
618 */
619 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
620 cfq_class_rt(cfqq));
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100621 unsigned sync_slice = cfqd->cfq_slice[1];
622 unsigned expect_latency = sync_slice * iq;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500623 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
624
625 if (expect_latency > group_slice) {
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100626 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
627 /* scale low_slice according to IO priority
628 * and sync vs async */
629 unsigned low_slice =
630 min(slice, base_low_slice * slice / sync_slice);
631 /* the adapted slice value is scaled to fit all iqs
632 * into the target latency */
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500633 slice = max(slice * group_slice / expect_latency,
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100634 low_slice);
635 }
636 }
Shaohua Lic553f8e2011-01-14 08:41:03 +0100637 return slice;
638}
639
640static inline void
641cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
642{
Vivek Goyalba5bd522011-01-19 08:25:02 -0700643 unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
Shaohua Lic553f8e2011-01-14 08:41:03 +0100644
Vivek Goyaldae739e2009-12-03 12:59:45 -0500645 cfqq->slice_start = jiffies;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100646 cfqq->slice_end = jiffies + slice;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500647 cfqq->allocated_slice = slice;
Jens Axboe7b679132008-05-30 12:23:07 +0200648 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
Jens Axboe44f7c162007-01-19 11:51:58 +1100649}
650
651/*
652 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
653 * isn't valid until the first request from the dispatch is activated
654 * and the slice time set.
655 */
Jens Axboea6151c32009-10-07 20:02:57 +0200656static inline bool cfq_slice_used(struct cfq_queue *cfqq)
Jens Axboe44f7c162007-01-19 11:51:58 +1100657{
658 if (cfq_cfqq_slice_new(cfqq))
Shaohua Lic1e44752010-11-08 15:01:02 +0100659 return false;
Jens Axboe44f7c162007-01-19 11:51:58 +1100660 if (time_before(jiffies, cfqq->slice_end))
Shaohua Lic1e44752010-11-08 15:01:02 +0100661 return false;
Jens Axboe44f7c162007-01-19 11:51:58 +1100662
Shaohua Lic1e44752010-11-08 15:01:02 +0100663 return true;
Jens Axboe44f7c162007-01-19 11:51:58 +1100664}
665
666/*
Jens Axboe5e705372006-07-13 12:39:25 +0200667 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 * We choose the request that is closest to the head right now. Distance
Andreas Mohre8a99052006-03-28 08:59:49 +0200669 * behind the head is penalized and only allowed to a certain extent.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 */
Jens Axboe5e705372006-07-13 12:39:25 +0200671static struct request *
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100672cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673{
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100674 sector_t s1, s2, d1 = 0, d2 = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 unsigned long back_max;
Andreas Mohre8a99052006-03-28 08:59:49 +0200676#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
677#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
678 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679
Jens Axboe5e705372006-07-13 12:39:25 +0200680 if (rq1 == NULL || rq1 == rq2)
681 return rq2;
682 if (rq2 == NULL)
683 return rq1;
Jens Axboe9c2c38a2005-08-24 14:57:54 +0200684
Namhyung Kim229836b2011-05-24 10:23:21 +0200685 if (rq_is_sync(rq1) != rq_is_sync(rq2))
686 return rq_is_sync(rq1) ? rq1 : rq2;
687
Christoph Hellwig65299a32011-08-23 14:50:29 +0200688 if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
689 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
Jens Axboeb53d1ed2011-08-19 08:34:48 +0200690
Tejun Heo83096eb2009-05-07 22:24:39 +0900691 s1 = blk_rq_pos(rq1);
692 s2 = blk_rq_pos(rq2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 /*
695 * by definition, 1KiB is 2 sectors
696 */
697 back_max = cfqd->cfq_back_max * 2;
698
699 /*
700 * Strict one way elevator _except_ in the case where we allow
701 * short backward seeks which are biased as twice the cost of a
702 * similar forward seek.
703 */
704 if (s1 >= last)
705 d1 = s1 - last;
706 else if (s1 + back_max >= last)
707 d1 = (last - s1) * cfqd->cfq_back_penalty;
708 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200709 wrap |= CFQ_RQ1_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710
711 if (s2 >= last)
712 d2 = s2 - last;
713 else if (s2 + back_max >= last)
714 d2 = (last - s2) * cfqd->cfq_back_penalty;
715 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200716 wrap |= CFQ_RQ2_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717
718 /* Found required data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719
Andreas Mohre8a99052006-03-28 08:59:49 +0200720 /*
721 * By doing switch() on the bit mask "wrap" we avoid having to
722 * check two variables for all permutations: --> faster!
723 */
724 switch (wrap) {
Jens Axboe5e705372006-07-13 12:39:25 +0200725 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200726 if (d1 < d2)
Jens Axboe5e705372006-07-13 12:39:25 +0200727 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200728 else if (d2 < d1)
Jens Axboe5e705372006-07-13 12:39:25 +0200729 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200730 else {
731 if (s1 >= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200732 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200733 else
Jens Axboe5e705372006-07-13 12:39:25 +0200734 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200735 }
736
737 case CFQ_RQ2_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200738 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200739 case CFQ_RQ1_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200740 return rq2;
741 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200742 default:
743 /*
744 * Since both rqs are wrapped,
745 * start with the one that's further behind head
746 * (--> only *one* back seek required),
747 * since back seek takes more time than forward.
748 */
749 if (s1 <= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200750 return rq1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 else
Jens Axboe5e705372006-07-13 12:39:25 +0200752 return rq2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 }
754}
755
Jens Axboe498d3aa22007-04-26 12:54:48 +0200756/*
757 * The below is leftmost cache rbtree addon
758 */
Jens Axboe08717142008-01-28 11:38:15 +0100759static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
Jens Axboecc09e292007-04-26 12:53:50 +0200760{
Vivek Goyal615f0252009-12-03 12:59:39 -0500761 /* Service tree is empty */
762 if (!root->count)
763 return NULL;
764
Jens Axboecc09e292007-04-26 12:53:50 +0200765 if (!root->left)
766 root->left = rb_first(&root->rb);
767
Jens Axboe08717142008-01-28 11:38:15 +0100768 if (root->left)
769 return rb_entry(root->left, struct cfq_queue, rb_node);
770
771 return NULL;
Jens Axboecc09e292007-04-26 12:53:50 +0200772}
773
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500774static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
775{
776 if (!root->left)
777 root->left = rb_first(&root->rb);
778
779 if (root->left)
780 return rb_entry_cfqg(root->left);
781
782 return NULL;
783}
784
Jens Axboea36e71f2009-04-15 12:15:11 +0200785static void rb_erase_init(struct rb_node *n, struct rb_root *root)
786{
787 rb_erase(n, root);
788 RB_CLEAR_NODE(n);
789}
790
Jens Axboecc09e292007-04-26 12:53:50 +0200791static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
792{
793 if (root->left == n)
794 root->left = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +0200795 rb_erase_init(n, &root->rb);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +0100796 --root->count;
Jens Axboecc09e292007-04-26 12:53:50 +0200797}
798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799/*
800 * would be nice to take fifo expire time into account as well
801 */
Jens Axboe5e705372006-07-13 12:39:25 +0200802static struct request *
803cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
804 struct request *last)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805{
Jens Axboe21183b02006-07-13 12:33:14 +0200806 struct rb_node *rbnext = rb_next(&last->rb_node);
807 struct rb_node *rbprev = rb_prev(&last->rb_node);
Jens Axboe5e705372006-07-13 12:39:25 +0200808 struct request *next = NULL, *prev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809
Jens Axboe21183b02006-07-13 12:33:14 +0200810 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811
812 if (rbprev)
Jens Axboe5e705372006-07-13 12:39:25 +0200813 prev = rb_entry_rq(rbprev);
Jens Axboe21183b02006-07-13 12:33:14 +0200814
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 if (rbnext)
Jens Axboe5e705372006-07-13 12:39:25 +0200816 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200817 else {
818 rbnext = rb_first(&cfqq->sort_list);
819 if (rbnext && rbnext != &last->rb_node)
Jens Axboe5e705372006-07-13 12:39:25 +0200820 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200821 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100823 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824}
825
Jens Axboed9e76202007-04-20 14:27:50 +0200826static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
827 struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828{
Jens Axboed9e76202007-04-20 14:27:50 +0200829 /*
830 * just an approximation, should be ok.
831 */
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500832 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
Jens Axboe464191c2009-11-30 09:38:13 +0100833 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
Jens Axboed9e76202007-04-20 14:27:50 +0200834}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500836static inline s64
837cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
838{
839 return cfqg->vdisktime - st->min_vdisktime;
840}
841
842static void
843__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
844{
845 struct rb_node **node = &st->rb.rb_node;
846 struct rb_node *parent = NULL;
847 struct cfq_group *__cfqg;
848 s64 key = cfqg_key(st, cfqg);
849 int left = 1;
850
851 while (*node != NULL) {
852 parent = *node;
853 __cfqg = rb_entry_cfqg(parent);
854
855 if (key < cfqg_key(st, __cfqg))
856 node = &parent->rb_left;
857 else {
858 node = &parent->rb_right;
859 left = 0;
860 }
861 }
862
863 if (left)
864 st->left = &cfqg->rb_node;
865
866 rb_link_node(&cfqg->rb_node, parent, node);
867 rb_insert_color(&cfqg->rb_node, &st->rb);
868}
869
870static void
Justin TerAvest8184f932011-03-17 16:12:36 +0100871cfq_update_group_weight(struct cfq_group *cfqg)
872{
873 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
874 if (cfqg->needs_update) {
875 cfqg->weight = cfqg->new_weight;
876 cfqg->needs_update = false;
877 }
878}
879
880static void
881cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
882{
883 BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
884
885 cfq_update_group_weight(cfqg);
886 __cfq_group_service_tree_add(st, cfqg);
887 st->total_weight += cfqg->weight;
888}
889
890static void
891cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500892{
893 struct cfq_rb_root *st = &cfqd->grp_service_tree;
894 struct cfq_group *__cfqg;
895 struct rb_node *n;
896
897 cfqg->nr_cfqq++;
Gui Jianfeng760701b2010-11-30 20:52:47 +0100898 if (!RB_EMPTY_NODE(&cfqg->rb_node))
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500899 return;
900
901 /*
902 * Currently put the group at the end. Later implement something
903 * so that groups get lesser vtime based on their weights, so that
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300904 * if group does not loose all if it was not continuously backlogged.
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500905 */
906 n = rb_last(&st->rb);
907 if (n) {
908 __cfqg = rb_entry_cfqg(n);
909 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
910 } else
911 cfqg->vdisktime = st->min_vdisktime;
Justin TerAvest8184f932011-03-17 16:12:36 +0100912 cfq_group_service_tree_add(st, cfqg);
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500913}
914
915static void
Justin TerAvest8184f932011-03-17 16:12:36 +0100916cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
917{
918 st->total_weight -= cfqg->weight;
919 if (!RB_EMPTY_NODE(&cfqg->rb_node))
920 cfq_rb_erase(&cfqg->rb_node, st);
921}
922
923static void
924cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500925{
926 struct cfq_rb_root *st = &cfqd->grp_service_tree;
927
928 BUG_ON(cfqg->nr_cfqq < 1);
929 cfqg->nr_cfqq--;
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500930
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500931 /* If there are other cfq queues under this group, don't delete it */
932 if (cfqg->nr_cfqq)
933 return;
934
Vivek Goyal2868ef72009-12-03 12:59:48 -0500935 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
Justin TerAvest8184f932011-03-17 16:12:36 +0100936 cfq_group_service_tree_del(st, cfqg);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500937 cfqg->saved_workload_slice = 0;
Vivek Goyale98ef892010-06-18 10:39:47 -0400938 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500939}
940
Justin TerAvest167400d2011-03-12 16:54:00 +0100941static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
942 unsigned int *unaccounted_time)
Vivek Goyaldae739e2009-12-03 12:59:45 -0500943{
Vivek Goyalf75edf22009-12-03 12:59:53 -0500944 unsigned int slice_used;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500945
946 /*
947 * Queue got expired before even a single request completed or
948 * got expired immediately after first request completion.
949 */
950 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
951 /*
952 * Also charge the seek time incurred to the group, otherwise
953 * if there are mutiple queues in the group, each can dispatch
954 * a single request on seeky media and cause lots of seek time
955 * and group will never know it.
956 */
957 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
958 1);
959 } else {
960 slice_used = jiffies - cfqq->slice_start;
Justin TerAvest167400d2011-03-12 16:54:00 +0100961 if (slice_used > cfqq->allocated_slice) {
962 *unaccounted_time = slice_used - cfqq->allocated_slice;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500963 slice_used = cfqq->allocated_slice;
Justin TerAvest167400d2011-03-12 16:54:00 +0100964 }
965 if (time_after(cfqq->slice_start, cfqq->dispatch_start))
966 *unaccounted_time += cfqq->slice_start -
967 cfqq->dispatch_start;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500968 }
969
Vivek Goyaldae739e2009-12-03 12:59:45 -0500970 return slice_used;
971}
972
973static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
Vivek Goyale5ff0822010-04-26 19:25:11 +0200974 struct cfq_queue *cfqq)
Vivek Goyaldae739e2009-12-03 12:59:45 -0500975{
976 struct cfq_rb_root *st = &cfqd->grp_service_tree;
Justin TerAvest167400d2011-03-12 16:54:00 +0100977 unsigned int used_sl, charge, unaccounted_sl = 0;
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500978 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
979 - cfqg->service_tree_idle.count;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500980
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500981 BUG_ON(nr_sync < 0);
Justin TerAvest167400d2011-03-12 16:54:00 +0100982 used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500983
Vivek Goyal02b35082010-08-23 12:23:53 +0200984 if (iops_mode(cfqd))
985 charge = cfqq->slice_dispatch;
986 else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
987 charge = cfqq->allocated_slice;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500988
989 /* Can't update vdisktime while group is on service tree */
Justin TerAvest8184f932011-03-17 16:12:36 +0100990 cfq_group_service_tree_del(st, cfqg);
Vivek Goyal02b35082010-08-23 12:23:53 +0200991 cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
Justin TerAvest8184f932011-03-17 16:12:36 +0100992 /* If a new weight was requested, update now, off tree */
993 cfq_group_service_tree_add(st, cfqg);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500994
995 /* This group is being expired. Save the context */
996 if (time_after(cfqd->workload_expires, jiffies)) {
997 cfqg->saved_workload_slice = cfqd->workload_expires
998 - jiffies;
999 cfqg->saved_workload = cfqd->serving_type;
1000 cfqg->saved_serving_prio = cfqd->serving_prio;
1001 } else
1002 cfqg->saved_workload_slice = 0;
Vivek Goyal2868ef72009-12-03 12:59:48 -05001003
1004 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1005 st->min_vdisktime);
Joe Perchesfd16d262011-06-13 10:42:49 +02001006 cfq_log_cfqq(cfqq->cfqd, cfqq,
1007 "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1008 used_sl, cfqq->slice_dispatch, charge,
1009 iops_mode(cfqd), cfqq->nr_sectors);
Justin TerAvest167400d2011-03-12 16:54:00 +01001010 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
1011 unaccounted_sl);
Vivek Goyale98ef892010-06-18 10:39:47 -04001012 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05001013}
1014
Vivek Goyal25fb5162009-12-03 12:59:46 -05001015#ifdef CONFIG_CFQ_GROUP_IOSCHED
1016static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
1017{
1018 if (blkg)
1019 return container_of(blkg, struct cfq_group, blkg);
1020 return NULL;
1021}
1022
Paul Bolle8aea4542011-06-06 05:07:54 +02001023static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
1024 unsigned int weight)
Vivek Goyalf8d461d2009-12-03 12:59:52 -05001025{
Justin TerAvest8184f932011-03-17 16:12:36 +01001026 struct cfq_group *cfqg = cfqg_of_blkg(blkg);
1027 cfqg->new_weight = weight;
1028 cfqg->needs_update = true;
Vivek Goyalf8d461d2009-12-03 12:59:52 -05001029}
1030
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001031static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
1032 struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
Vivek Goyal25fb5162009-12-03 12:59:46 -05001033{
Vivek Goyal22084192009-12-03 12:59:49 -05001034 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1035 unsigned int major, minor;
Vivek Goyal25fb5162009-12-03 12:59:46 -05001036
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001037 /*
1038 * Add group onto cgroup list. It might happen that bdi->dev is
1039 * not initialized yet. Initialize this new group without major
1040 * and minor info and this info will be filled in once a new thread
1041 * comes for IO.
1042 */
1043 if (bdi->dev) {
Ricky Beniteza74b2ad2010-04-05 18:22:17 +02001044 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001045 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1046 (void *)cfqd, MKDEV(major, minor));
1047 } else
1048 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
1049 (void *)cfqd, 0);
1050
1051 cfqd->nr_blkcg_linked_grps++;
1052 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
1053
1054 /* Add group on cfqd list */
1055 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1056}
1057
1058/*
1059 * Should be called from sleepable context. No request queue lock as per
1060 * cpu stats are allocated dynamically and alloc_percpu needs to be called
1061 * from sleepable context.
1062 */
1063static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
1064{
1065 struct cfq_group *cfqg = NULL;
Vivek Goyal5624a4e2011-05-19 15:38:28 -04001066 int i, j, ret;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001067 struct cfq_rb_root *st;
Vivek Goyal25fb5162009-12-03 12:59:46 -05001068
1069 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
1070 if (!cfqg)
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001071 return NULL;
Vivek Goyal25fb5162009-12-03 12:59:46 -05001072
Vivek Goyal25fb5162009-12-03 12:59:46 -05001073 for_each_cfqg_st(cfqg, i, j, st)
1074 *st = CFQ_RB_ROOT;
1075 RB_CLEAR_NODE(&cfqg->rb_node);
1076
Shaohua Li7700fc42011-07-12 14:24:56 +02001077 cfqg->ttime.last_end_request = jiffies;
1078
Vivek Goyalb1c35762009-12-03 12:59:47 -05001079 /*
1080 * Take the initial reference that will be released on destroy
1081 * This can be thought of a joint reference by cgroup and
1082 * elevator which will be dropped by either elevator exit
1083 * or cgroup deletion path depending on who is exiting first.
1084 */
Shaohua Li329a6782011-01-07 08:48:28 +01001085 cfqg->ref = 1;
Vivek Goyal5624a4e2011-05-19 15:38:28 -04001086
1087 ret = blkio_alloc_blkg_stats(&cfqg->blkg);
1088 if (ret) {
1089 kfree(cfqg);
1090 return NULL;
1091 }
1092
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001093 return cfqg;
1094}
1095
1096static struct cfq_group *
1097cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
1098{
1099 struct cfq_group *cfqg = NULL;
1100 void *key = cfqd;
1101 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
1102 unsigned int major, minor;
Vivek Goyalb1c35762009-12-03 12:59:47 -05001103
Vivek Goyal180be2a2010-09-14 08:47:11 +02001104 /*
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001105 * This is the common case when there are no blkio cgroups.
1106 * Avoid lookup in this case
Vivek Goyal180be2a2010-09-14 08:47:11 +02001107 */
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001108 if (blkcg == &blkio_root_cgroup)
1109 cfqg = &cfqd->root_group;
1110 else
1111 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
1112
1113 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
Vivek Goyal180be2a2010-09-14 08:47:11 +02001114 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001115 cfqg->blkg.dev = MKDEV(major, minor);
1116 }
Vivek Goyal180be2a2010-09-14 08:47:11 +02001117
Vivek Goyal25fb5162009-12-03 12:59:46 -05001118 return cfqg;
1119}
1120
1121/*
Vivek Goyal3e59cf92011-05-19 15:38:21 -04001122 * Search for the cfq group current task belongs to. request_queue lock must
1123 * be held.
