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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>
Al Viro1cc9be62006-03-18 12:29:52 -050010#include <linux/blkdev.h>
11#include <linux/elevator.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/rbtree.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020013#include <linux/ioprio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
15/*
16 * tunables
17 */
Jens Axboefe094d92008-01-31 13:08:54 +010018/* max queue in one round of service */
19static const int cfq_quantum = 4;
Arjan van de Ven64100092006-01-06 09:46:02 +010020static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
Jens Axboefe094d92008-01-31 13:08:54 +010021/* maximum backwards seek, in KiB */
22static const int cfq_back_max = 16 * 1024;
23/* penalty of a backwards seek */
24static const int cfq_back_penalty = 2;
Arjan van de Ven64100092006-01-06 09:46:02 +010025static const int cfq_slice_sync = HZ / 10;
Jens Axboe3b181522005-06-27 10:56:24 +020026static int cfq_slice_async = HZ / 25;
Arjan van de Ven64100092006-01-06 09:46:02 +010027static const int cfq_slice_async_rq = 2;
Jens Axboecaaa5f92006-06-16 11:23:00 +020028static int cfq_slice_idle = HZ / 125;
Jens Axboe22e2c502005-06-27 10:55:12 +020029
Jens Axboed9e76202007-04-20 14:27:50 +020030/*
Jens Axboe08717142008-01-28 11:38:15 +010031 * offset from end of service tree
Jens Axboed9e76202007-04-20 14:27:50 +020032 */
Jens Axboe08717142008-01-28 11:38:15 +010033#define CFQ_IDLE_DELAY (HZ / 5)
Jens Axboed9e76202007-04-20 14:27:50 +020034
35/*
36 * below this threshold, we consider thinktime immediate
37 */
38#define CFQ_MIN_TT (2)
39
Jens Axboe22e2c502005-06-27 10:55:12 +020040#define CFQ_SLICE_SCALE (5)
41
Jens Axboefe094d92008-01-31 13:08:54 +010042#define RQ_CIC(rq) \
43 ((struct cfq_io_context *) (rq)->elevator_private)
Jens Axboe5e705372006-07-13 12:39:25 +020044#define RQ_CFQQ(rq) ((rq)->elevator_private2)
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
Christoph Lametere18b8902006-12-06 20:33:20 -080046static struct kmem_cache *cfq_pool;
47static struct kmem_cache *cfq_ioc_pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Jens Axboe4050cf12006-07-19 05:07:12 +020049static DEFINE_PER_CPU(unsigned long, ioc_count);
Al Viro334e94d2006-03-18 15:05:53 -050050static struct completion *ioc_gone;
51
Jens Axboe22e2c502005-06-27 10:55:12 +020052#define CFQ_PRIO_LISTS IOPRIO_BE_NR
53#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
Jens Axboe22e2c502005-06-27 10:55:12 +020054#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
55
Jens Axboe3b181522005-06-27 10:56:24 +020056#define ASYNC (0)
57#define SYNC (1)
58
Jens Axboe206dc692006-03-28 13:03:44 +020059#define sample_valid(samples) ((samples) > 80)
60
Jens Axboe22e2c502005-06-27 10:55:12 +020061/*
Jens Axboecc09e292007-04-26 12:53:50 +020062 * Most of our rbtree usage is for sorting with min extraction, so
63 * if we cache the leftmost node we don't have to walk down the tree
64 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
65 * move this into the elevator for the rq sorting as well.