Vivek Goyal25fb5162009-12-03 12:59:46 -05001124 */
Vivek Goyal3e59cf92011-05-19 15:38:21 -04001125static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
Vivek Goyal25fb5162009-12-03 12:59:46 -05001126{
Vivek Goyal70087dc2011-05-16 15:24:08 +02001127 struct blkio_cgroup *blkcg;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001128 struct cfq_group *cfqg = NULL, *__cfqg = NULL;
1129 struct request_queue *q = cfqd->queue;
Vivek Goyal25fb5162009-12-03 12:59:46 -05001130
1131 rcu_read_lock();
Vivek Goyal70087dc2011-05-16 15:24:08 +02001132 blkcg = task_blkio_cgroup(current);
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001133 cfqg = cfq_find_cfqg(cfqd, blkcg);
1134 if (cfqg) {
1135 rcu_read_unlock();
1136 return cfqg;
1137 }
1138
1139 /*
1140 * Need to allocate a group. Allocation of group also needs allocation
1141 * of per cpu stats which in-turn takes a mutex() and can block. Hence
1142 * we need to drop rcu lock and queue_lock before we call alloc.
1143 *
1144 * Not taking any queue reference here and assuming that queue is
1145 * around by the time we return. CFQ queue allocation code does
1146 * the same. It might be racy though.
1147 */
1148
1149 rcu_read_unlock();
1150 spin_unlock_irq(q->queue_lock);
1151
1152 cfqg = cfq_alloc_cfqg(cfqd);
1153
1154 spin_lock_irq(q->queue_lock);
1155
1156 rcu_read_lock();
1157 blkcg = task_blkio_cgroup(current);
1158
1159 /*
1160 * If some other thread already allocated the group while we were
1161 * not holding queue lock, free up the group
1162 */
1163 __cfqg = cfq_find_cfqg(cfqd, blkcg);
1164
1165 if (__cfqg) {
1166 kfree(cfqg);
1167 rcu_read_unlock();
1168 return __cfqg;
1169 }
1170
Vivek Goyal3e59cf92011-05-19 15:38:21 -04001171 if (!cfqg)
Vivek Goyal25fb5162009-12-03 12:59:46 -05001172 cfqg = &cfqd->root_group;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001173
1174 cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
Vivek Goyal25fb5162009-12-03 12:59:46 -05001175 rcu_read_unlock();
1176 return cfqg;
1177}
1178
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001179static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1180{
Shaohua Li329a6782011-01-07 08:48:28 +01001181 cfqg->ref++;
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001182 return cfqg;
1183}
1184
Vivek Goyal25fb5162009-12-03 12:59:46 -05001185static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1186{
1187 /* Currently, all async queues are mapped to root group */
1188 if (!cfq_cfqq_sync(cfqq))
1189 cfqg = &cfqq->cfqd->root_group;
1190
1191 cfqq->cfqg = cfqg;
Vivek Goyalb1c35762009-12-03 12:59:47 -05001192 /* cfqq reference on cfqg */
Shaohua Li329a6782011-01-07 08:48:28 +01001193 cfqq->cfqg->ref++;
Vivek Goyal25fb5162009-12-03 12:59:46 -05001194}
Vivek Goyalb1c35762009-12-03 12:59:47 -05001195
1196static void cfq_put_cfqg(struct cfq_group *cfqg)
1197{
1198 struct cfq_rb_root *st;
1199 int i, j;
1200
Shaohua Li329a6782011-01-07 08:48:28 +01001201 BUG_ON(cfqg->ref <= 0);
1202 cfqg->ref--;
1203 if (cfqg->ref)
Vivek Goyalb1c35762009-12-03 12:59:47 -05001204 return;
1205 for_each_cfqg_st(cfqg, i, j, st)
Gui Jianfengb54ce602010-11-30 20:52:46 +01001206 BUG_ON(!RB_EMPTY_ROOT(&st->rb));
Vivek Goyal5624a4e2011-05-19 15:38:28 -04001207 free_percpu(cfqg->blkg.stats_cpu);
Vivek Goyalb1c35762009-12-03 12:59:47 -05001208 kfree(cfqg);
1209}
1210
1211static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1212{
1213 /* Something wrong if we are trying to remove same group twice */
1214 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1215
1216 hlist_del_init(&cfqg->cfqd_node);
1217
Vivek Goyala5395b82011-08-02 09:24:09 +02001218 BUG_ON(cfqd->nr_blkcg_linked_grps <= 0);
1219 cfqd->nr_blkcg_linked_grps--;
1220
Vivek Goyalb1c35762009-12-03 12:59:47 -05001221 /*
1222 * Put the reference taken at the time of creation so that when all
1223 * queues are gone, group can be destroyed.
1224 */
1225 cfq_put_cfqg(cfqg);
1226}
1227
1228static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1229{
1230 struct hlist_node *pos, *n;
1231 struct cfq_group *cfqg;
1232
1233 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1234 /*
1235 * If cgroup removal path got to blk_group first and removed
1236 * it from cgroup list, then it will take care of destroying
1237 * cfqg also.
1238 */
Vivek Goyale98ef892010-06-18 10:39:47 -04001239 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
Vivek Goyalb1c35762009-12-03 12:59:47 -05001240 cfq_destroy_cfqg(cfqd, cfqg);
1241 }
1242}
1243
1244/*
1245 * Blk cgroup controller notification saying that blkio_group object is being
1246 * delinked as associated cgroup object is going away. That also means that
1247 * no new IO will come in this group. So get rid of this group as soon as
1248 * any pending IO in the group is finished.
1249 *
1250 * This function is called under rcu_read_lock(). key is the rcu protected
1251 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1252 * read lock.
1253 *
1254 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1255 * it should not be NULL as even if elevator was exiting, cgroup deltion
1256 * path got to it first.
1257 */
Paul Bolle8aea4542011-06-06 05:07:54 +02001258static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
Vivek Goyalb1c35762009-12-03 12:59:47 -05001259{
1260 unsigned long flags;
1261 struct cfq_data *cfqd = key;
1262
1263 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1264 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1265 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1266}
1267
Vivek Goyal25fb5162009-12-03 12:59:46 -05001268#else /* GROUP_IOSCHED */
Vivek Goyal3e59cf92011-05-19 15:38:21 -04001269static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
Vivek Goyal25fb5162009-12-03 12:59:46 -05001270{
1271 return &cfqd->root_group;
1272}
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001273
1274static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1275{
Dmitry Monakhov50eaeb32010-04-28 19:50:33 +02001276 return cfqg;
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001277}
1278
Vivek Goyal25fb5162009-12-03 12:59:46 -05001279static inline void
1280cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1281 cfqq->cfqg = cfqg;
1282}
1283
Vivek Goyalb1c35762009-12-03 12:59:47 -05001284static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1285static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1286
Vivek Goyal25fb5162009-12-03 12:59:46 -05001287#endif /* GROUP_IOSCHED */
1288
Jens Axboe498d3aa22007-04-26 12:54:48 +02001289/*
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001290 * The cfqd->service_trees holds all pending cfq_queue's that have
Jens Axboe498d3aa22007-04-26 12:54:48 +02001291 * requests waiting to be processed. It is sorted in the order that
1292 * we will service the queues.
1293 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001294static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboea6151c32009-10-07 20:02:57 +02001295 bool add_front)
Jens Axboed9e76202007-04-20 14:27:50 +02001296{
Jens Axboe08717142008-01-28 11:38:15 +01001297 struct rb_node **p, *parent;
1298 struct cfq_queue *__cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +02001299 unsigned long rb_key;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001300 struct cfq_rb_root *service_tree;
Jens Axboe498d3aa22007-04-26 12:54:48 +02001301 int left;
Vivek Goyaldae739e2009-12-03 12:59:45 -05001302 int new_cfqq = 1;
Vivek Goyalae30c282009-12-03 12:59:55 -05001303
Vivek Goyalcdb16e82009-12-03 12:59:38 -05001304 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
Vivek Goyal65b32a52009-12-16 17:52:59 -05001305 cfqq_type(cfqq));
Jens Axboe08717142008-01-28 11:38:15 +01001306 if (cfq_class_idle(cfqq)) {
1307 rb_key = CFQ_IDLE_DELAY;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001308 parent = rb_last(&service_tree->rb);
Jens Axboe08717142008-01-28 11:38:15 +01001309 if (parent && parent != &cfqq->rb_node) {
1310 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1311 rb_key += __cfqq->rb_key;
1312 } else
1313 rb_key += jiffies;
1314 } else if (!add_front) {
Jens Axboeb9c89462009-10-06 20:53:44 +02001315 /*
1316 * Get our rb key offset. Subtract any residual slice
1317 * value carried from last service. A negative resid
1318 * count indicates slice overrun, and this should position
1319 * the next service time further away in the tree.
1320 */
Jens Axboeedd75ff2007-04-19 12:03:34 +02001321 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
Jens Axboeb9c89462009-10-06 20:53:44 +02001322 rb_key -= cfqq->slice_resid;
Jens Axboeedd75ff2007-04-19 12:03:34 +02001323 cfqq->slice_resid = 0;
Corrado Zoccolo48e025e2009-10-05 08:49:23 +02001324 } else {
1325 rb_key = -HZ;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001326 __cfqq = cfq_rb_first(service_tree);
Corrado Zoccolo48e025e2009-10-05 08:49:23 +02001327 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1328 }
Jens Axboed9e76202007-04-20 14:27:50 +02001329
1330 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
Vivek Goyaldae739e2009-12-03 12:59:45 -05001331 new_cfqq = 0;
Jens Axboe99f96282007-02-05 11:56:25 +01001332 /*
Jens Axboed9e76202007-04-20 14:27:50 +02001333 * same position, nothing more to do
Jens Axboe99f96282007-02-05 11:56:25 +01001334 */
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001335 if (rb_key == cfqq->rb_key &&
1336 cfqq->service_tree == service_tree)
Jens Axboed9e76202007-04-20 14:27:50 +02001337 return;
Jens Axboe53b037442006-07-28 09:48:51 +02001338
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001339 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1340 cfqq->service_tree = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02001341 }
Jens Axboed9e76202007-04-20 14:27:50 +02001342
Jens Axboe498d3aa22007-04-26 12:54:48 +02001343 left = 1;
Jens Axboe08717142008-01-28 11:38:15 +01001344 parent = NULL;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001345 cfqq->service_tree = service_tree;
1346 p = &service_tree->rb.rb_node;
Jens Axboed9e76202007-04-20 14:27:50 +02001347 while (*p) {
Jens Axboe67060e32007-04-18 20:13:32 +02001348 struct rb_node **n;
Jens Axboecc09e292007-04-26 12:53:50 +02001349
Jens Axboed9e76202007-04-20 14:27:50 +02001350 parent = *p;
1351 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1352
Jens Axboe0c534e02007-04-18 20:01:57 +02001353 /*
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001354 * sort by key, that represents service time.
Jens Axboe0c534e02007-04-18 20:01:57 +02001355 */
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001356 if (time_before(rb_key, __cfqq->rb_key))
Jens Axboe67060e32007-04-18 20:13:32 +02001357 n = &(*p)->rb_left;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001358 else {
Jens Axboe67060e32007-04-18 20:13:32 +02001359 n = &(*p)->rb_right;
Jens Axboecc09e292007-04-26 12:53:50 +02001360 left = 0;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001361 }
Jens Axboe67060e32007-04-18 20:13:32 +02001362
1363 p = n;
Jens Axboed9e76202007-04-20 14:27:50 +02001364 }
1365
Jens Axboecc09e292007-04-26 12:53:50 +02001366 if (left)
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001367 service_tree->left = &cfqq->rb_node;
Jens Axboecc09e292007-04-26 12:53:50 +02001368
Jens Axboed9e76202007-04-20 14:27:50 +02001369 cfqq->rb_key = rb_key;
1370 rb_link_node(&cfqq->rb_node, parent, p);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001371 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1372 service_tree->count++;
Namhyung Kim20359f22011-05-24 10:23:22 +02001373 if (add_front || !new_cfqq)
Vivek Goyaldae739e2009-12-03 12:59:45 -05001374 return;
Justin TerAvest8184f932011-03-17 16:12:36 +01001375 cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376}
1377
Jens Axboea36e71f2009-04-15 12:15:11 +02001378static struct cfq_queue *
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001379cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1380 sector_t sector, struct rb_node **ret_parent,
1381 struct rb_node ***rb_link)
Jens Axboea36e71f2009-04-15 12:15:11 +02001382{
Jens Axboea36e71f2009-04-15 12:15:11 +02001383 struct rb_node **p, *parent;
1384 struct cfq_queue *cfqq = NULL;
1385
1386 parent = NULL;
1387 p = &root->rb_node;
1388 while (*p) {
1389 struct rb_node **n;
1390
1391 parent = *p;
1392 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1393
1394 /*
1395 * Sort strictly based on sector. Smallest to the left,
1396 * largest to the right.
1397 */
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001398 if (sector > blk_rq_pos(cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001399 n = &(*p)->rb_right;
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001400 else if (sector < blk_rq_pos(cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001401 n = &(*p)->rb_left;
1402 else
1403 break;
1404 p = n;
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001405 cfqq = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +02001406 }
1407
1408 *ret_parent = parent;
1409 if (rb_link)
1410 *rb_link = p;
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001411 return cfqq;
Jens Axboea36e71f2009-04-15 12:15:11 +02001412}
1413
1414static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1415{
Jens Axboea36e71f2009-04-15 12:15:11 +02001416 struct rb_node **p, *parent;
1417 struct cfq_queue *__cfqq;
1418
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001419 if (cfqq->p_root) {
1420 rb_erase(&cfqq->p_node, cfqq->p_root);
1421 cfqq->p_root = NULL;
1422 }
Jens Axboea36e71f2009-04-15 12:15:11 +02001423
1424 if (cfq_class_idle(cfqq))
1425 return;
1426 if (!cfqq->next_rq)
1427 return;
1428
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001429 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001430 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1431 blk_rq_pos(cfqq->next_rq), &parent, &p);
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001432 if (!__cfqq) {
1433 rb_link_node(&cfqq->p_node, parent, p);
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001434 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1435 } else
1436 cfqq->p_root = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +02001437}
1438
Jens Axboe498d3aa22007-04-26 12:54:48 +02001439/*
1440 * Update cfqq's position in the service tree.
1441 */
Jens Axboeedd75ff2007-04-19 12:03:34 +02001442static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001443{
Jens Axboe6d048f52007-04-25 12:44:27 +02001444 /*
1445 * Resorting requires the cfqq to be on the RR list already.
1446 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001447 if (cfq_cfqq_on_rr(cfqq)) {
Jens Axboeedd75ff2007-04-19 12:03:34 +02001448 cfq_service_tree_add(cfqd, cfqq, 0);
Jens Axboea36e71f2009-04-15 12:15:11 +02001449 cfq_prio_tree_add(cfqd, cfqq);
1450 }
Jens Axboe6d048f52007-04-25 12:44:27 +02001451}
1452
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453/*
1454 * add to busy list of queues for service, trying to be fair in ordering
Jens Axboe22e2c502005-06-27 10:55:12 +02001455 * the pending list according to last request service
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456 */
Jens Axboefebffd62008-01-28 13:19:43 +01001457static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458{
Jens Axboe7b679132008-05-30 12:23:07 +02001459 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
Jens Axboe3b181522005-06-27 10:56:24 +02001460 BUG_ON(cfq_cfqq_on_rr(cfqq));
1461 cfq_mark_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 cfqd->busy_queues++;
Shaohua Lief8a41d2011-03-07 09:26:29 +01001463 if (cfq_cfqq_sync(cfqq))
1464 cfqd->busy_sync_queues++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465
Jens Axboeedd75ff2007-04-19 12:03:34 +02001466 cfq_resort_rr_list(cfqd, cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467}
1468
Jens Axboe498d3aa22007-04-26 12:54:48 +02001469/*
1470 * Called when the cfqq no longer has requests pending, remove it from
1471 * the service tree.
1472 */
Jens Axboefebffd62008-01-28 13:19:43 +01001473static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474{
Jens Axboe7b679132008-05-30 12:23:07 +02001475 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
Jens Axboe3b181522005-06-27 10:56:24 +02001476 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1477 cfq_clear_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001479 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1480 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1481 cfqq->service_tree = NULL;
1482 }
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001483 if (cfqq->p_root) {
1484 rb_erase(&cfqq->p_node, cfqq->p_root);
1485 cfqq->p_root = NULL;
1486 }
Jens Axboed9e76202007-04-20 14:27:50 +02001487
Justin TerAvest8184f932011-03-17 16:12:36 +01001488 cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 BUG_ON(!cfqd->busy_queues);
1490 cfqd->busy_queues--;
Shaohua Lief8a41d2011-03-07 09:26:29 +01001491 if (cfq_cfqq_sync(cfqq))
1492 cfqd->busy_sync_queues--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493}
1494
1495/*
1496 * rb tree support functions
1497 */
Jens Axboefebffd62008-01-28 13:19:43 +01001498static void cfq_del_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499{
Jens Axboe5e705372006-07-13 12:39:25 +02001500 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe5e705372006-07-13 12:39:25 +02001501 const int sync = rq_is_sync(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502
Jens Axboeb4878f22005-10-20 16:42:29 +02001503 BUG_ON(!cfqq->queued[sync]);
1504 cfqq->queued[sync]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505
Jens Axboe5e705372006-07-13 12:39:25 +02001506 elv_rb_del(&cfqq->sort_list, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507
Vivek Goyalf04a6422009-12-03 12:59:40 -05001508 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1509 /*
1510 * Queue will be deleted from service tree when we actually
1511 * expire it later. Right now just remove it from prio tree
1512 * as it is empty.