66 */
67struct cfq_rb_root {
68 struct rb_root rb;
69 struct rb_node *left;
70};
71#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
72
73/*
Jens Axboe22e2c502005-06-27 10:55:12 +020074 * Per block device queue structure
75 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070076struct cfq_data {
Jens Axboe165125e2007-07-24 09:28:11 +020077 struct request_queue *queue;
Jens Axboe22e2c502005-06-27 10:55:12 +020078
79 /*
80 * rr list of queues with requests and the count of them
81 */
Jens Axboecc09e292007-04-26 12:53:50 +020082 struct cfq_rb_root service_tree;
Jens Axboe22e2c502005-06-27 10:55:12 +020083 unsigned int busy_queues;
84
Jens Axboe22e2c502005-06-27 10:55:12 +020085 int rq_in_driver;
Jens Axboe3ed9a292007-04-23 08:33:33 +020086 int sync_flight;
Jens Axboe25776e32006-06-01 10:12:26 +020087 int hw_tag;
Jens Axboe22e2c502005-06-27 10:55:12 +020088
89 /*
Jens Axboe22e2c502005-06-27 10:55:12 +020090 * idle window management
91 */
92 struct timer_list idle_slice_timer;
93 struct work_struct unplug_work;
94
95 struct cfq_queue *active_queue;
96 struct cfq_io_context *active_cic;
Jens Axboe22e2c502005-06-27 10:55:12 +020097
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +020098 /*
99 * async queue for each priority case
100 */
101 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
102 struct cfq_queue *async_idle_cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +0200103
Jens Axboe6d048f52007-04-25 12:44:27 +0200104 sector_t last_position;
Jens Axboe22e2c502005-06-27 10:55:12 +0200105 unsigned long last_end_request;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 /*
108 * tunables, see top of file
109 */
110 unsigned int cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +0200111 unsigned int cfq_fifo_expire[2];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 unsigned int cfq_back_penalty;
113 unsigned int cfq_back_max;
Jens Axboe22e2c502005-06-27 10:55:12 +0200114 unsigned int cfq_slice[2];
115 unsigned int cfq_slice_async_rq;
116 unsigned int cfq_slice_idle;
Al Virod9ff4182006-03-18 13:51:22 -0500117
118 struct list_head cic_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119};
120
Jens Axboe22e2c502005-06-27 10:55:12 +0200121/*
122 * Per process-grouping structure
123 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124struct cfq_queue {
125 /* reference count */
126 atomic_t ref;
127 /* parent cfq_data */
128 struct cfq_data *cfqd;
Jens Axboed9e76202007-04-20 14:27:50 +0200129 /* service_tree member */
130 struct rb_node rb_node;
131 /* service_tree key */
132 unsigned long rb_key;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 /* sorted list of pending requests */
134 struct rb_root sort_list;
135 /* if fifo isn't expired, next request to serve */
Jens Axboe5e705372006-07-13 12:39:25 +0200136 struct request *next_rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 /* requests queued in sort_list */
138 int queued[2];
139 /* currently allocated requests */
140 int allocated[2];
Jens Axboe374f84a2006-07-23 01:42:19 +0200141 /* pending metadata requests */
142 int meta_pending;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 /* fifo list of requests in sort_list */
Jens Axboe22e2c502005-06-27 10:55:12 +0200144 struct list_head fifo;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Jens Axboe22e2c502005-06-27 10:55:12 +0200146 unsigned long slice_end;
Jens Axboec5b680f2007-01-19 11:56:49 +1100147 long slice_resid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
Jens Axboe6d048f52007-04-25 12:44:27 +0200149 /* number of requests that are on the dispatch list or inside driver */
150 int dispatched;
Jens Axboe22e2c502005-06-27 10:55:12 +0200151
152 /* io prio of this group */
153 unsigned short ioprio, org_ioprio;
154 unsigned short ioprio_class, org_ioprio_class;
155
Jens Axboe3b181522005-06-27 10:56:24 +0200156 /* various state flags, see below */
157 unsigned int flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158};
159
Jens Axboe3b181522005-06-27 10:56:24 +0200160enum cfqq_state_flags {
Jens Axboeb0b8d742007-01-19 11:35:30 +1100161 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
162 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
163 CFQ_CFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
164 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
165 CFQ_CFQQ_FLAG_must_dispatch, /* must dispatch, even if expired */
166 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
167 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
168 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
169 CFQ_CFQQ_FLAG_queue_new, /* queue never been serviced */