1513 */
1514 if (cfqq->p_root) {
1515 rb_erase(&cfqq->p_node, cfqq->p_root);
1516 cfqq->p_root = NULL;
1517 }
1518 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519}
1520
Jens Axboe5e705372006-07-13 12:39:25 +02001521static void cfq_add_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522{
Jens Axboe5e705372006-07-13 12:39:25 +02001523 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 struct cfq_data *cfqd = cfqq->cfqd;
Jeff Moyer796d5112011-06-02 21:19:05 +02001525 struct request *prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526
Jens Axboe5380a102006-07-13 12:37:56 +02001527 cfqq->queued[rq_is_sync(rq)]++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528
Jeff Moyer796d5112011-06-02 21:19:05 +02001529 elv_rb_add(&cfqq->sort_list, rq);
Jens Axboe5fccbf62006-10-31 14:21:55 +01001530
1531 if (!cfq_cfqq_on_rr(cfqq))
1532 cfq_add_cfqq_rr(cfqd, cfqq);
Jens Axboe5044eed2007-04-25 11:53:48 +02001533
1534 /*
1535 * check if this request is a better next-serve candidate
1536 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001537 prev = cfqq->next_rq;
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001538 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
Jens Axboea36e71f2009-04-15 12:15:11 +02001539
1540 /*
1541 * adjust priority tree position, if ->next_rq changes
1542 */
1543 if (prev != cfqq->next_rq)
1544 cfq_prio_tree_add(cfqd, cfqq);
1545
Jens Axboe5044eed2007-04-25 11:53:48 +02001546 BUG_ON(!cfqq->next_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547}
1548
Jens Axboefebffd62008-01-28 13:19:43 +01001549static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550{
Jens Axboe5380a102006-07-13 12:37:56 +02001551 elv_rb_del(&cfqq->sort_list, rq);
1552 cfqq->queued[rq_is_sync(rq)]--;
Vivek Goyale98ef892010-06-18 10:39:47 -04001553 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1554 rq_data_dir(rq), rq_is_sync(rq));
Jens Axboe5e705372006-07-13 12:39:25 +02001555 cfq_add_rq_rb(rq);
Vivek Goyale98ef892010-06-18 10:39:47 -04001556 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001557 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1558 rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559}
1560
Jens Axboe206dc692006-03-28 13:03:44 +02001561static struct request *
1562cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563{
Jens Axboe206dc692006-03-28 13:03:44 +02001564 struct task_struct *tsk = current;
Tejun Heoc5869802011-12-14 00:33:41 +01001565 struct cfq_io_cq *cic;
Jens Axboe206dc692006-03-28 13:03:44 +02001566 struct cfq_queue *cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567
Jens Axboe4ac845a2008-01-24 08:44:49 +01001568 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001569 if (!cic)
1570 return NULL;
1571
1572 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboe89850f72006-07-22 16:48:31 +02001573 if (cfqq) {
1574 sector_t sector = bio->bi_sector + bio_sectors(bio);
1575
Jens Axboe21183b02006-07-13 12:33:14 +02001576 return elv_rb_find(&cfqq->sort_list, sector);
Jens Axboe89850f72006-07-22 16:48:31 +02001577 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579 return NULL;
1580}
1581
Jens Axboe165125e2007-07-24 09:28:11 +02001582static void cfq_activate_request(struct request_queue *q, struct request *rq)
Jens Axboeb4878f22005-10-20 16:42:29 +02001583{
1584 struct cfq_data *cfqd = q->elevator->elevator_data;
1585
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001586 cfqd->rq_in_driver++;
Jens Axboe7b679132008-05-30 12:23:07 +02001587 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001588 cfqd->rq_in_driver);
Jens Axboe25776e32006-06-01 10:12:26 +02001589
Tejun Heo5b936292009-05-07 22:24:38 +09001590 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02001591}
1592
Jens Axboe165125e2007-07-24 09:28:11 +02001593static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594{
Jens Axboe22e2c502005-06-27 10:55:12 +02001595 struct cfq_data *cfqd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001597 WARN_ON(!cfqd->rq_in_driver);
1598 cfqd->rq_in_driver--;
Jens Axboe7b679132008-05-30 12:23:07 +02001599 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001600 cfqd->rq_in_driver);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601}
1602
Jens Axboeb4878f22005-10-20 16:42:29 +02001603static void cfq_remove_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604{
Jens Axboe5e705372006-07-13 12:39:25 +02001605 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe21183b02006-07-13 12:33:14 +02001606
Jens Axboe5e705372006-07-13 12:39:25 +02001607 if (cfqq->next_rq == rq)
1608 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
Jens Axboeb4878f22005-10-20 16:42:29 +02001610 list_del_init(&rq->queuelist);
Jens Axboe5e705372006-07-13 12:39:25 +02001611 cfq_del_rq_rb(rq);
Jens Axboe374f84a2006-07-23 01:42:19 +02001612
Aaron Carroll45333d52008-08-26 15:52:36 +02001613 cfqq->cfqd->rq_queued--;
Vivek Goyale98ef892010-06-18 10:39:47 -04001614 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1615 rq_data_dir(rq), rq_is_sync(rq));
Christoph Hellwig65299a32011-08-23 14:50:29 +02001616 if (rq->cmd_flags & REQ_PRIO) {
1617 WARN_ON(!cfqq->prio_pending);
1618 cfqq->prio_pending--;
Jens Axboeb53d1ed2011-08-19 08:34:48 +02001619 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620}
1621
Jens Axboe165125e2007-07-24 09:28:11 +02001622static int cfq_merge(struct request_queue *q, struct request **req,
1623 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624{
1625 struct cfq_data *cfqd = q->elevator->elevator_data;
1626 struct request *__rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627
Jens Axboe206dc692006-03-28 13:03:44 +02001628 __rq = cfq_find_rq_fmerge(cfqd, bio);
Jens Axboe22e2c502005-06-27 10:55:12 +02001629 if (__rq && elv_rq_merge_ok(__rq, bio)) {
Jens Axboe98170642006-07-28 09:23:08 +02001630 *req = __rq;
1631 return ELEVATOR_FRONT_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 }
1633
1634 return ELEVATOR_NO_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635}
1636
Jens Axboe165125e2007-07-24 09:28:11 +02001637static void cfq_merged_request(struct request_queue *q, struct request *req,
Jens Axboe21183b02006-07-13 12:33:14 +02001638 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639{
Jens Axboe21183b02006-07-13 12:33:14 +02001640 if (type == ELEVATOR_FRONT_MERGE) {
Jens Axboe5e705372006-07-13 12:39:25 +02001641 struct cfq_queue *cfqq = RQ_CFQQ(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642
Jens Axboe5e705372006-07-13 12:39:25 +02001643 cfq_reposition_rq_rb(cfqq, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645}
1646
Divyesh Shah812d4022010-04-08 21:14:23 -07001647static void cfq_bio_merged(struct request_queue *q, struct request *req,
1648 struct bio *bio)
1649{
Vivek Goyale98ef892010-06-18 10:39:47 -04001650 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1651 bio_data_dir(bio), cfq_bio_sync(bio));
Divyesh Shah812d4022010-04-08 21:14:23 -07001652}
1653
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654static void
Jens Axboe165125e2007-07-24 09:28:11 +02001655cfq_merged_requests(struct request_queue *q, struct request *rq,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656 struct request *next)
1657{
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001658 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Shaohua Li4a0b75c2011-12-16 14:00:22 +01001659 struct cfq_data *cfqd = q->elevator->elevator_data;
1660
Jens Axboe22e2c502005-06-27 10:55:12 +02001661 /*
1662 * reposition in fifo if next is older than rq
1663 */
1664 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
Jens Axboe30996f42009-10-05 11:03:39 +02001665 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
Jens Axboe22e2c502005-06-27 10:55:12 +02001666 list_move(&rq->queuelist, &next->queuelist);
Jens Axboe30996f42009-10-05 11:03:39 +02001667 rq_set_fifo_time(rq, rq_fifo_time(next));
1668 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001669
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001670 if (cfqq->next_rq == next)
1671 cfqq->next_rq = rq;
Jens Axboeb4878f22005-10-20 16:42:29 +02001672 cfq_remove_request(next);
Vivek Goyale98ef892010-06-18 10:39:47 -04001673 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1674 rq_data_dir(next), rq_is_sync(next));
Shaohua Li4a0b75c2011-12-16 14:00:22 +01001675
1676 cfqq = RQ_CFQQ(next);
1677 /*
1678 * all requests of this queue are merged to other queues, delete it
1679 * from the service tree. If it's the active_queue,
1680 * cfq_dispatch_requests() will choose to expire it or do idle
1681 */
1682 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1683 cfqq != cfqd->active_queue)
1684 cfq_del_cfqq_rr(cfqd, cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001685}
1686
Jens Axboe165125e2007-07-24 09:28:11 +02001687static int cfq_allow_merge(struct request_queue *q, struct request *rq,
Jens Axboeda775262006-12-20 11:04:12 +01001688 struct bio *bio)
1689{
1690 struct cfq_data *cfqd = q->elevator->elevator_data;
Tejun Heoc5869802011-12-14 00:33:41 +01001691 struct cfq_io_cq *cic;
Jens Axboeda775262006-12-20 11:04:12 +01001692 struct cfq_queue *cfqq;
Jens Axboeda775262006-12-20 11:04:12 +01001693
1694 /*
Jens Axboeec8acb62007-01-02 18:32:11 +01001695 * Disallow merge of a sync bio into an async request.
Jens Axboeda775262006-12-20 11:04:12 +01001696 */
Vasily Tarasov91fac312007-04-25 12:29:51 +02001697 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
Jens Axboea6151c32009-10-07 20:02:57 +02001698 return false;
Jens Axboeda775262006-12-20 11:04:12 +01001699
1700 /*
Tejun Heof1a4f4d2011-12-14 00:33:39 +01001701 * Lookup the cfqq that this bio will be queued with and allow
Tejun Heo07c2bd32012-02-08 09:19:42 +01001702 * merge only if rq is queued there.
Jens Axboeda775262006-12-20 11:04:12 +01001703 */
Tejun Heo07c2bd32012-02-08 09:19:42 +01001704 cic = cfq_cic_lookup(cfqd, current->io_context);
1705 if (!cic)
1706 return false;
Jens Axboe719d3402006-12-22 09:38:53 +01001707
Vasily Tarasov91fac312007-04-25 12:29:51 +02001708 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboea6151c32009-10-07 20:02:57 +02001709 return cfqq == RQ_CFQQ(rq);
Jens Axboeda775262006-12-20 11:04:12 +01001710}
1711
Divyesh Shah812df482010-04-08 21:15:35 -07001712static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1713{
1714 del_timer(&cfqd->idle_slice_timer);
Vivek Goyale98ef892010-06-18 10:39:47 -04001715 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
Divyesh Shah812df482010-04-08 21:15:35 -07001716}
1717
Jens Axboefebffd62008-01-28 13:19:43 +01001718static void __cfq_set_active_queue(struct cfq_data *cfqd,
1719 struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001720{
1721 if (cfqq) {
Divyesh Shahb1ffe732010-03-25 15:45:03 +01001722 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1723 cfqd->serving_prio, cfqd->serving_type);
Justin TerAvest62a37f62011-03-23 08:25:44 +01001724 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1725 cfqq->slice_start = 0;
1726 cfqq->dispatch_start = jiffies;
1727 cfqq->allocated_slice = 0;
1728 cfqq->slice_end = 0;
1729 cfqq->slice_dispatch = 0;
1730 cfqq->nr_sectors = 0;
1731
1732 cfq_clear_cfqq_wait_request(cfqq);
1733 cfq_clear_cfqq_must_dispatch(cfqq);
1734 cfq_clear_cfqq_must_alloc_slice(cfqq);
1735 cfq_clear_cfqq_fifo_expire(cfqq);
1736 cfq_mark_cfqq_slice_new(cfqq);
1737
1738 cfq_del_timer(cfqd, cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001739 }
1740
1741 cfqd->active_queue = cfqq;
1742}
1743
1744/*
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001745 * current cfqq expired its slice (or was too idle), select new one
1746 */
1747static void
1748__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Vivek Goyale5ff0822010-04-26 19:25:11 +02001749 bool timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001750{
Jens Axboe7b679132008-05-30 12:23:07 +02001751 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1752
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001753 if (cfq_cfqq_wait_request(cfqq))
Divyesh Shah812df482010-04-08 21:15:35 -07001754 cfq_del_timer(cfqd, cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001755
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001756 cfq_clear_cfqq_wait_request(cfqq);
Vivek Goyalf75edf22009-12-03 12:59:53 -05001757 cfq_clear_cfqq_wait_busy(cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001758
1759 /*
Shaohua Liae54abe2010-02-05 13:11:45 +01001760 * If this cfqq is shared between multiple processes, check to
1761 * make sure that those processes are still issuing I/Os within
1762 * the mean seek distance. If not, it may be time to break the
1763 * queues apart again.
1764 */
1765 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1766 cfq_mark_cfqq_split_coop(cfqq);
1767
1768 /*
Jens Axboe6084cdd2007-04-23 08:25:00 +02001769 * store what was left of this slice, if the queue idled/timed out
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001770 */
Shaohua Lic553f8e2011-01-14 08:41:03 +01001771 if (timed_out) {
1772 if (cfq_cfqq_slice_new(cfqq))
Vivek Goyalba5bd522011-01-19 08:25:02 -07001773 cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
Shaohua Lic553f8e2011-01-14 08:41:03 +01001774 else
1775 cfqq->slice_resid = cfqq->slice_end - jiffies;
Jens Axboe7b679132008-05-30 12:23:07 +02001776 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1777 }
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001778
Vivek Goyale5ff0822010-04-26 19:25:11 +02001779 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
Vivek Goyaldae739e2009-12-03 12:59:45 -05001780
Vivek Goyalf04a6422009-12-03 12:59:40 -05001781 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1782 cfq_del_cfqq_rr(cfqd, cfqq);
1783
Jens Axboeedd75ff2007-04-19 12:03:34 +02001784 cfq_resort_rr_list(cfqd, cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001785
1786 if (cfqq == cfqd->active_queue)
1787 cfqd->active_queue = NULL;
1788
1789 if (cfqd->active_cic) {
Tejun Heo11a31222012-02-07 07:51:30 +01001790 put_io_context(cfqd->active_cic->icq.ioc);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001791 cfqd->active_cic = NULL;
1792 }
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001793}
1794
Vivek Goyale5ff0822010-04-26 19:25:11 +02001795static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001796{
1797 struct cfq_queue *cfqq = cfqd->active_queue;
1798
1799 if (cfqq)
Vivek Goyale5ff0822010-04-26 19:25:11 +02001800 __cfq_slice_expired(cfqd, cfqq, timed_out);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001801}
1802
Jens Axboe498d3aa22007-04-26 12:54:48 +02001803/*
1804 * Get next queue for service. Unless we have a queue preemption,
1805 * we'll simply select the first cfqq in the service tree.
1806 */
Jens Axboe6d048f52007-04-25 12:44:27 +02001807static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02001808{
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001809 struct cfq_rb_root *service_tree =
Vivek Goyalcdb16e82009-12-03 12:59:38 -05001810 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
Vivek Goyal65b32a52009-12-16 17:52:59 -05001811 cfqd->serving_type);
Jens Axboeedd75ff2007-04-19 12:03:34 +02001812
Vivek Goyalf04a6422009-12-03 12:59:40 -05001813 if (!cfqd->rq_queued)
1814 return NULL;
1815
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05001816 /* There is nothing to dispatch */
1817 if (!service_tree)
1818 return NULL;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001819 if (RB_EMPTY_ROOT(&service_tree->rb))
1820 return NULL;
1821 return cfq_rb_first(service_tree);
Jens Axboe6d048f52007-04-25 12:44:27 +02001822}
1823
Vivek Goyalf04a6422009-12-03 12:59:40 -05001824static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1825{
Vivek Goyal25fb5162009-12-03 12:59:46 -05001826 struct cfq_group *cfqg;
Vivek Goyalf04a6422009-12-03 12:59:40 -05001827 struct cfq_queue *cfqq;
1828 int i, j;
1829 struct cfq_rb_root *st;
1830
1831 if (!cfqd->rq_queued)
1832 return NULL;
1833
Vivek Goyal25fb5162009-12-03 12:59:46 -05001834 cfqg = cfq_get_next_cfqg(cfqd);
1835 if (!cfqg)
1836 return NULL;
1837
Vivek Goyalf04a6422009-12-03 12:59:40 -05001838 for_each_cfqg_st(cfqg, i, j, st)
1839 if ((cfqq = cfq_rb_first(st)) != NULL)
1840 return cfqq;
1841 return NULL;
1842}
1843
Jens Axboe498d3aa22007-04-26 12:54:48 +02001844/*
1845 * Get and set a new active queue for service.
1846 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001847static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1848 struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001849{
Jens Axboee00ef792009-11-04 08:54:55 +01001850 if (!cfqq)
Jens Axboea36e71f2009-04-15 12:15:11 +02001851 cfqq = cfq_get_next_queue(cfqd);
Jens Axboe6d048f52007-04-25 12:44:27 +02001852
Jens Axboe22e2c502005-06-27 10:55:12 +02001853 __cfq_set_active_queue(cfqd, cfqq);
Jens Axboe3b181522005-06-27 10:56:24 +02001854 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02001855}
1856
Jens Axboed9e76202007-04-20 14:27:50 +02001857static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1858 struct request *rq)
1859{
Tejun Heo83096eb2009-05-07 22:24:39 +09001860 if (blk_rq_pos(rq) >= cfqd->last_position)
1861 return blk_rq_pos(rq) - cfqd->last_position;
Jens Axboed9e76202007-04-20 14:27:50 +02001862 else
Tejun Heo83096eb2009-05-07 22:24:39 +09001863 return cfqd->last_position - blk_rq_pos(rq);
Jens Axboed9e76202007-04-20 14:27:50 +02001864}
1865
Jeff Moyerb2c18e12009-10-23 17:14:49 -04001866static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Shaohua Lie9ce3352010-03-19 08:03:04 +01001867 struct request *rq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001868{
Shaohua Lie9ce3352010-03-19 08:03:04 +01001869 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
Jens Axboe6d048f52007-04-25 12:44:27 +02001870}
1871
Jens Axboea36e71f2009-04-15 12:15:11 +02001872static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1873 struct cfq_queue *cur_cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001874{
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001875 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
Jens Axboea36e71f2009-04-15 12:15:11 +02001876 struct rb_node *parent, *node;
1877 struct cfq_queue *__cfqq;
1878 sector_t sector = cfqd->last_position;
1879
1880 if (RB_EMPTY_ROOT(root))
1881 return NULL;
1882
1883 /*
1884 * First, if we find a request starting at the end of the last
1885 * request, choose it.
1886 */
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001887 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
Jens Axboea36e71f2009-04-15 12:15:11 +02001888 if (__cfqq)
1889 return __cfqq;
1890
1891 /*
1892 * If the exact sector wasn't found, the parent of the NULL leaf
1893 * will contain the closest sector.
1894 */
1895 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
Shaohua Lie9ce3352010-03-19 08:03:04 +01001896 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001897 return __cfqq;
1898
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001899 if (blk_rq_pos(__cfqq->next_rq) < sector)
Jens Axboea36e71f2009-04-15 12:15:11 +02001900 node = rb_next(&__cfqq->p_node);
1901 else
1902 node = rb_prev(&__cfqq->p_node);
1903 if (!node)
1904 return NULL;
1905
1906 __cfqq = rb_entry(node, struct cfq_queue, p_node);
Shaohua Lie9ce3352010-03-19 08:03:04 +01001907 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001908 return __cfqq;
1909
1910 return NULL;
1911}
1912
1913/*
1914 * cfqd - obvious
1915 * cur_cfqq - passed in so that we don't decide that the current queue is
1916 * closely cooperating with itself.
1917 *
1918 * So, basically we're assuming that that cur_cfqq has dispatched at least
1919 * one request, and that cfqd->last_position reflects a position on the disk
1920 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1921 * assumption.
1922 */
1923static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
Jeff Moyerb3b6d042009-10-23 17:14:51 -04001924 struct cfq_queue *cur_cfqq)
Jens Axboea36e71f2009-04-15 12:15:11 +02001925{
1926 struct cfq_queue *cfqq;
1927
Divyesh Shah39c01b22010-03-25 15:45:57 +01001928 if (cfq_class_idle(cur_cfqq))
1929 return NULL;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04001930 if (!cfq_cfqq_sync(cur_cfqq))
1931 return NULL;
1932 if (CFQQ_SEEKY(cur_cfqq))
1933 return NULL;
1934
Jens Axboea36e71f2009-04-15 12:15:11 +02001935 /*
Gui Jianfengb9d8f4c2009-12-08 08:54:17 +01001936 * Don't search priority tree if it's the only queue in the group.
1937 */
1938 if (cur_cfqq->cfqg->nr_cfqq == 1)
1939 return NULL;
1940
1941 /*
Jens Axboed9e76202007-04-20 14:27:50 +02001942 * We should notice if some of the queues are cooperating, eg
1943 * working closely on the same area of the disk. In that case,
1944 * we can group them together and don't waste time idling.
Jens Axboe6d048f52007-04-25 12:44:27 +02001945 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001946 cfqq = cfqq_close(cfqd, cur_cfqq);
1947 if (!cfqq)
1948 return NULL;
1949
Vivek Goyal8682e1f2009-12-03 12:59:50 -05001950 /* If new queue belongs to different cfq_group, don't choose it */
1951 if (cur_cfqq->cfqg != cfqq->cfqg)
1952 return NULL;
1953
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001954 /*
1955 * It only makes sense to merge sync queues.
1956 */
1957 if (!cfq_cfqq_sync(cfqq))
1958 return NULL;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04001959 if (CFQQ_SEEKY(cfqq))
1960 return NULL;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001961
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001962 /*
1963 * Do not merge queues of different priority classes
1964 */
1965 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1966 return NULL;
1967
Jens Axboea36e71f2009-04-15 12:15:11 +02001968 return cfqq;
Jens Axboe6d048f52007-04-25 12:44:27 +02001969}
1970
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001971/*
1972 * Determine whether we should enforce idle window for this queue.
1973 */
1974
1975static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1976{
1977 enum wl_prio_t prio = cfqq_prio(cfqq);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01001978 struct cfq_rb_root *service_tree = cfqq->service_tree;
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001979
Vivek Goyalf04a6422009-12-03 12:59:40 -05001980 BUG_ON(!service_tree);
1981 BUG_ON(!service_tree->count);
1982
Vivek Goyalb6508c12010-08-23 12:23:33 +02001983 if (!cfqd->cfq_slice_idle)
1984 return false;
1985
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001986 /* We never do for idle class queues. */
1987 if (prio == IDLE_WORKLOAD)
1988 return false;
1989
1990 /* We do for queues that were marked with idle window flag. */
Shaohua Li3c764b72009-12-04 13:12:06 +01001991 if (cfq_cfqq_idle_window(cfqq) &&
1992 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001993 return true;
1994
1995 /*
1996 * Otherwise, we do only if they are the last ones
1997 * in their service tree.
1998 */
Shaohua Lif5f2b6c2011-07-12 14:24:55 +02001999 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2000 !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
Shaohua Lic1e44752010-11-08 15:01:02 +01002001 return true;
Divyesh Shahb1ffe732010-03-25 15:45:03 +01002002 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2003 service_tree->count);
Shaohua Lic1e44752010-11-08 15:01:02 +01002004 return false;
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01002005}
2006
Jens Axboe6d048f52007-04-25 12:44:27 +02002007static void cfq_arm_slice_timer(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02002008{
Jens Axboe17926692007-01-19 11:59:30 +11002009 struct cfq_queue *cfqq = cfqd->active_queue;
Tejun Heoc5869802011-12-14 00:33:41 +01002010 struct cfq_io_cq *cic;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002011 unsigned long sl, group_idle = 0;
Jens Axboe7b14e3b2006-02-28 09:35:11 +01002012
Jens Axboea68bbdd2008-09-24 13:03:33 +02002013 /*
Jens Axboef7d7b7a2008-09-25 11:37:50 +02002014 * SSD device without seek penalty, disable idling. But only do so
2015 * for devices that support queuing, otherwise we still have a problem
2016 * with sync vs async workloads.
Jens Axboea68bbdd2008-09-24 13:03:33 +02002017 */
Jens Axboef7d7b7a2008-09-25 11:37:50 +02002018 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
Jens Axboea68bbdd2008-09-24 13:03:33 +02002019 return;
2020
Jens Axboedd67d052006-06-21 09:36:18 +02002021 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
Jens Axboe6d048f52007-04-25 12:44:27 +02002022 WARN_ON(cfq_cfqq_slice_new(cfqq));
Jens Axboe22e2c502005-06-27 10:55:12 +02002023
2024 /*
2025 * idle is disabled, either manually or by past process history
2026 */
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002027 if (!cfq_should_idle(cfqd, cfqq)) {
2028 /* no queue idling. Check for group idling */
2029 if (cfqd->cfq_group_idle)
2030 group_idle = cfqd->cfq_group_idle;
2031 else
2032 return;
2033 }
Jens Axboe6d048f52007-04-25 12:44:27 +02002034
Jens Axboe22e2c502005-06-27 10:55:12 +02002035 /*
Corrado Zoccolo8e550632009-11-26 10:02:58 +01002036 * still active requests from this queue, don't idle
Jens Axboe7b679132008-05-30 12:23:07 +02002037 */
Corrado Zoccolo8e550632009-11-26 10:02:58 +01002038 if (cfqq->dispatched)
Jens Axboe7b679132008-05-30 12:23:07 +02002039 return;
2040
2041 /*
Jens Axboe22e2c502005-06-27 10:55:12 +02002042 * task has exited, don't wait
2043 */
Jens Axboe206dc692006-03-28 13:03:44 +02002044 cic = cfqd->active_cic;
Tejun Heoc5869802011-12-14 00:33:41 +01002045 if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks))
Jens Axboe6d048f52007-04-25 12:44:27 +02002046 return;
2047
Corrado Zoccolo355b6592009-10-08 08:43:32 +02002048 /*
2049 * If our average think time is larger than the remaining time
2050 * slice, then don't idle. This avoids overrunning the allotted
2051 * time slice.
2052 */
Shaohua Li383cd722011-07-12 14:24:35 +02002053 if (sample_valid(cic->ttime.ttime_samples) &&
2054 (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
Joe Perchesfd16d262011-06-13 10:42:49 +02002055 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
Shaohua Li383cd722011-07-12 14:24:35 +02002056 cic->ttime.ttime_mean);
Corrado Zoccolo355b6592009-10-08 08:43:32 +02002057 return;
Divyesh Shahb1ffe732010-03-25 15:45:03 +01002058 }
Corrado Zoccolo355b6592009-10-08 08:43:32 +02002059
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002060 /* There are other queues in the group, don't do group idle */
2061 if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2062 return;
2063
Jens Axboe3b181522005-06-27 10:56:24 +02002064 cfq_mark_cfqq_wait_request(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002065
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002066 if (group_idle)
2067 sl = cfqd->cfq_group_idle;
2068 else
2069 sl = cfqd->cfq_slice_idle;
Jens Axboe206dc692006-03-28 13:03:44 +02002070
Jens Axboe7b14e3b2006-02-28 09:35:11 +01002071 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
Vivek Goyale98ef892010-06-18 10:39:47 -04002072 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002073 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2074 group_idle ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075}
2076
Jens Axboe498d3aa22007-04-26 12:54:48 +02002077/*
2078 * Move request from internal lists to the request queue dispatch list.
2079 */
Jens Axboe165125e2007-07-24 09:28:11 +02002080static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081{
Jens Axboe3ed9a292007-04-23 08:33:33 +02002082 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +02002083 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002084
Jens Axboe7b679132008-05-30 12:23:07 +02002085 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2086
Jeff Moyer06d21882009-09-11 17:08:59 +02002087 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
Jens Axboe5380a102006-07-13 12:37:56 +02002088 cfq_remove_request(rq);
Jens Axboe6d048f52007-04-25 12:44:27 +02002089 cfqq->dispatched++;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002090 (RQ_CFQG(rq))->dispatched++;
Jens Axboe5380a102006-07-13 12:37:56 +02002091 elv_dispatch_sort(q, rq);
Jens Axboe3ed9a292007-04-23 08:33:33 +02002092
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01002093 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
Vivek Goyalc4e78932010-08-23 12:25:03 +02002094 cfqq->nr_sectors += blk_rq_sectors(rq);
Vivek Goyale98ef892010-06-18 10:39:47 -04002095 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
Divyesh Shah84c124d2010-04-09 08:31:19 +02002096 rq_data_dir(rq), rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002097}
2098
2099/*
2100 * return expired entry, or NULL to just start from scratch in rbtree
2101 */
Jens Axboefebffd62008-01-28 13:19:43 +01002102static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103{
Jens Axboe30996f42009-10-05 11:03:39 +02002104 struct request *rq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105
Jens Axboe3b181522005-06-27 10:56:24 +02002106 if (cfq_cfqq_fifo_expire(cfqq))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 return NULL;
Jens Axboecb887412007-01-19 12:01:16 +11002108
2109 cfq_mark_cfqq_fifo_expire(cfqq);
2110
Jens Axboe89850f72006-07-22 16:48:31 +02002111 if (list_empty(&cfqq->fifo))
2112 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
Jens Axboe89850f72006-07-22 16:48:31 +02002114 rq = rq_entry_fifo(cfqq->fifo.next);
Jens Axboe30996f42009-10-05 11:03:39 +02002115 if (time_before(jiffies, rq_fifo_time(rq)))
Jens Axboe7b679132008-05-30 12:23:07 +02002116 rq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117
Jens Axboe30996f42009-10-05 11:03:39 +02002118 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
Jens Axboe6d048f52007-04-25 12:44:27 +02002119 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120}
2121
Jens Axboe22e2c502005-06-27 10:55:12 +02002122static inline int
2123cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2124{
2125 const int base_rq = cfqd->cfq_slice_async_rq;
2126
2127 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2128
Namhyung Kimb9f8ce02011-05-24 10:23:21 +02002129 return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +02002130}
2131
2132/*
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002133 * Must be called with the queue_lock held.
2134 */
2135static int cfqq_process_refs(struct cfq_queue *cfqq)
2136{
2137 int process_refs, io_refs;
2138
2139 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
Shaohua Li30d7b942011-01-07 08:46:59 +01002140 process_refs = cfqq->ref - io_refs;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002141 BUG_ON(process_refs < 0);
2142 return process_refs;
2143}
2144
2145static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2146{
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002147 int process_refs, new_process_refs;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002148 struct cfq_queue *__cfqq;
2149
Jeff Moyerc10b61f2010-06-17 10:19:11 -04002150 /*
2151 * If there are no process references on the new_cfqq, then it is
2152 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2153 * chain may have dropped their last reference (not just their
2154 * last process reference).
2155 */
2156 if (!cfqq_process_refs(new_cfqq))
2157 return;
2158
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002159 /* Avoid a circular list and skip interim queue merges */
2160 while ((__cfqq = new_cfqq->new_cfqq)) {
2161 if (__cfqq == cfqq)
2162 return;
2163 new_cfqq = __cfqq;
2164 }
2165
2166 process_refs = cfqq_process_refs(cfqq);
Jeff Moyerc10b61f2010-06-17 10:19:11 -04002167 new_process_refs = cfqq_process_refs(new_cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002168 /*
2169 * If the process for the cfqq has gone away, there is no
2170 * sense in merging the queues.
2171 */
Jeff Moyerc10b61f2010-06-17 10:19:11 -04002172 if (process_refs == 0 || new_process_refs == 0)
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002173 return;
2174
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002175 /*
2176 * Merge in the direction of the lesser amount of work.
2177 */
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002178 if (new_process_refs >= process_refs) {
2179 cfqq->new_cfqq = new_cfqq;
Shaohua Li30d7b942011-01-07 08:46:59 +01002180 new_cfqq->ref += process_refs;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002181 } else {
2182 new_cfqq->new_cfqq = cfqq;
Shaohua Li30d7b942011-01-07 08:46:59 +01002183 cfqq->ref += new_process_refs;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002184 }
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002185}
2186
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002187static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
Vivek Goyal65b32a52009-12-16 17:52:59 -05002188 struct cfq_group *cfqg, enum wl_prio_t prio)
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002189{
2190 struct cfq_queue *queue;
2191 int i;
2192 bool key_valid = false;
2193 unsigned long lowest_key = 0;
2194 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2195
Vivek Goyal65b32a52009-12-16 17:52:59 -05002196 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2197 /* select the one with lowest rb_key */
2198 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002199 if (queue &&
2200 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2201 lowest_key = queue->rb_key;
2202 cur_best = i;
2203 key_valid = true;
2204 }
2205 }
2206
2207 return cur_best;
2208}
2209
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002210static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002211{
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002212 unsigned slice;
2213 unsigned count;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002214 struct cfq_rb_root *st;
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002215 unsigned group_slice;
Shaohua Li writese4ea0c12010-12-13 14:32:22 +01002216 enum wl_prio_t original_prio = cfqd->serving_prio;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002217
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002218 /* Choose next priority. RT > BE > IDLE */
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002219 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002220 cfqd->serving_prio = RT_WORKLOAD;
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002221 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002222 cfqd->serving_prio = BE_WORKLOAD;
2223 else {
2224 cfqd->serving_prio = IDLE_WORKLOAD;
2225 cfqd->workload_expires = jiffies + 1;
2226 return;
2227 }
2228
Shaohua Li writese4ea0c12010-12-13 14:32:22 +01002229 if (original_prio != cfqd->serving_prio)
2230 goto new_workload;
2231
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002232 /*
2233 * For RT and BE, we have to choose also the type
2234 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2235 * expiration time
2236 */
Vivek Goyal65b32a52009-12-16 17:52:59 -05002237 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002238 count = st->count;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002239
2240 /*
Vivek Goyal65b32a52009-12-16 17:52:59 -05002241 * check workload expiration, and that we still have other queues ready
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002242 */
Vivek Goyal65b32a52009-12-16 17:52:59 -05002243 if (count && !time_after(jiffies, cfqd->workload_expires))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002244 return;
2245
Shaohua Li writese4ea0c12010-12-13 14:32:22 +01002246new_workload:
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002247 /* otherwise select new workload type */
2248 cfqd->serving_type =
Vivek Goyal65b32a52009-12-16 17:52:59 -05002249 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2250 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002251 count = st->count;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002252
2253 /*
2254 * the workload slice is computed as a fraction of target latency
2255 * proportional to the number of queues in that workload, over
2256 * all the queues in the same priority class
2257 */
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002258 group_slice = cfq_group_slice(cfqd, cfqg);
2259
2260 slice = group_slice * count /
2261 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2262 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002263
Vivek Goyalf26bd1f2009-12-03 12:59:54 -05002264 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2265 unsigned int tmp;
2266
2267 /*
2268 * Async queues are currently system wide. Just taking
2269 * proportion of queues with-in same group will lead to higher
2270 * async ratio system wide as generally root group is going
2271 * to have higher weight. A more accurate thing would be to
2272 * calculate system wide asnc/sync ratio.
2273 */
2274 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2275 tmp = tmp/cfqd->busy_queues;
2276 slice = min_t(unsigned, slice, tmp);
2277
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002278 /* async workload slice is scaled down according to
2279 * the sync/async slice ratio. */
2280 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
Vivek Goyalf26bd1f2009-12-03 12:59:54 -05002281 } else
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002282 /* sync workload slice is at least 2 * cfq_slice_idle */
2283 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2284
2285 slice = max_t(unsigned, slice, CFQ_MIN_TT);
Divyesh Shahb1ffe732010-03-25 15:45:03 +01002286 cfq_log(cfqd, "workload slice:%d", slice);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002287 cfqd->workload_expires = jiffies + slice;
2288}
2289
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002290static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2291{
2292 struct cfq_rb_root *st = &cfqd->grp_service_tree;
Vivek Goyal25bc6b02009-12-03 12:59:43 -05002293 struct cfq_group *cfqg;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002294
2295 if (RB_EMPTY_ROOT(&st->rb))
2296 return NULL;
Vivek Goyal25bc6b02009-12-03 12:59:43 -05002297 cfqg = cfq_rb_first_group(st);
Vivek Goyal25bc6b02009-12-03 12:59:43 -05002298 update_min_vdisktime(st);
2299 return cfqg;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002300}
2301
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002302static void cfq_choose_cfqg(struct cfq_data *cfqd)
2303{
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002304 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2305
2306 cfqd->serving_group = cfqg;
Vivek Goyaldae739e2009-12-03 12:59:45 -05002307
2308 /* Restore the workload type data */
2309 if (cfqg->saved_workload_slice) {
2310 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2311 cfqd->serving_type = cfqg->saved_workload;
2312 cfqd->serving_prio = cfqg->saved_serving_prio;
Gui Jianfeng66ae2912009-12-15 10:08:45 +01002313 } else
2314 cfqd->workload_expires = jiffies - 1;
2315
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002316 choose_service_tree(cfqd, cfqg);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002317}
2318
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002319/*
Jens Axboe498d3aa22007-04-26 12:54:48 +02002320 * Select a queue for service. If we have a current active queue,
2321 * check whether to continue servicing it, or retrieve and set a new one.
Jens Axboe22e2c502005-06-27 10:55:12 +02002322 */
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002323static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02002324{
Jens Axboea36e71f2009-04-15 12:15:11 +02002325 struct cfq_queue *cfqq, *new_cfqq = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02002326
2327 cfqq = cfqd->active_queue;
2328 if (!cfqq)
2329 goto new_queue;
2330
Vivek Goyalf04a6422009-12-03 12:59:40 -05002331 if (!cfqd->rq_queued)
2332 return NULL;
Vivek Goyalc244bb52009-12-08 17:52:57 -05002333
2334 /*
2335 * We were waiting for group to get backlogged. Expire the queue
2336 */
2337 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2338 goto expire;
2339
Jens Axboe22e2c502005-06-27 10:55:12 +02002340 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002341 * The active queue has run out of time, expire it and select new.
Jens Axboe22e2c502005-06-27 10:55:12 +02002342 */
Vivek Goyal7667aa02009-12-08 17:52:58 -05002343 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2344 /*
2345 * If slice had not expired at the completion of last request
2346 * we might not have turned on wait_busy flag. Don't expire
2347 * the queue yet. Allow the group to get backlogged.
2348 *
2349 * The very fact that we have used the slice, that means we
2350 * have been idling all along on this queue and it should be
2351 * ok to wait for this request to complete.
2352 */
Vivek Goyal82bbbf22009-12-10 19:25:41 +01002353 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2354 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2355 cfqq = NULL;
Vivek Goyal7667aa02009-12-08 17:52:58 -05002356 goto keep_queue;
Vivek Goyal82bbbf22009-12-10 19:25:41 +01002357 } else
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002358 goto check_group_idle;
Vivek Goyal7667aa02009-12-08 17:52:58 -05002359 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002360
2361 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002362 * The active queue has requests and isn't expired, allow it to
2363 * dispatch.
Jens Axboe22e2c502005-06-27 10:55:12 +02002364 */
Jens Axboedd67d052006-06-21 09:36:18 +02002365 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +02002366 goto keep_queue;
Jens Axboe6d048f52007-04-25 12:44:27 +02002367
2368 /*
Jens Axboea36e71f2009-04-15 12:15:11 +02002369 * If another queue has a request waiting within our mean seek
2370 * distance, let it run. The expire code will check for close
2371 * cooperators and put the close queue at the front of the service
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002372 * tree. If possible, merge the expiring queue with the new cfqq.
Jens Axboea36e71f2009-04-15 12:15:11 +02002373 */
Jeff Moyerb3b6d042009-10-23 17:14:51 -04002374 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002375 if (new_cfqq) {
2376 if (!cfqq->new_cfqq)
2377 cfq_setup_merge(cfqq, new_cfqq);
Jens Axboea36e71f2009-04-15 12:15:11 +02002378 goto expire;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002379 }
Jens Axboea36e71f2009-04-15 12:15:11 +02002380
2381 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002382 * No requests pending. If the active queue still has requests in
2383 * flight or is idling for a new request, allow either of these
2384 * conditions to happen (or time out) before selecting a new queue.
2385 */
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002386 if (timer_pending(&cfqd->idle_slice_timer)) {
2387 cfqq = NULL;
2388 goto keep_queue;
2389 }
2390
Shaohua Li8e1ac662010-11-08 15:01:04 +01002391 /*
2392 * This is a deep seek queue, but the device is much faster than
2393 * the queue can deliver, don't idle
2394 **/
2395 if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2396 (cfq_cfqq_slice_new(cfqq) ||
2397 (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2398 cfq_clear_cfqq_deep(cfqq);
2399 cfq_clear_cfqq_idle_window(cfqq);
2400 }
2401
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02002402 if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2403 cfqq = NULL;
2404 goto keep_queue;
2405 }
2406
2407 /*
2408 * If group idle is enabled and there are requests dispatched from
2409 * this group, wait for requests to complete.
2410 */
2411check_group_idle:
Shaohua Li7700fc42011-07-12 14:24:56 +02002412 if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2413 cfqq->cfqg->dispatched &&
2414 !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
Jens Axboecaaa5f92006-06-16 11:23:00 +02002415 cfqq = NULL;
2416 goto keep_queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02002417 }
2418
Jens Axboe3b181522005-06-27 10:56:24 +02002419expire:
Vivek Goyale5ff0822010-04-26 19:25:11 +02002420 cfq_slice_expired(cfqd, 0);
Jens Axboe3b181522005-06-27 10:56:24 +02002421new_queue:
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002422 /*
2423 * Current queue expired. Check if we have to switch to a new
2424 * service tree
2425 */
2426 if (!new_cfqq)
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002427 cfq_choose_cfqg(cfqd);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002428
Jens Axboea36e71f2009-04-15 12:15:11 +02002429 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002430keep_queue:
Jens Axboe3b181522005-06-27 10:56:24 +02002431 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02002432}
2433
Jens Axboefebffd62008-01-28 13:19:43 +01002434static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
Jens Axboed9e76202007-04-20 14:27:50 +02002435{
2436 int dispatched = 0;
2437
2438 while (cfqq->next_rq) {
2439 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2440 dispatched++;
2441 }
2442
2443 BUG_ON(!list_empty(&cfqq->fifo));
Vivek Goyalf04a6422009-12-03 12:59:40 -05002444
2445 /* By default cfqq is not expired if it is empty. Do it explicitly */
Vivek Goyale5ff0822010-04-26 19:25:11 +02002446 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
Jens Axboed9e76202007-04-20 14:27:50 +02002447 return dispatched;
2448}
2449
Jens Axboe498d3aa22007-04-26 12:54:48 +02002450/*
2451 * Drain our current requests. Used for barriers and when switching
2452 * io schedulers on-the-fly.
2453 */
Jens Axboed9e76202007-04-20 14:27:50 +02002454static int cfq_forced_dispatch(struct cfq_data *cfqd)
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002455{
Jens Axboe08717142008-01-28 11:38:15 +01002456 struct cfq_queue *cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +02002457 int dispatched = 0;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002458
Divyesh Shah3440c492010-04-09 09:29:57 +02002459 /* Expire the timeslice of the current active queue first */
Vivek Goyale5ff0822010-04-26 19:25:11 +02002460 cfq_slice_expired(cfqd, 0);
Divyesh Shah3440c492010-04-09 09:29:57 +02002461 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2462 __cfq_set_active_queue(cfqd, cfqq);
Vivek Goyalf04a6422009-12-03 12:59:40 -05002463 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
Divyesh Shah3440c492010-04-09 09:29:57 +02002464 }
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002465
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002466 BUG_ON(cfqd->busy_queues);
2467
Jeff Moyer69237152009-06-12 15:29:30 +02002468 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002469 return dispatched;
2470}
2471
Shaohua Liabc3c742010-03-01 09:20:54 +01002472static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2473 struct cfq_queue *cfqq)
2474{
2475 /* the queue hasn't finished any request, can't estimate */
2476 if (cfq_cfqq_slice_new(cfqq))
Shaohua Lic1e44752010-11-08 15:01:02 +01002477 return true;
Shaohua Liabc3c742010-03-01 09:20:54 +01002478 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2479 cfqq->slice_end))
Shaohua Lic1e44752010-11-08 15:01:02 +01002480 return true;
Shaohua Liabc3c742010-03-01 09:20:54 +01002481
Shaohua Lic1e44752010-11-08 15:01:02 +01002482 return false;
Shaohua Liabc3c742010-03-01 09:20:54 +01002483}
2484
Jens Axboe0b182d62009-10-06 20:49:37 +02002485static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe2f5cb732009-04-07 08:51:19 +02002486{
Jens Axboe2f5cb732009-04-07 08:51:19 +02002487 unsigned int max_dispatch;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002488
Jens Axboe2f5cb732009-04-07 08:51:19 +02002489 /*
Jens Axboe5ad531d2009-07-03 12:57:48 +02002490 * Drain async requests before we start sync IO
2491 */
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01002492 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
Jens Axboe0b182d62009-10-06 20:49:37 +02002493 return false;
Jens Axboe5ad531d2009-07-03 12:57:48 +02002494
2495 /*
Jens Axboe2f5cb732009-04-07 08:51:19 +02002496 * If this is an async queue and we have sync IO in flight, let it wait
2497 */
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01002498 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
Jens Axboe0b182d62009-10-06 20:49:37 +02002499 return false;
Jens Axboe2f5cb732009-04-07 08:51:19 +02002500
Shaohua Liabc3c742010-03-01 09:20:54 +01002501 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002502 if (cfq_class_idle(cfqq))
2503 max_dispatch = 1;
2504
2505 /*
2506 * Does this cfqq already have too much IO in flight?
2507 */
2508 if (cfqq->dispatched >= max_dispatch) {
Shaohua Lief8a41d2011-03-07 09:26:29 +01002509 bool promote_sync = false;
Jens Axboe2f5cb732009-04-07 08:51:19 +02002510 /*
2511 * idle queue must always only have a single IO in flight
2512 */
Jens Axboe3ed9a292007-04-23 08:33:33 +02002513 if (cfq_class_idle(cfqq))
Jens Axboe0b182d62009-10-06 20:49:37 +02002514 return false;
Jens Axboe3ed9a292007-04-23 08:33:33 +02002515
Jens Axboe2f5cb732009-04-07 08:51:19 +02002516 /*
Li, Shaohuac4ade942011-03-23 08:30:34 +01002517 * If there is only one sync queue
2518 * we can ignore async queue here and give the sync
Shaohua Lief8a41d2011-03-07 09:26:29 +01002519 * queue no dispatch limit. The reason is a sync queue can
2520 * preempt async queue, limiting the sync queue doesn't make
2521 * sense. This is useful for aiostress test.
2522 */
Li, Shaohuac4ade942011-03-23 08:30:34 +01002523 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2524 promote_sync = true;
Shaohua Lief8a41d2011-03-07 09:26:29 +01002525
2526 /*
Jens Axboe2f5cb732009-04-07 08:51:19 +02002527 * We have other queues, don't allow more IO from this one
2528 */
Shaohua Lief8a41d2011-03-07 09:26:29 +01002529 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2530 !promote_sync)
Jens Axboe0b182d62009-10-06 20:49:37 +02002531 return false;
Jens Axboe9ede2092007-01-19 12:11:44 +11002532
Jens Axboe2f5cb732009-04-07 08:51:19 +02002533 /*
Shaohua Li474b18c2009-12-03 12:58:05 +01002534 * Sole queue user, no limit
Vivek Goyal365722b2009-10-03 15:21:27 +02002535 */
Shaohua Lief8a41d2011-03-07 09:26:29 +01002536 if (cfqd->busy_queues == 1 || promote_sync)
Shaohua Liabc3c742010-03-01 09:20:54 +01002537 max_dispatch = -1;
2538 else
2539 /*
2540 * Normally we start throttling cfqq when cfq_quantum/2
2541 * requests have been dispatched. But we can drive
2542 * deeper queue depths at the beginning of slice
2543 * subjected to upper limit of cfq_quantum.
2544 * */
2545 max_dispatch = cfqd->cfq_quantum;
Jens Axboe8e296752009-10-03 16:26:03 +02002546 }
2547
2548 /*
2549 * Async queues must wait a bit before being allowed dispatch.
2550 * We also ramp up the dispatch depth gradually for async IO,
2551 * based on the last sync IO we serviced
2552 */
Jens Axboe963b72f2009-10-03 19:42:18 +02002553 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
Corrado Zoccolo573412b2009-12-06 11:48:52 +01002554 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
Jens Axboe8e296752009-10-03 16:26:03 +02002555 unsigned int depth;
Vivek Goyal365722b2009-10-03 15:21:27 +02002556
Jens Axboe61f0c1d2009-10-03 19:46:03 +02002557 depth = last_sync / cfqd->cfq_slice[1];
Jens Axboee00c54c2009-10-04 20:36:19 +02002558 if (!depth && !cfqq->dispatched)
2559 depth = 1;
Jens Axboe8e296752009-10-03 16:26:03 +02002560 if (depth < max_dispatch)
2561 max_dispatch = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562 }
2563
Jens Axboe0b182d62009-10-06 20:49:37 +02002564 /*
2565 * If we're below the current max, allow a dispatch
2566 */
2567 return cfqq->dispatched < max_dispatch;
2568}
2569
2570/*
2571 * Dispatch a request from cfqq, moving them to the request queue
2572 * dispatch list.
2573 */
2574static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2575{
2576 struct request *rq;
2577
2578 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2579
2580 if (!cfq_may_dispatch(cfqd, cfqq))
2581 return false;
2582
2583 /*
2584 * follow expired path, else get first next available
2585 */
2586 rq = cfq_check_fifo(cfqq);
2587 if (!rq)
2588 rq = cfqq->next_rq;
2589
2590 /*
2591 * insert request into driver dispatch list
2592 */
2593 cfq_dispatch_insert(cfqd->queue, rq);
2594
2595 if (!cfqd->active_cic) {
Tejun Heoc5869802011-12-14 00:33:41 +01002596 struct cfq_io_cq *cic = RQ_CIC(rq);
Jens Axboe0b182d62009-10-06 20:49:37 +02002597
Tejun Heoc5869802011-12-14 00:33:41 +01002598 atomic_long_inc(&cic->icq.ioc->refcount);
Jens Axboe0b182d62009-10-06 20:49:37 +02002599 cfqd->active_cic = cic;
2600 }
2601
2602 return true;
2603}
2604
2605/*
2606 * Find the cfqq that we need to service and move a request from that to the
2607 * dispatch list
2608 */
2609static int cfq_dispatch_requests(struct request_queue *q, int force)
2610{
2611 struct cfq_data *cfqd = q->elevator->elevator_data;
2612 struct cfq_queue *cfqq;
2613
2614 if (!cfqd->busy_queues)
2615 return 0;
2616
2617 if (unlikely(force))
2618 return cfq_forced_dispatch(cfqd);
2619
2620 cfqq = cfq_select_queue(cfqd);
2621 if (!cfqq)
Jens Axboe8e296752009-10-03 16:26:03 +02002622 return 0;
2623
Jens Axboe2f5cb732009-04-07 08:51:19 +02002624 /*
Jens Axboe0b182d62009-10-06 20:49:37 +02002625 * Dispatch a request from this cfqq, if it is allowed
Jens Axboe2f5cb732009-04-07 08:51:19 +02002626 */
Jens Axboe0b182d62009-10-06 20:49:37 +02002627 if (!cfq_dispatch_request(cfqd, cfqq))
2628 return 0;
2629
Jens Axboe2f5cb732009-04-07 08:51:19 +02002630 cfqq->slice_dispatch++;
Jens Axboeb0291952009-04-07 11:38:31 +02002631 cfq_clear_cfqq_must_dispatch(cfqq);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002632
2633 /*
2634 * expire an async queue immediately if it has used up its slice. idle
2635 * queue always expire after 1 dispatch round.
2636 */
2637 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2638 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2639 cfq_class_idle(cfqq))) {
2640 cfqq->slice_end = jiffies + 1;
Vivek Goyale5ff0822010-04-26 19:25:11 +02002641 cfq_slice_expired(cfqd, 0);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002642 }
2643
Shan Weib217a902009-09-01 10:06:42 +02002644 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
Jens Axboe2f5cb732009-04-07 08:51:19 +02002645 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002646}
2647
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648/*
Jens Axboe5e705372006-07-13 12:39:25 +02002649 * task holds one reference to the queue, dropped when task exits. each rq
2650 * in-flight on this queue also holds a reference, dropped when rq is freed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002651 *
Vivek Goyalb1c35762009-12-03 12:59:47 -05002652 * Each cfq queue took a reference on the parent group. Drop it now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002653 * queue lock must be held here.
2654 */
2655static void cfq_put_queue(struct cfq_queue *cfqq)
2656{
Jens Axboe22e2c502005-06-27 10:55:12 +02002657 struct cfq_data *cfqd = cfqq->cfqd;
Justin TerAvest0bbfeb82011-03-01 15:05:08 -05002658 struct cfq_group *cfqg;
Jens Axboe22e2c502005-06-27 10:55:12 +02002659
Shaohua Li30d7b942011-01-07 08:46:59 +01002660 BUG_ON(cfqq->ref <= 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661
Shaohua Li30d7b942011-01-07 08:46:59 +01002662 cfqq->ref--;
2663 if (cfqq->ref)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002664 return;
2665
Jens Axboe7b679132008-05-30 12:23:07 +02002666 cfq_log_cfqq(cfqd, cfqq, "put_queue");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002667 BUG_ON(rb_first(&cfqq->sort_list));
Jens Axboe22e2c502005-06-27 10:55:12 +02002668 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
Vivek Goyalb1c35762009-12-03 12:59:47 -05002669 cfqg = cfqq->cfqg;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002670
Jens Axboe28f95cbc2007-01-19 12:09:53 +11002671 if (unlikely(cfqd->active_queue == cfqq)) {
Vivek Goyale5ff0822010-04-26 19:25:11 +02002672 __cfq_slice_expired(cfqd, cfqq, 0);
Jens Axboe23e018a2009-10-05 08:52:35 +02002673 cfq_schedule_dispatch(cfqd);
Jens Axboe28f95cbc2007-01-19 12:09:53 +11002674 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002675
Vivek Goyalf04a6422009-12-03 12:59:40 -05002676 BUG_ON(cfq_cfqq_on_rr(cfqq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677 kmem_cache_free(cfq_pool, cfqq);
Vivek Goyalb1c35762009-12-03 12:59:47 -05002678 cfq_put_cfqg(cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002679}
2680
Shaohua Lid02a2c02010-05-25 10:16:53 +02002681static void cfq_put_cooperator(struct cfq_queue *cfqq)
Jens Axboe89850f72006-07-22 16:48:31 +02002682{
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002683 struct cfq_queue *__cfqq, *next;
2684
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002685 /*
2686 * If this queue was scheduled to merge with another queue, be
2687 * sure to drop the reference taken on that queue (and others in
2688 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2689 */
2690 __cfqq = cfqq->new_cfqq;
2691 while (__cfqq) {
2692 if (__cfqq == cfqq) {
2693 WARN(1, "cfqq->new_cfqq loop detected\n");
2694 break;
2695 }
2696 next = __cfqq->new_cfqq;
2697 cfq_put_queue(__cfqq);
2698 __cfqq = next;
2699 }
Shaohua Lid02a2c02010-05-25 10:16:53 +02002700}
2701
2702static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2703{
2704 if (unlikely(cfqq == cfqd->active_queue)) {
2705 __cfq_slice_expired(cfqd, cfqq, 0);
2706 cfq_schedule_dispatch(cfqd);
2707 }
2708
2709 cfq_put_cooperator(cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002710
Jens Axboe89850f72006-07-22 16:48:31 +02002711 cfq_put_queue(cfqq);
2712}
2713
Tejun Heo9b84cac2011-12-14 00:33:42 +01002714static void cfq_init_icq(struct io_cq *icq)
2715{
2716 struct cfq_io_cq *cic = icq_to_cic(icq);
2717
2718 cic->ttime.last_end_request = jiffies;
2719}
2720
Tejun Heoc5869802011-12-14 00:33:41 +01002721static void cfq_exit_icq(struct io_cq *icq)
Jens Axboe89850f72006-07-22 16:48:31 +02002722{
Tejun Heoc5869802011-12-14 00:33:41 +01002723 struct cfq_io_cq *cic = icq_to_cic(icq);
Tejun Heo283287a2011-12-14 00:33:38 +01002724 struct cfq_data *cfqd = cic_to_cfqd(cic);
Fabio Checconi4faa3c82008-04-10 08:28:01 +02002725
Jens Axboeff6657c2009-04-08 10:58:57 +02002726 if (cic->cfqq[BLK_RW_ASYNC]) {
2727 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2728 cic->cfqq[BLK_RW_ASYNC] = NULL;
Jens Axboe89850f72006-07-22 16:48:31 +02002729 }
2730
Jens Axboeff6657c2009-04-08 10:58:57 +02002731 if (cic->cfqq[BLK_RW_SYNC]) {
2732 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2733 cic->cfqq[BLK_RW_SYNC] = NULL;
Jens Axboe89850f72006-07-22 16:48:31 +02002734 }
Jens Axboe89850f72006-07-22 16:48:31 +02002735}
2736
Jens Axboefd0928d2008-01-24 08:52:45 +01002737static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
Jens Axboe22e2c502005-06-27 10:55:12 +02002738{
2739 struct task_struct *tsk = current;
2740 int ioprio_class;
2741
Jens Axboe3b181522005-06-27 10:56:24 +02002742 if (!cfq_cfqq_prio_changed(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02002743 return;
2744
Jens Axboefd0928d2008-01-24 08:52:45 +01002745 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +02002746 switch (ioprio_class) {
Jens Axboefe094d92008-01-31 13:08:54 +01002747 default:
2748 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2749 case IOPRIO_CLASS_NONE:
2750 /*
Jens Axboe6d63c272008-05-07 09:51:23 +02002751 * no prio set, inherit CPU scheduling settings
Jens Axboefe094d92008-01-31 13:08:54 +01002752 */
2753 cfqq->ioprio = task_nice_ioprio(tsk);
Jens Axboe6d63c272008-05-07 09:51:23 +02002754 cfqq->ioprio_class = task_nice_ioclass(tsk);
Jens Axboefe094d92008-01-31 13:08:54 +01002755 break;
2756 case IOPRIO_CLASS_RT:
2757 cfqq->ioprio = task_ioprio(ioc);
2758 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2759 break;
2760 case IOPRIO_CLASS_BE:
2761 cfqq->ioprio = task_ioprio(ioc);
2762 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2763 break;
2764 case IOPRIO_CLASS_IDLE:
2765 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2766 cfqq->ioprio = 7;
2767 cfq_clear_cfqq_idle_window(cfqq);
2768 break;
Jens Axboe22e2c502005-06-27 10:55:12 +02002769 }
2770
2771 /*
2772 * keep track of original prio settings in case we have to temporarily
2773 * elevate the priority of this queue
2774 */
2775 cfqq->org_ioprio = cfqq->ioprio;
Jens Axboe3b181522005-06-27 10:56:24 +02002776 cfq_clear_cfqq_prio_changed(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002777}
2778
Tejun Heoc5869802011-12-14 00:33:41 +01002779static void changed_ioprio(struct cfq_io_cq *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02002780{
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002781 struct cfq_data *cfqd = cic_to_cfqd(cic);
Al Viro478a82b2006-03-18 13:25:24 -05002782 struct cfq_queue *cfqq;
Jens Axboe35e60772006-06-14 09:10:45 +02002783
Jens Axboecaaa5f92006-06-16 11:23:00 +02002784 if (unlikely(!cfqd))
2785 return;
2786
Jens Axboeff6657c2009-04-08 10:58:57 +02002787 cfqq = cic->cfqq[BLK_RW_ASYNC];
Jens Axboecaaa5f92006-06-16 11:23:00 +02002788 if (cfqq) {
2789 struct cfq_queue *new_cfqq;
Tejun Heoc5869802011-12-14 00:33:41 +01002790 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc,
Jens Axboeff6657c2009-04-08 10:58:57 +02002791 GFP_ATOMIC);
Jens Axboecaaa5f92006-06-16 11:23:00 +02002792 if (new_cfqq) {
Jens Axboeff6657c2009-04-08 10:58:57 +02002793 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
Jens Axboecaaa5f92006-06-16 11:23:00 +02002794 cfq_put_queue(cfqq);
2795 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002796 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02002797
Jens Axboeff6657c2009-04-08 10:58:57 +02002798 cfqq = cic->cfqq[BLK_RW_SYNC];
Jens Axboecaaa5f92006-06-16 11:23:00 +02002799 if (cfqq)
2800 cfq_mark_cfqq_prio_changed(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002801}
2802
Jens Axboed5036d72009-06-26 10:44:34 +02002803static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboea6151c32009-10-07 20:02:57 +02002804 pid_t pid, bool is_sync)
Jens Axboed5036d72009-06-26 10:44:34 +02002805{
2806 RB_CLEAR_NODE(&cfqq->rb_node);
2807 RB_CLEAR_NODE(&cfqq->p_node);
2808 INIT_LIST_HEAD(&cfqq->fifo);
2809
Shaohua Li30d7b942011-01-07 08:46:59 +01002810 cfqq->ref = 0;
Jens Axboed5036d72009-06-26 10:44:34 +02002811 cfqq->cfqd = cfqd;
2812
2813 cfq_mark_cfqq_prio_changed(cfqq);
2814
2815 if (is_sync) {
2816 if (!cfq_class_idle(cfqq))
2817 cfq_mark_cfqq_idle_window(cfqq);
2818 cfq_mark_cfqq_sync(cfqq);
2819 }
2820 cfqq->pid = pid;
2821}
2822
Vivek Goyal246103332009-12-03 12:59:51 -05002823#ifdef CONFIG_CFQ_GROUP_IOSCHED
Tejun Heoc5869802011-12-14 00:33:41 +01002824static void changed_cgroup(struct cfq_io_cq *cic)
Vivek Goyal246103332009-12-03 12:59:51 -05002825{
2826 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002827 struct cfq_data *cfqd = cic_to_cfqd(cic);
Vivek Goyal246103332009-12-03 12:59:51 -05002828 struct request_queue *q;
2829
2830 if (unlikely(!cfqd))
2831 return;
2832
2833 q = cfqd->queue;
2834
Vivek Goyal246103332009-12-03 12:59:51 -05002835 if (sync_cfqq) {
2836 /*
2837 * Drop reference to sync queue. A new sync queue will be
2838 * assigned in new group upon arrival of a fresh request.
2839 */
2840 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2841 cic_set_cfqq(cic, NULL, 1);
2842 cfq_put_queue(sync_cfqq);
2843 }
Vivek Goyal246103332009-12-03 12:59:51 -05002844}
Vivek Goyal246103332009-12-03 12:59:51 -05002845#endif /* CONFIG_CFQ_GROUP_IOSCHED */
2846
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847static struct cfq_queue *
Jens Axboea6151c32009-10-07 20:02:57 +02002848cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
Jens Axboefd0928d2008-01-24 08:52:45 +01002849 struct io_context *ioc, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002850{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002851 struct cfq_queue *cfqq, *new_cfqq = NULL;
Tejun Heoc5869802011-12-14 00:33:41 +01002852 struct cfq_io_cq *cic;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002853 struct cfq_group *cfqg;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002854
2855retry:
Vivek Goyal3e59cf92011-05-19 15:38:21 -04002856 cfqg = cfq_get_cfqg(cfqd);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002857 cic = cfq_cic_lookup(cfqd, ioc);
Vasily Tarasov91fac312007-04-25 12:29:51 +02002858 /* cic always exists here */
2859 cfqq = cic_to_cfqq(cic, is_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860
Jens Axboe6118b702009-06-30 09:34:12 +02002861 /*
2862 * Always try a new alloc if we fell back to the OOM cfqq
2863 * originally, since it should just be a temporary situation.
2864 */
2865 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2866 cfqq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867 if (new_cfqq) {
2868 cfqq = new_cfqq;
2869 new_cfqq = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02002870 } else if (gfp_mask & __GFP_WAIT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871 spin_unlock_irq(cfqd->queue->queue_lock);
Christoph Lameter94f60302007-07-17 04:03:29 -07002872 new_cfqq = kmem_cache_alloc_node(cfq_pool,
Jens Axboe6118b702009-06-30 09:34:12 +02002873 gfp_mask | __GFP_ZERO,
Christoph Lameter94f60302007-07-17 04:03:29 -07002874 cfqd->queue->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875 spin_lock_irq(cfqd->queue->queue_lock);
Jens Axboe6118b702009-06-30 09:34:12 +02002876 if (new_cfqq)
2877 goto retry;
Jens Axboe22e2c502005-06-27 10:55:12 +02002878 } else {
Christoph Lameter94f60302007-07-17 04:03:29 -07002879 cfqq = kmem_cache_alloc_node(cfq_pool,
2880 gfp_mask | __GFP_ZERO,
2881 cfqd->queue->node);
Kiyoshi Ueda db3b5842005-06-17 16:15:10 +02002882 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002883
Jens Axboe6118b702009-06-30 09:34:12 +02002884 if (cfqq) {
2885 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2886 cfq_init_prio_data(cfqq, ioc);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002887 cfq_link_cfqq_cfqg(cfqq, cfqg);
Jens Axboe6118b702009-06-30 09:34:12 +02002888 cfq_log_cfqq(cfqd, cfqq, "alloced");
2889 } else
2890 cfqq = &cfqd->oom_cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002891 }
2892
2893 if (new_cfqq)
2894 kmem_cache_free(cfq_pool, new_cfqq);
2895
Linus Torvalds1da177e2005-04-16 15:20:36 -07002896 return cfqq;
2897}
2898
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002899static struct cfq_queue **
2900cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2901{
Jens Axboefe094d92008-01-31 13:08:54 +01002902 switch (ioprio_class) {
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002903 case IOPRIO_CLASS_RT:
2904 return &cfqd->async_cfqq[0][ioprio];
2905 case IOPRIO_CLASS_BE:
2906 return &cfqd->async_cfqq[1][ioprio];
2907 case IOPRIO_CLASS_IDLE:
2908 return &cfqd->async_idle_cfqq;
2909 default:
2910 BUG();
2911 }
2912}
2913
Jens Axboe15c31be2007-07-10 13:43:25 +02002914static struct cfq_queue *
Jens Axboea6151c32009-10-07 20:02:57 +02002915cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
Jens Axboe15c31be2007-07-10 13:43:25 +02002916 gfp_t gfp_mask)
2917{
Jens Axboefd0928d2008-01-24 08:52:45 +01002918 const int ioprio = task_ioprio(ioc);
2919 const int ioprio_class = task_ioprio_class(ioc);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002920 struct cfq_queue **async_cfqq = NULL;
Jens Axboe15c31be2007-07-10 13:43:25 +02002921 struct cfq_queue *cfqq = NULL;
2922
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002923 if (!is_sync) {
2924 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2925 cfqq = *async_cfqq;
2926 }
2927
Jens Axboe6118b702009-06-30 09:34:12 +02002928 if (!cfqq)
Jens Axboefd0928d2008-01-24 08:52:45 +01002929 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
Jens Axboe15c31be2007-07-10 13:43:25 +02002930
2931 /*
2932 * pin the queue now that it's allocated, scheduler exit will prune it
2933 */
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002934 if (!is_sync && !(*async_cfqq)) {
Shaohua Li30d7b942011-01-07 08:46:59 +01002935 cfqq->ref++;
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002936 *async_cfqq = cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +02002937 }
2938
Shaohua Li30d7b942011-01-07 08:46:59 +01002939 cfqq->ref++;
Jens Axboe15c31be2007-07-10 13:43:25 +02002940 return cfqq;
2941}
2942
Jens Axboe22e2c502005-06-27 10:55:12 +02002943static void
Shaohua Li383cd722011-07-12 14:24:35 +02002944__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
Jens Axboe22e2c502005-06-27 10:55:12 +02002945{
Shaohua Li383cd722011-07-12 14:24:35 +02002946 unsigned long elapsed = jiffies - ttime->last_end_request;
2947 elapsed = min(elapsed, 2UL * slice_idle);
Jens Axboe22e2c502005-06-27 10:55:12 +02002948
Shaohua Li383cd722011-07-12 14:24:35 +02002949 ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
2950 ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
2951 ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
2952}
2953
2954static void
2955cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Tejun Heoc5869802011-12-14 00:33:41 +01002956 struct cfq_io_cq *cic)
Shaohua Li383cd722011-07-12 14:24:35 +02002957{
Shaohua Lif5f2b6c2011-07-12 14:24:55 +02002958 if (cfq_cfqq_sync(cfqq)) {
Shaohua Li383cd722011-07-12 14:24:35 +02002959 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
Shaohua Lif5f2b6c2011-07-12 14:24:55 +02002960 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
2961 cfqd->cfq_slice_idle);
2962 }
Shaohua Li7700fc42011-07-12 14:24:56 +02002963#ifdef CONFIG_CFQ_GROUP_IOSCHED
2964 __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
2965#endif
Jens Axboe22e2c502005-06-27 10:55:12 +02002966}
2967
Jens Axboe206dc692006-03-28 13:03:44 +02002968static void
Jeff Moyerb2c18e12009-10-23 17:14:49 -04002969cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboe6d048f52007-04-25 12:44:27 +02002970 struct request *rq)
Jens Axboe206dc692006-03-28 13:03:44 +02002971{
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01002972 sector_t sdist = 0;
Corrado Zoccolo41647e72010-02-27 19:45:40 +01002973 sector_t n_sec = blk_rq_sectors(rq);
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01002974 if (cfqq->last_request_pos) {
2975 if (cfqq->last_request_pos < blk_rq_pos(rq))
2976 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
2977 else
2978 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
2979 }
Jens Axboe206dc692006-03-28 13:03:44 +02002980
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01002981 cfqq->seek_history <<= 1;
Corrado Zoccolo41647e72010-02-27 19:45:40 +01002982 if (blk_queue_nonrot(cfqd->queue))
2983 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
2984 else
2985 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
Jens Axboe206dc692006-03-28 13:03:44 +02002986}
Jens Axboe22e2c502005-06-27 10:55:12 +02002987
2988/*
2989 * Disable idle window if the process thinks too long or seeks so much that
2990 * it doesn't matter
2991 */
2992static void
2993cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Tejun Heoc5869802011-12-14 00:33:41 +01002994 struct cfq_io_cq *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02002995{
Jens Axboe7b679132008-05-30 12:23:07 +02002996 int old_idle, enable_idle;
Jens Axboe1be92f22007-04-19 14:32:26 +02002997
Jens Axboe08717142008-01-28 11:38:15 +01002998 /*
2999 * Don't idle for async or idle io prio class
3000 */
3001 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
Jens Axboe1be92f22007-04-19 14:32:26 +02003002 return;
3003
Jens Axboec265a7f2008-06-26 13:49:33 +02003004 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003005
Corrado Zoccolo76280af2009-11-26 10:02:58 +01003006 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3007 cfq_mark_cfqq_deep(cfqq);
3008
Corrado Zoccolo749ef9f2010-09-20 15:24:50 +02003009 if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3010 enable_idle = 0;
Tejun Heoc5869802011-12-14 00:33:41 +01003011 else if (!atomic_read(&cic->icq.ioc->nr_tasks) ||
3012 !cfqd->cfq_slice_idle ||
3013 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
Jens Axboe22e2c502005-06-27 10:55:12 +02003014 enable_idle = 0;
Shaohua Li383cd722011-07-12 14:24:35 +02003015 else if (sample_valid(cic->ttime.ttime_samples)) {
3016 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
Jens Axboe22e2c502005-06-27 10:55:12 +02003017 enable_idle = 0;
3018 else
3019 enable_idle = 1;
3020 }
3021
Jens Axboe7b679132008-05-30 12:23:07 +02003022 if (old_idle != enable_idle) {
3023 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3024 if (enable_idle)
3025 cfq_mark_cfqq_idle_window(cfqq);
3026 else
3027 cfq_clear_cfqq_idle_window(cfqq);
3028 }
Jens Axboe22e2c502005-06-27 10:55:12 +02003029}
3030
Jens Axboe22e2c502005-06-27 10:55:12 +02003031/*
3032 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3033 * no or if we aren't sure, a 1 will cause a preempt.
3034 */
Jens Axboea6151c32009-10-07 20:02:57 +02003035static bool
Jens Axboe22e2c502005-06-27 10:55:12 +02003036cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
Jens Axboe5e705372006-07-13 12:39:25 +02003037 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003038{
Jens Axboe6d048f52007-04-25 12:44:27 +02003039 struct cfq_queue *cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02003040
Jens Axboe6d048f52007-04-25 12:44:27 +02003041 cfqq = cfqd->active_queue;
3042 if (!cfqq)
Jens Axboea6151c32009-10-07 20:02:57 +02003043 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003044
Jens Axboe6d048f52007-04-25 12:44:27 +02003045 if (cfq_class_idle(new_cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003046 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003047
3048 if (cfq_class_idle(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003049 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003050
Jens Axboe22e2c502005-06-27 10:55:12 +02003051 /*
Divyesh Shah875feb62010-01-06 18:58:20 -08003052 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3053 */
3054 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3055 return false;
3056
3057 /*
Jens Axboe374f84a2006-07-23 01:42:19 +02003058 * if the new request is sync, but the currently running queue is
3059 * not, let the sync request have priority.
3060 */
Jens Axboe5e705372006-07-13 12:39:25 +02003061 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003062 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003063
Vivek Goyal8682e1f2009-12-03 12:59:50 -05003064 if (new_cfqq->cfqg != cfqq->cfqg)
3065 return false;
3066
3067 if (cfq_slice_used(cfqq))
3068 return true;
3069
3070 /* Allow preemption only if we are idling on sync-noidle tree */
3071 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3072 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3073 new_cfqq->service_tree->count == 2 &&
3074 RB_EMPTY_ROOT(&cfqq->sort_list))
3075 return true;
3076
Jens Axboe374f84a2006-07-23 01:42:19 +02003077 /*
Jens Axboeb53d1ed2011-08-19 08:34:48 +02003078 * So both queues are sync. Let the new request get disk time if
3079 * it's a metadata request and the current queue is doing regular IO.
3080 */
Christoph Hellwig65299a32011-08-23 14:50:29 +02003081 if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
Jens Axboeb53d1ed2011-08-19 08:34:48 +02003082 return true;
3083
3084 /*
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003085 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3086 */
3087 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003088 return true;
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003089
Shaohua Lid2d59e12010-11-08 15:01:03 +01003090 /* An idle queue should not be idle now for some reason */
3091 if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3092 return true;
3093
Jens Axboe1e3335d2007-02-14 19:59:49 +01003094 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003095 return false;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003096
3097 /*
3098 * if this request is as-good as one we would expect from the
3099 * current cfqq, let it preempt
3100 */
Shaohua Lie9ce3352010-03-19 08:03:04 +01003101 if (cfq_rq_close(cfqd, cfqq, rq))
Jens Axboea6151c32009-10-07 20:02:57 +02003102 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003103
Jens Axboea6151c32009-10-07 20:02:57 +02003104 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003105}
3106
3107/*
3108 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3109 * let it have half of its nominal slice.
3110 */
3111static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3112{
Shaohua Lidf0793a2012-01-19 09:20:09 +01003113 enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3114
Jens Axboe7b679132008-05-30 12:23:07 +02003115 cfq_log_cfqq(cfqd, cfqq, "preempt");
Shaohua Lidf0793a2012-01-19 09:20:09 +01003116 cfq_slice_expired(cfqd, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003117
Jens Axboebf572252006-07-19 20:29:12 +02003118 /*
Shaohua Lif8ae6e32011-01-14 08:41:02 +01003119 * workload type is changed, don't save slice, otherwise preempt
3120 * doesn't happen
3121 */
Shaohua Lidf0793a2012-01-19 09:20:09 +01003122 if (old_type != cfqq_type(cfqq))
Shaohua Lif8ae6e32011-01-14 08:41:02 +01003123 cfqq->cfqg->saved_workload_slice = 0;
3124
3125 /*
Jens Axboebf572252006-07-19 20:29:12 +02003126 * Put the new queue at the front of the of the current list,
3127 * so we know that it will be selected next.
3128 */
3129 BUG_ON(!cfq_cfqq_on_rr(cfqq));
Jens Axboeedd75ff2007-04-19 12:03:34 +02003130
3131 cfq_service_tree_add(cfqd, cfqq, 1);
Justin TerAvesteda5e0c2011-03-22 21:26:49 +01003132
Justin TerAvest62a37f62011-03-23 08:25:44 +01003133 cfqq->slice_end = 0;
3134 cfq_mark_cfqq_slice_new(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003135}
3136
3137/*
Jens Axboe5e705372006-07-13 12:39:25 +02003138 * Called when a new fs request (rq) is added (to cfqq). Check if there's
Jens Axboe22e2c502005-06-27 10:55:12 +02003139 * something we should do about it
3140 */
3141static void
Jens Axboe5e705372006-07-13 12:39:25 +02003142cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3143 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003144{
Tejun Heoc5869802011-12-14 00:33:41 +01003145 struct cfq_io_cq *cic = RQ_CIC(rq);
Jens Axboe12e9fdd2006-06-01 10:09:56 +02003146
Aaron Carroll45333d52008-08-26 15:52:36 +02003147 cfqd->rq_queued++;
Christoph Hellwig65299a32011-08-23 14:50:29 +02003148 if (rq->cmd_flags & REQ_PRIO)
3149 cfqq->prio_pending++;
Jens Axboe374f84a2006-07-23 01:42:19 +02003150
Shaohua Li383cd722011-07-12 14:24:35 +02003151 cfq_update_io_thinktime(cfqd, cfqq, cic);
Jeff Moyerb2c18e12009-10-23 17:14:49 -04003152 cfq_update_io_seektime(cfqd, cfqq, rq);
Jens Axboe9c2c38a2005-08-24 14:57:54 +02003153 cfq_update_idle_window(cfqd, cfqq, cic);
3154
Jeff Moyerb2c18e12009-10-23 17:14:49 -04003155 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003156
3157 if (cfqq == cfqd->active_queue) {
3158 /*
Jens Axboeb0291952009-04-07 11:38:31 +02003159 * Remember that we saw a request from this process, but
3160 * don't start queuing just yet. Otherwise we risk seeing lots
3161 * of tiny requests, because we disrupt the normal plugging
Jens Axboed6ceb252009-04-14 14:18:16 +02003162 * and merging. If the request is already larger than a single
3163 * page, let it rip immediately. For that case we assume that
Jens Axboe2d870722009-04-15 12:12:46 +02003164 * merging is already done. Ditto for a busy system that
3165 * has other work pending, don't risk delaying until the
3166 * idle timer unplug to continue working.
Jens Axboe22e2c502005-06-27 10:55:12 +02003167 */
Jens Axboed6ceb252009-04-14 14:18:16 +02003168 if (cfq_cfqq_wait_request(cfqq)) {
Jens Axboe2d870722009-04-15 12:12:46 +02003169 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3170 cfqd->busy_queues > 1) {
Divyesh Shah812df482010-04-08 21:15:35 -07003171 cfq_del_timer(cfqd, cfqq);
Gui Jianfeng554554f2009-12-10 09:38:39 +01003172 cfq_clear_cfqq_wait_request(cfqq);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02003173 __blk_run_queue(cfqd->queue);
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003174 } else {
Vivek Goyale98ef892010-06-18 10:39:47 -04003175 cfq_blkiocg_update_idle_time_stats(
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003176 &cfqq->cfqg->blkg);
Vivek Goyalbf7919372009-12-03 12:59:37 -05003177 cfq_mark_cfqq_must_dispatch(cfqq);
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003178 }
Jens Axboed6ceb252009-04-14 14:18:16 +02003179 }
Jens Axboe5e705372006-07-13 12:39:25 +02003180 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
Jens Axboe22e2c502005-06-27 10:55:12 +02003181 /*
3182 * not the active queue - expire current slice if it is
3183 * idle and has expired it's mean thinktime or this new queue
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003184 * has some old slice time left and is of higher priority or
3185 * this new queue is RT and the current one is BE
Jens Axboe22e2c502005-06-27 10:55:12 +02003186 */
3187 cfq_preempt_queue(cfqd, cfqq);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02003188 __blk_run_queue(cfqd->queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02003189 }
3190}
3191
Jens Axboe165125e2007-07-24 09:28:11 +02003192static void cfq_insert_request(struct request_queue *q, struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003193{
Jens Axboeb4878f22005-10-20 16:42:29 +02003194 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +02003195 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003196
Jens Axboe7b679132008-05-30 12:23:07 +02003197 cfq_log_cfqq(cfqd, cfqq, "insert_request");
Tejun Heoc5869802011-12-14 00:33:41 +01003198 cfq_init_prio_data(cfqq, RQ_CIC(rq)->icq.ioc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003199
Jens Axboe30996f42009-10-05 11:03:39 +02003200 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
Jens Axboe22e2c502005-06-27 10:55:12 +02003201 list_add_tail(&rq->queuelist, &cfqq->fifo);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01003202 cfq_add_rq_rb(rq);
Vivek Goyale98ef892010-06-18 10:39:47 -04003203 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
Divyesh Shahcdc11842010-04-08 21:15:10 -07003204 &cfqd->serving_group->blkg, rq_data_dir(rq),
3205 rq_is_sync(rq));
Jens Axboe5e705372006-07-13 12:39:25 +02003206 cfq_rq_enqueued(cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003207}
3208
Aaron Carroll45333d52008-08-26 15:52:36 +02003209/*
3210 * Update hw_tag based on peak queue depth over 50 samples under
3211 * sufficient load.
3212 */
3213static void cfq_update_hw_tag(struct cfq_data *cfqd)
3214{
Shaohua Li1a1238a2009-10-27 08:46:23 +01003215 struct cfq_queue *cfqq = cfqd->active_queue;
3216
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003217 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3218 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003219
3220 if (cfqd->hw_tag == 1)
3221 return;
Aaron Carroll45333d52008-08-26 15:52:36 +02003222
3223 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003224 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
Aaron Carroll45333d52008-08-26 15:52:36 +02003225 return;
3226
Shaohua Li1a1238a2009-10-27 08:46:23 +01003227 /*
3228 * If active queue hasn't enough requests and can idle, cfq might not
3229 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3230 * case
3231 */
3232 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3233 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003234 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
Shaohua Li1a1238a2009-10-27 08:46:23 +01003235 return;
3236
Aaron Carroll45333d52008-08-26 15:52:36 +02003237 if (cfqd->hw_tag_samples++ < 50)
3238 return;
3239
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003240 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
Aaron Carroll45333d52008-08-26 15:52:36 +02003241 cfqd->hw_tag = 1;
3242 else
3243 cfqd->hw_tag = 0;
Aaron Carroll45333d52008-08-26 15:52:36 +02003244}
3245
Vivek Goyal7667aa02009-12-08 17:52:58 -05003246static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3247{
Tejun Heoc5869802011-12-14 00:33:41 +01003248 struct cfq_io_cq *cic = cfqd->active_cic;
Vivek Goyal7667aa02009-12-08 17:52:58 -05003249
Justin TerAvest02a8f012011-02-09 14:20:03 +01003250 /* If the queue already has requests, don't wait */
3251 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3252 return false;
3253
Vivek Goyal7667aa02009-12-08 17:52:58 -05003254 /* If there are other queues in the group, don't wait */
3255 if (cfqq->cfqg->nr_cfqq > 1)
3256 return false;
3257
Shaohua Li7700fc42011-07-12 14:24:56 +02003258 /* the only queue in the group, but think time is big */
3259 if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3260 return false;
3261
Vivek Goyal7667aa02009-12-08 17:52:58 -05003262 if (cfq_slice_used(cfqq))
3263 return true;
3264
3265 /* if slice left is less than think time, wait busy */
Shaohua Li383cd722011-07-12 14:24:35 +02003266 if (cic && sample_valid(cic->ttime.ttime_samples)
3267 && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
Vivek Goyal7667aa02009-12-08 17:52:58 -05003268 return true;
3269
3270 /*
3271 * If think times is less than a jiffy than ttime_mean=0 and above
3272 * will not be true. It might happen that slice has not expired yet
3273 * but will expire soon (4-5 ns) during select_queue(). To cover the
3274 * case where think time is less than a jiffy, mark the queue wait
3275 * busy if only 1 jiffy is left in the slice.
3276 */
3277 if (cfqq->slice_end - jiffies == 1)
3278 return true;
3279
3280 return false;
3281}
3282
Jens Axboe165125e2007-07-24 09:28:11 +02003283static void cfq_completed_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003284{
Jens Axboe5e705372006-07-13 12:39:25 +02003285 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02003286 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe5380a102006-07-13 12:37:56 +02003287 const int sync = rq_is_sync(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02003288 unsigned long now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003289
Jens Axboeb4878f22005-10-20 16:42:29 +02003290 now = jiffies;
Christoph Hellwig33659eb2010-08-07 18:17:56 +02003291 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3292 !!(rq->cmd_flags & REQ_NOIDLE));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003293
Aaron Carroll45333d52008-08-26 15:52:36 +02003294 cfq_update_hw_tag(cfqd);
3295
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003296 WARN_ON(!cfqd->rq_in_driver);
Jens Axboe6d048f52007-04-25 12:44:27 +02003297 WARN_ON(!cfqq->dispatched);
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003298 cfqd->rq_in_driver--;
Jens Axboe6d048f52007-04-25 12:44:27 +02003299 cfqq->dispatched--;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003300 (RQ_CFQG(rq))->dispatched--;
Vivek Goyale98ef892010-06-18 10:39:47 -04003301 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3302 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3303 rq_data_dir(rq), rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003304
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003305 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
Jens Axboe3ed9a292007-04-23 08:33:33 +02003306
Vivek Goyal365722b2009-10-03 15:21:27 +02003307 if (sync) {
Shaohua Lif5f2b6c2011-07-12 14:24:55 +02003308 struct cfq_rb_root *service_tree;
3309
Shaohua Li383cd722011-07-12 14:24:35 +02003310 RQ_CIC(rq)->ttime.last_end_request = now;
Shaohua Lif5f2b6c2011-07-12 14:24:55 +02003311
3312 if (cfq_cfqq_on_rr(cfqq))
3313 service_tree = cfqq->service_tree;
3314 else
3315 service_tree = service_tree_for(cfqq->cfqg,
3316 cfqq_prio(cfqq), cfqq_type(cfqq));
3317 service_tree->ttime.last_end_request = now;
Corrado Zoccolo573412b2009-12-06 11:48:52 +01003318 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3319 cfqd->last_delayed_sync = now;
Vivek Goyal365722b2009-10-03 15:21:27 +02003320 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02003321
Shaohua Li7700fc42011-07-12 14:24:56 +02003322#ifdef CONFIG_CFQ_GROUP_IOSCHED
3323 cfqq->cfqg->ttime.last_end_request = now;
3324#endif
3325
Jens Axboecaaa5f92006-06-16 11:23:00 +02003326 /*
3327 * If this is the active queue, check if it needs to be expired,
3328 * or if we want to idle in case it has no pending requests.
3329 */
3330 if (cfqd->active_queue == cfqq) {
Jens Axboea36e71f2009-04-15 12:15:11 +02003331 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3332
Jens Axboe44f7c162007-01-19 11:51:58 +11003333 if (cfq_cfqq_slice_new(cfqq)) {
3334 cfq_set_prio_slice(cfqd, cfqq);
3335 cfq_clear_cfqq_slice_new(cfqq);
3336 }
Vivek Goyalf75edf22009-12-03 12:59:53 -05003337
3338 /*
Vivek Goyal7667aa02009-12-08 17:52:58 -05003339 * Should we wait for next request to come in before we expire
3340 * the queue.
Vivek Goyalf75edf22009-12-03 12:59:53 -05003341 */
Vivek Goyal7667aa02009-12-08 17:52:58 -05003342 if (cfq_should_wait_busy(cfqd, cfqq)) {
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003343 unsigned long extend_sl = cfqd->cfq_slice_idle;
3344 if (!cfqd->cfq_slice_idle)
3345 extend_sl = cfqd->cfq_group_idle;
3346 cfqq->slice_end = jiffies + extend_sl;
Vivek Goyalf75edf22009-12-03 12:59:53 -05003347 cfq_mark_cfqq_wait_busy(cfqq);
Divyesh Shahb1ffe732010-03-25 15:45:03 +01003348 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
Vivek Goyalf75edf22009-12-03 12:59:53 -05003349 }
3350
Jens Axboea36e71f2009-04-15 12:15:11 +02003351 /*
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003352 * Idling is not enabled on:
3353 * - expired queues
3354 * - idle-priority queues
3355 * - async queues
3356 * - queues with still some requests queued
3357 * - when there is a close cooperator
Jens Axboea36e71f2009-04-15 12:15:11 +02003358 */
Jens Axboe08717142008-01-28 11:38:15 +01003359 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
Vivek Goyale5ff0822010-04-26 19:25:11 +02003360 cfq_slice_expired(cfqd, 1);
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003361 else if (sync && cfqq_empty &&
3362 !cfq_close_cooperator(cfqd, cfqq)) {
Corrado Zoccolo749ef9f2010-09-20 15:24:50 +02003363 cfq_arm_slice_timer(cfqd);
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003364 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02003365 }
Jens Axboe6d048f52007-04-25 12:44:27 +02003366
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003367 if (!cfqd->rq_in_driver)
Jens Axboe23e018a2009-10-05 08:52:35 +02003368 cfq_schedule_dispatch(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003369}
3370
Jens Axboe89850f72006-07-22 16:48:31 +02003371static inline int __cfq_may_queue(struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003372{
Jens Axboe1b379d82009-08-11 08:26:11 +02003373 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
Jens Axboe3b181522005-06-27 10:56:24 +02003374 cfq_mark_cfqq_must_alloc_slice(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003375 return ELV_MQUEUE_MUST;
Jens Axboe3b181522005-06-27 10:56:24 +02003376 }
Jens Axboe22e2c502005-06-27 10:55:12 +02003377
3378 return ELV_MQUEUE_MAY;
Jens Axboe22e2c502005-06-27 10:55:12 +02003379}
3380
Jens Axboe165125e2007-07-24 09:28:11 +02003381static int cfq_may_queue(struct request_queue *q, int rw)
Jens Axboe22e2c502005-06-27 10:55:12 +02003382{
3383 struct cfq_data *cfqd = q->elevator->elevator_data;
3384 struct task_struct *tsk = current;
Tejun Heoc5869802011-12-14 00:33:41 +01003385 struct cfq_io_cq *cic;
Jens Axboe22e2c502005-06-27 10:55:12 +02003386 struct cfq_queue *cfqq;
3387
3388 /*
3389 * don't force setup of a queue from here, as a call to may_queue
3390 * does not necessarily imply that a request actually will be queued.
3391 * so just lookup a possibly existing queue, or return 'may queue'
3392 * if that fails
3393 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01003394 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003395 if (!cic)
3396 return ELV_MQUEUE_MAY;
3397
Jens Axboeb0b78f82009-04-08 10:56:08 +02003398 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
Jens Axboe22e2c502005-06-27 10:55:12 +02003399 if (cfqq) {
Tejun Heoc5869802011-12-14 00:33:41 +01003400 cfq_init_prio_data(cfqq, cic->icq.ioc);
Jens Axboe22e2c502005-06-27 10:55:12 +02003401
Jens Axboe89850f72006-07-22 16:48:31 +02003402 return __cfq_may_queue(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003403 }
3404
3405 return ELV_MQUEUE_MAY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003406}
3407
Linus Torvalds1da177e2005-04-16 15:20:36 -07003408/*
3409 * queue lock held here
3410 */
Jens Axboebb37b942006-12-01 10:42:33 +01003411static void cfq_put_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003412{
Jens Axboe5e705372006-07-13 12:39:25 +02003413 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003414
Jens Axboe5e705372006-07-13 12:39:25 +02003415 if (cfqq) {
Jens Axboe22e2c502005-06-27 10:55:12 +02003416 const int rw = rq_data_dir(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003417
Jens Axboe22e2c502005-06-27 10:55:12 +02003418 BUG_ON(!cfqq->allocated[rw]);
3419 cfqq->allocated[rw]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003420
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02003421 /* Put down rq reference on cfqg */
3422 cfq_put_cfqg(RQ_CFQG(rq));
Tejun Heoa612fdd2011-12-14 00:33:41 +01003423 rq->elv.priv[0] = NULL;
3424 rq->elv.priv[1] = NULL;
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02003425
Linus Torvalds1da177e2005-04-16 15:20:36 -07003426 cfq_put_queue(cfqq);
3427 }
3428}
3429
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003430static struct cfq_queue *
Tejun Heoc5869802011-12-14 00:33:41 +01003431cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003432 struct cfq_queue *cfqq)
3433{
3434 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3435 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
Jeff Moyerb3b6d042009-10-23 17:14:51 -04003436 cfq_mark_cfqq_coop(cfqq->new_cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003437 cfq_put_queue(cfqq);
3438 return cic_to_cfqq(cic, 1);
3439}
3440
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003441/*
3442 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3443 * was the last process referring to said cfqq.
3444 */
3445static struct cfq_queue *
Tejun Heoc5869802011-12-14 00:33:41 +01003446split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003447{
3448 if (cfqq_process_refs(cfqq) == 1) {
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003449 cfqq->pid = current->pid;
3450 cfq_clear_cfqq_coop(cfqq);
Shaohua Liae54abe2010-02-05 13:11:45 +01003451 cfq_clear_cfqq_split_coop(cfqq);
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003452 return cfqq;
3453 }
3454
3455 cic_set_cfqq(cic, NULL, 1);
Shaohua Lid02a2c02010-05-25 10:16:53 +02003456
3457 cfq_put_cooperator(cfqq);
3458
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003459 cfq_put_queue(cfqq);
3460 return NULL;
3461}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003462/*
Jens Axboe22e2c502005-06-27 10:55:12 +02003463 * Allocate cfq data structures associated with this request.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003464 */
Jens Axboe22e2c502005-06-27 10:55:12 +02003465static int
Jens Axboe165125e2007-07-24 09:28:11 +02003466cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003467{
3468 struct cfq_data *cfqd = q->elevator->elevator_data;
Tejun Heof1f8cc92011-12-14 00:33:42 +01003469 struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003470 const int rw = rq_data_dir(rq);
Jens Axboea6151c32009-10-07 20:02:57 +02003471 const bool is_sync = rq_is_sync(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003472 struct cfq_queue *cfqq;
Tejun Heod705ae62012-02-15 09:45:49 +01003473 unsigned int changed;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003474
3475 might_sleep_if(gfp_mask & __GFP_WAIT);
3476
Tejun Heo216284c2011-12-14 00:33:38 +01003477 spin_lock_irq(q->queue_lock);
Tejun Heof1f8cc92011-12-14 00:33:42 +01003478
3479 /* handle changed notifications */
Tejun Heod705ae62012-02-15 09:45:49 +01003480 changed = icq_get_changed(&cic->icq);
3481 if (unlikely(changed & ICQ_IOPRIO_CHANGED))
3482 changed_ioprio(cic);
Tejun Heof1f8cc92011-12-14 00:33:42 +01003483#ifdef CONFIG_CFQ_GROUP_IOSCHED
Tejun Heod705ae62012-02-15 09:45:49 +01003484 if (unlikely(changed & ICQ_CGROUP_CHANGED))
3485 changed_cgroup(cic);
Tejun Heof1f8cc92011-12-14 00:33:42 +01003486#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07003487
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003488new_queue:
Vasily Tarasov91fac312007-04-25 12:29:51 +02003489 cfqq = cic_to_cfqq(cic, is_sync);
Vivek Goyal32f2e802009-07-09 22:13:16 +02003490 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
Tejun Heoc5869802011-12-14 00:33:41 +01003491 cfqq = cfq_get_queue(cfqd, is_sync, cic->icq.ioc, gfp_mask);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003492 cic_set_cfqq(cic, cfqq, is_sync);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003493 } else {
3494 /*
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003495 * If the queue was seeky for too long, break it apart.
3496 */
Shaohua Liae54abe2010-02-05 13:11:45 +01003497 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003498 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3499 cfqq = split_cfqq(cic, cfqq);
3500 if (!cfqq)
3501 goto new_queue;
3502 }
3503
3504 /*
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003505 * Check to see if this queue is scheduled to merge with
3506 * another, closely cooperating queue. The merging of
3507 * queues happens here as it must be done in process context.
3508 * The reference on new_cfqq was taken in merge_cfqqs.
3509 */
3510 if (cfqq->new_cfqq)
3511 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003512 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003513
3514 cfqq->allocated[rw]++;
Jens Axboe5e705372006-07-13 12:39:25 +02003515
Jens Axboe6fae9c22011-03-01 15:04:39 -05003516 cfqq->ref++;
Tejun Heoa612fdd2011-12-14 00:33:41 +01003517 rq->elv.priv[0] = cfqq;
3518 rq->elv.priv[1] = cfq_ref_get_cfqg(cfqq->cfqg);
Tejun Heo216284c2011-12-14 00:33:38 +01003519 spin_unlock_irq(q->queue_lock);
Jens Axboe5e705372006-07-13 12:39:25 +02003520 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003521}
3522
David Howells65f27f32006-11-22 14:55:48 +00003523static void cfq_kick_queue(struct work_struct *work)
Jens Axboe22e2c502005-06-27 10:55:12 +02003524{
David Howells65f27f32006-11-22 14:55:48 +00003525 struct cfq_data *cfqd =
Jens Axboe23e018a2009-10-05 08:52:35 +02003526 container_of(work, struct cfq_data, unplug_work);
Jens Axboe165125e2007-07-24 09:28:11 +02003527 struct request_queue *q = cfqd->queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02003528
Jens Axboe40bb54d2009-04-15 12:11:10 +02003529 spin_lock_irq(q->queue_lock);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02003530 __blk_run_queue(cfqd->queue);
Jens Axboe40bb54d2009-04-15 12:11:10 +02003531 spin_unlock_irq(q->queue_lock);
Jens Axboe22e2c502005-06-27 10:55:12 +02003532}
3533
3534/*
3535 * Timer running if the active_queue is currently idling inside its time slice
3536 */
3537static void cfq_idle_slice_timer(unsigned long data)
3538{
3539 struct cfq_data *cfqd = (struct cfq_data *) data;
3540 struct cfq_queue *cfqq;
3541 unsigned long flags;
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11003542 int timed_out = 1;
Jens Axboe22e2c502005-06-27 10:55:12 +02003543
Jens Axboe7b679132008-05-30 12:23:07 +02003544 cfq_log(cfqd, "idle timer fired");
3545
Jens Axboe22e2c502005-06-27 10:55:12 +02003546 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3547
Jens Axboefe094d92008-01-31 13:08:54 +01003548 cfqq = cfqd->active_queue;
3549 if (cfqq) {
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11003550 timed_out = 0;
3551
Jens Axboe22e2c502005-06-27 10:55:12 +02003552 /*
Jens Axboeb0291952009-04-07 11:38:31 +02003553 * We saw a request before the queue expired, let it through
3554 */
3555 if (cfq_cfqq_must_dispatch(cfqq))
3556 goto out_kick;
3557
3558 /*
Jens Axboe22e2c502005-06-27 10:55:12 +02003559 * expired
3560 */
Jens Axboe44f7c162007-01-19 11:51:58 +11003561 if (cfq_slice_used(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02003562 goto expire;
3563
3564 /*
3565 * only expire and reinvoke request handler, if there are
3566 * other queues with pending requests
3567 */
Jens Axboecaaa5f92006-06-16 11:23:00 +02003568 if (!cfqd->busy_queues)
Jens Axboe22e2c502005-06-27 10:55:12 +02003569 goto out_cont;
Jens Axboe22e2c502005-06-27 10:55:12 +02003570
3571 /*
3572 * not expired and it has a request pending, let it dispatch
3573 */
Jens Axboe75e50982009-04-07 08:56:14 +02003574 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +02003575 goto out_kick;
Corrado Zoccolo76280af2009-11-26 10:02:58 +01003576
3577 /*
3578 * Queue depth flag is reset only when the idle didn't succeed
3579 */
3580 cfq_clear_cfqq_deep(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003581 }
3582expire:
Vivek Goyale5ff0822010-04-26 19:25:11 +02003583 cfq_slice_expired(cfqd, timed_out);
Jens Axboe22e2c502005-06-27 10:55:12 +02003584out_kick:
Jens Axboe23e018a2009-10-05 08:52:35 +02003585 cfq_schedule_dispatch(cfqd);
Jens Axboe22e2c502005-06-27 10:55:12 +02003586out_cont:
3587 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3588}
3589
Jens Axboe3b181522005-06-27 10:56:24 +02003590static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3591{
3592 del_timer_sync(&cfqd->idle_slice_timer);
Jens Axboe23e018a2009-10-05 08:52:35 +02003593 cancel_work_sync(&cfqd->unplug_work);
Jens Axboe3b181522005-06-27 10:56:24 +02003594}
Jens Axboe22e2c502005-06-27 10:55:12 +02003595
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003596static void cfq_put_async_queues(struct cfq_data *cfqd)
3597{
3598 int i;
3599
3600 for (i = 0; i < IOPRIO_BE_NR; i++) {
3601 if (cfqd->async_cfqq[0][i])
3602 cfq_put_queue(cfqd->async_cfqq[0][i]);
3603 if (cfqd->async_cfqq[1][i])
3604 cfq_put_queue(cfqd->async_cfqq[1][i]);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003605 }
Oleg Nesterov2389d1e2007-11-05 08:58:05 +01003606
3607 if (cfqd->async_idle_cfqq)
3608 cfq_put_queue(cfqd->async_idle_cfqq);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003609}
3610
Jens Axboeb374d182008-10-31 10:05:07 +01003611static void cfq_exit_queue(struct elevator_queue *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003612{
Jens Axboe22e2c502005-06-27 10:55:12 +02003613 struct cfq_data *cfqd = e->elevator_data;
Jens Axboe165125e2007-07-24 09:28:11 +02003614 struct request_queue *q = cfqd->queue;
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003615 bool wait = false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003616
Jens Axboe3b181522005-06-27 10:56:24 +02003617 cfq_shutdown_timer_wq(cfqd);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003618
Al Virod9ff4182006-03-18 13:51:22 -05003619 spin_lock_irq(q->queue_lock);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003620
Al Virod9ff4182006-03-18 13:51:22 -05003621 if (cfqd->active_queue)
Vivek Goyale5ff0822010-04-26 19:25:11 +02003622 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003623
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003624 cfq_put_async_queues(cfqd);
Vivek Goyalb1c35762009-12-03 12:59:47 -05003625 cfq_release_cfq_groups(cfqd);
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003626
3627 /*
3628 * If there are groups which we could not unlink from blkcg list,
3629 * wait for a rcu period for them to be freed.
3630 */
3631 if (cfqd->nr_blkcg_linked_grps)
3632 wait = true;
Jens Axboe15c31be2007-07-10 13:43:25 +02003633
Al Virod9ff4182006-03-18 13:51:22 -05003634 spin_unlock_irq(q->queue_lock);
Al Viroa90d7422006-03-18 12:05:37 -05003635
3636 cfq_shutdown_timer_wq(cfqd);
3637
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003638 /*
3639 * Wait for cfqg->blkg->key accessors to exit their grace periods.
3640 * Do this wait only if there are other unlinked groups out
3641 * there. This can happen if cgroup deletion path claimed the
3642 * responsibility of cleaning up a group before queue cleanup code
3643 * get to the group.
3644 *
3645 * Do not call synchronize_rcu() unconditionally as there are drivers
3646 * which create/delete request queue hundreds of times during scan/boot
3647 * and synchronize_rcu() can take significant time and slow down boot.
3648 */
3649 if (wait)
3650 synchronize_rcu();
Vivek Goyal2abae552011-05-23 10:02:19 +02003651
3652#ifdef CONFIG_CFQ_GROUP_IOSCHED
3653 /* Free up per cpu stats for root group */
3654 free_percpu(cfqd->root_group.blkg.stats_cpu);
3655#endif
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003656 kfree(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003657}
3658
Jens Axboe165125e2007-07-24 09:28:11 +02003659static void *cfq_init_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003660{
3661 struct cfq_data *cfqd;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01003662 int i, j;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003663 struct cfq_group *cfqg;
Vivek Goyal615f0252009-12-03 12:59:39 -05003664 struct cfq_rb_root *st;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003665
Christoph Lameter94f60302007-07-17 04:03:29 -07003666 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
Tejun Heoa73f7302011-12-14 00:33:37 +01003667 if (!cfqd)
Jens Axboebc1c1162006-06-08 08:49:06 +02003668 return NULL;
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04003669
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05003670 /* Init root service tree */
3671 cfqd->grp_service_tree = CFQ_RB_ROOT;
3672
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003673 /* Init root group */
3674 cfqg = &cfqd->root_group;
Vivek Goyal615f0252009-12-03 12:59:39 -05003675 for_each_cfqg_st(cfqg, i, j, st)
3676 *st = CFQ_RB_ROOT;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05003677 RB_CLEAR_NODE(&cfqg->rb_node);
Jens Axboe26a2ac02009-04-23 12:13:27 +02003678
Vivek Goyal25bc6b02009-12-03 12:59:43 -05003679 /* Give preference to root group over other groups */
3680 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3681
Vivek Goyal25fb5162009-12-03 12:59:46 -05003682#ifdef CONFIG_CFQ_GROUP_IOSCHED
Vivek Goyalb1c35762009-12-03 12:59:47 -05003683 /*
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003684 * Set root group reference to 2. One reference will be dropped when
3685 * all groups on cfqd->cfqg_list are being deleted during queue exit.
3686 * Other reference will remain there as we don't want to delete this
3687 * group as it is statically allocated and gets destroyed when
3688 * throtl_data goes away.
Vivek Goyalb1c35762009-12-03 12:59:47 -05003689 */
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003690 cfqg->ref = 2;
Vivek Goyal5624a4e2011-05-19 15:38:28 -04003691
3692 if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
3693 kfree(cfqg);
3694 kfree(cfqd);
3695 return NULL;
3696 }
3697
Vivek Goyaldcf097b2010-04-22 11:54:52 -04003698 rcu_read_lock();
Vivek Goyal5624a4e2011-05-19 15:38:28 -04003699
Vivek Goyale98ef892010-06-18 10:39:47 -04003700 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3701 (void *)cfqd, 0);
Vivek Goyaldcf097b2010-04-22 11:54:52 -04003702 rcu_read_unlock();
Vivek Goyal56edf7d2011-05-19 15:38:22 -04003703 cfqd->nr_blkcg_linked_grps++;
3704
3705 /* Add group on cfqd->cfqg_list */
3706 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
Vivek Goyal25fb5162009-12-03 12:59:46 -05003707#endif
Jens Axboe26a2ac02009-04-23 12:13:27 +02003708 /*
3709 * Not strictly needed (since RB_ROOT just clears the node and we
3710 * zeroed cfqd on alloc), but better be safe in case someone decides
3711 * to add magic to the rb code
3712 */
3713 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3714 cfqd->prio_trees[i] = RB_ROOT;
3715
Jens Axboe6118b702009-06-30 09:34:12 +02003716 /*
3717 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3718 * Grab a permanent reference to it, so that the normal code flow
3719 * will not attempt to free it.
3720 */
3721 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
Shaohua Li30d7b942011-01-07 08:46:59 +01003722 cfqd->oom_cfqq.ref++;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003723 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
Jens Axboe6118b702009-06-30 09:34:12 +02003724
Linus Torvalds1da177e2005-04-16 15:20:36 -07003725 cfqd->queue = q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003726
Jens Axboe22e2c502005-06-27 10:55:12 +02003727 init_timer(&cfqd->idle_slice_timer);
3728 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3729 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3730
Jens Axboe23e018a2009-10-05 08:52:35 +02003731 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02003732
Linus Torvalds1da177e2005-04-16 15:20:36 -07003733 cfqd->cfq_quantum = cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +02003734 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3735 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
Linus Torvalds1da177e2005-04-16 15:20:36 -07003736 cfqd->cfq_back_max = cfq_back_max;
3737 cfqd->cfq_back_penalty = cfq_back_penalty;
Jens Axboe22e2c502005-06-27 10:55:12 +02003738 cfqd->cfq_slice[0] = cfq_slice_async;
3739 cfqd->cfq_slice[1] = cfq_slice_sync;
3740 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3741 cfqd->cfq_slice_idle = cfq_slice_idle;
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003742 cfqd->cfq_group_idle = cfq_group_idle;
Jens Axboe963b72f2009-10-03 19:42:18 +02003743 cfqd->cfq_latency = 1;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003744 cfqd->hw_tag = -1;
Corrado Zoccoloedc71132009-12-09 20:56:04 +01003745 /*
3746 * we optimistically start assuming sync ops weren't delayed in last
3747 * second, in order to have larger depth for async operations.
3748 */
Corrado Zoccolo573412b2009-12-06 11:48:52 +01003749 cfqd->last_delayed_sync = jiffies - HZ;
Jens Axboebc1c1162006-06-08 08:49:06 +02003750 return cfqd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003751}
3752
Linus Torvalds1da177e2005-04-16 15:20:36 -07003753/*
3754 * sysfs parts below -->
3755 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003756static ssize_t
3757cfq_var_show(unsigned int var, char *page)
3758{
3759 return sprintf(page, "%d\n", var);
3760}
3761
3762static ssize_t
3763cfq_var_store(unsigned int *var, const char *page, size_t count)
3764{
3765 char *p = (char *) page;
3766
3767 *var = simple_strtoul(p, &p, 10);
3768 return count;
3769}
3770
Linus Torvalds1da177e2005-04-16 15:20:36 -07003771#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
Jens Axboeb374d182008-10-31 10:05:07 +01003772static ssize_t __FUNC(struct elevator_queue *e, char *page) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003773{ \
Al Viro3d1ab402006-03-18 18:35:43 -05003774 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003775 unsigned int __data = __VAR; \
3776 if (__CONV) \
3777 __data = jiffies_to_msecs(__data); \
3778 return cfq_var_show(__data, (page)); \
3779}
3780SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003781SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3782SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
Al Viroe572ec72006-03-18 22:27:18 -05003783SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3784SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003785SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003786SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003787SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3788SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3789SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
Jens Axboe963b72f2009-10-03 19:42:18 +02003790SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003791#undef SHOW_FUNCTION
3792
3793#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
Jens Axboeb374d182008-10-31 10:05:07 +01003794static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003795{ \
Al Viro3d1ab402006-03-18 18:35:43 -05003796 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003797 unsigned int __data; \
3798 int ret = cfq_var_store(&__data, (page), count); \
3799 if (__data < (MIN)) \
3800 __data = (MIN); \
3801 else if (__data > (MAX)) \
3802 __data = (MAX); \
3803 if (__CONV) \
3804 *(__PTR) = msecs_to_jiffies(__data); \
3805 else \
3806 *(__PTR) = __data; \
3807 return ret; \
3808}
3809STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01003810STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3811 UINT_MAX, 1);
3812STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3813 UINT_MAX, 1);
Al Viroe572ec72006-03-18 22:27:18 -05003814STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01003815STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3816 UINT_MAX, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003817STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003818STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003819STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3820STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
Jens Axboefe094d92008-01-31 13:08:54 +01003821STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3822 UINT_MAX, 0);
Jens Axboe963b72f2009-10-03 19:42:18 +02003823STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003824#undef STORE_FUNCTION
3825
Al Viroe572ec72006-03-18 22:27:18 -05003826#define CFQ_ATTR(name) \
3827 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
Jens Axboe3b181522005-06-27 10:56:24 +02003828
Al Viroe572ec72006-03-18 22:27:18 -05003829static struct elv_fs_entry cfq_attrs[] = {
3830 CFQ_ATTR(quantum),
Al Viroe572ec72006-03-18 22:27:18 -05003831 CFQ_ATTR(fifo_expire_sync),
3832 CFQ_ATTR(fifo_expire_async),
3833 CFQ_ATTR(back_seek_max),
3834 CFQ_ATTR(back_seek_penalty),
3835 CFQ_ATTR(slice_sync),
3836 CFQ_ATTR(slice_async),
3837 CFQ_ATTR(slice_async_rq),
3838 CFQ_ATTR(slice_idle),
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003839 CFQ_ATTR(group_idle),
Jens Axboe963b72f2009-10-03 19:42:18 +02003840 CFQ_ATTR(low_latency),
Al Viroe572ec72006-03-18 22:27:18 -05003841 __ATTR_NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07003842};
3843
Linus Torvalds1da177e2005-04-16 15:20:36 -07003844static struct elevator_type iosched_cfq = {
3845 .ops = {
3846 .elevator_merge_fn = cfq_merge,
3847 .elevator_merged_fn = cfq_merged_request,
3848 .elevator_merge_req_fn = cfq_merged_requests,
Jens Axboeda775262006-12-20 11:04:12 +01003849 .elevator_allow_merge_fn = cfq_allow_merge,
Divyesh Shah812d4022010-04-08 21:14:23 -07003850 .elevator_bio_merged_fn = cfq_bio_merged,
Jens Axboeb4878f22005-10-20 16:42:29 +02003851 .elevator_dispatch_fn = cfq_dispatch_requests,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003852 .elevator_add_req_fn = cfq_insert_request,
Jens Axboeb4878f22005-10-20 16:42:29 +02003853 .elevator_activate_req_fn = cfq_activate_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003854 .elevator_deactivate_req_fn = cfq_deactivate_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003855 .elevator_completed_req_fn = cfq_completed_request,
Jens Axboe21183b02006-07-13 12:33:14 +02003856 .elevator_former_req_fn = elv_rb_former_request,
3857 .elevator_latter_req_fn = elv_rb_latter_request,
Tejun Heo9b84cac2011-12-14 00:33:42 +01003858 .elevator_init_icq_fn = cfq_init_icq,
Tejun Heo7e5a8792011-12-14 00:33:42 +01003859 .elevator_exit_icq_fn = cfq_exit_icq,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003860 .elevator_set_req_fn = cfq_set_request,
3861 .elevator_put_req_fn = cfq_put_request,
3862 .elevator_may_queue_fn = cfq_may_queue,
3863 .elevator_init_fn = cfq_init_queue,
3864 .elevator_exit_fn = cfq_exit_queue,
3865 },
Tejun Heo3d3c2372011-12-14 00:33:42 +01003866 .icq_size = sizeof(struct cfq_io_cq),
3867 .icq_align = __alignof__(struct cfq_io_cq),
Al Viro3d1ab402006-03-18 18:35:43 -05003868 .elevator_attrs = cfq_attrs,
Tejun Heo3d3c2372011-12-14 00:33:42 +01003869 .elevator_name = "cfq",
Linus Torvalds1da177e2005-04-16 15:20:36 -07003870 .elevator_owner = THIS_MODULE,
3871};
3872
Vivek Goyal3e252062009-12-04 10:36:42 -05003873#ifdef CONFIG_CFQ_GROUP_IOSCHED
3874static struct blkio_policy_type blkio_policy_cfq = {
3875 .ops = {
3876 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
3877 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
3878 },
Vivek Goyal062a6442010-09-15 17:06:33 -04003879 .plid = BLKIO_POLICY_PROP,
Vivek Goyal3e252062009-12-04 10:36:42 -05003880};
3881#else
3882static struct blkio_policy_type blkio_policy_cfq;
3883#endif
3884
Linus Torvalds1da177e2005-04-16 15:20:36 -07003885static int __init cfq_init(void)
3886{
Tejun Heo3d3c2372011-12-14 00:33:42 +01003887 int ret;
3888
Jens Axboe22e2c502005-06-27 10:55:12 +02003889 /*
3890 * could be 0 on HZ < 1000 setups
3891 */
3892 if (!cfq_slice_async)
3893 cfq_slice_async = 1;
3894 if (!cfq_slice_idle)
3895 cfq_slice_idle = 1;
3896
Vivek Goyal80bdf0c2010-08-23 12:24:26 +02003897#ifdef CONFIG_CFQ_GROUP_IOSCHED
3898 if (!cfq_group_idle)
3899 cfq_group_idle = 1;
3900#else
3901 cfq_group_idle = 0;
3902#endif
Tejun Heo3d3c2372011-12-14 00:33:42 +01003903 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3904 if (!cfq_pool)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003905 return -ENOMEM;
3906
Tejun Heo3d3c2372011-12-14 00:33:42 +01003907 ret = elv_register(&iosched_cfq);
3908 if (ret) {
3909 kmem_cache_destroy(cfq_pool);
3910 return ret;
3911 }
Tejun Heo3d3c2372011-12-14 00:33:42 +01003912
Vivek Goyal3e252062009-12-04 10:36:42 -05003913 blkio_policy_register(&blkio_policy_cfq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003914
Adrian Bunk2fdd82b2007-12-12 18:51:56 +01003915 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003916}
3917
3918static void __exit cfq_exit(void)
3919{
Vivek Goyal3e252062009-12-04 10:36:42 -05003920 blkio_policy_unregister(&blkio_policy_cfq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003921 elv_unregister(&iosched_cfq);
Tejun Heo3d3c2372011-12-14 00:33:42 +01003922 kmem_cache_destroy(cfq_pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003923}
3924
3925module_init(cfq_init);
3926module_exit(cfq_exit);
3927
3928MODULE_AUTHOR("Jens Axboe");
3929MODULE_LICENSE("GPL");
3930MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");