Jens Axboe44f7c162007-01-19 11:51:58 +1100170 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
Vasily Tarasov91fac312007-04-25 12:29:51 +0200171 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
Jens Axboe3b181522005-06-27 10:56:24 +0200172};
173
174#define CFQ_CFQQ_FNS(name) \
175static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
176{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100177 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200178} \
179static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
180{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100181 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200182} \
183static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
184{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100185 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
Jens Axboe3b181522005-06-27 10:56:24 +0200186}
187
188CFQ_CFQQ_FNS(on_rr);
189CFQ_CFQQ_FNS(wait_request);
190CFQ_CFQQ_FNS(must_alloc);
191CFQ_CFQQ_FNS(must_alloc_slice);
192CFQ_CFQQ_FNS(must_dispatch);
193CFQ_CFQQ_FNS(fifo_expire);
194CFQ_CFQQ_FNS(idle_window);
195CFQ_CFQQ_FNS(prio_changed);
Jens Axboe53b03742006-07-28 09:48:51 +0200196CFQ_CFQQ_FNS(queue_new);
Jens Axboe44f7c162007-01-19 11:51:58 +1100197CFQ_CFQQ_FNS(slice_new);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200198CFQ_CFQQ_FNS(sync);
Jens Axboe3b181522005-06-27 10:56:24 +0200199#undef CFQ_CFQQ_FNS
200
Jens Axboe165125e2007-07-24 09:28:11 +0200201static void cfq_dispatch_insert(struct request_queue *, struct request *);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200202static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
Jens Axboefd0928d2008-01-24 08:52:45 +0100203 struct io_context *, gfp_t);
Jens Axboe4ac845a2008-01-24 08:44:49 +0100204static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
Vasily Tarasov91fac312007-04-25 12:29:51 +0200205 struct io_context *);
206
207static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
208 int is_sync)
209{
210 return cic->cfqq[!!is_sync];
211}
212
213static inline void cic_set_cfqq(struct cfq_io_context *cic,
214 struct cfq_queue *cfqq, int is_sync)
215{
216 cic->cfqq[!!is_sync] = cfqq;
217}
218
219/*
220 * We regard a request as SYNC, if it's either a read or has the SYNC bit
221 * set (in which case it could also be direct WRITE).
222 */
223static inline int cfq_bio_sync(struct bio *bio)
224{
225 if (bio_data_dir(bio) == READ || bio_sync(bio))
226 return 1;
227
228 return 0;
229}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231/*
Andrew Morton99f95e52005-06-27 20:14:05 -0700232 * scheduler run of queue, if there are requests pending and no one in the
233 * driver that will restart queueing
234 */
235static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
236{
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100237 if (cfqd->busy_queues)
Andrew Morton99f95e52005-06-27 20:14:05 -0700238 kblockd_schedule_work(&cfqd->unplug_work);
239}
240
Jens Axboe165125e2007-07-24 09:28:11 +0200241static int cfq_queue_empty(struct request_queue *q)
Andrew Morton99f95e52005-06-27 20:14:05 -0700242{
243 struct cfq_data *cfqd = q->elevator->elevator_data;
244
Jens Axboeb4878f22005-10-20 16:42:29 +0200245 return !cfqd->busy_queues;
Andrew Morton99f95e52005-06-27 20:14:05 -0700246}
247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248/*
Jens Axboe44f7c162007-01-19 11:51:58 +1100249 * Scale schedule slice based on io priority. Use the sync time slice only
250 * if a queue is marked sync and has sync io queued. A sync queue with async
251 * io only, should not get full sync slice length.
252 */
Jens Axboed9e76202007-04-20 14:27:50 +0200253static inline int cfq_prio_slice(struct cfq_data *cfqd, int sync,
254 unsigned short prio)
255{
256 const int base_slice = cfqd->cfq_slice[sync];
257
258 WARN_ON(prio >= IOPRIO_BE_NR);
259
260 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
261}
262
Jens Axboe44f7c162007-01-19 11:51:58 +1100263static inline int
264cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
265{
Jens Axboed9e76202007-04-20 14:27:50 +0200266 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
Jens Axboe44f7c162007-01-19 11:51:58 +1100267}
268
269static inline void
270cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
271{
272 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
273}
274
275/*
276 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
277 * isn't valid until the first request from the dispatch is activated
278 * and the slice time set.
279 */
280static inline int cfq_slice_used(struct cfq_queue *cfqq)
281{
282 if (cfq_cfqq_slice_new(cfqq))
283 return 0;
284 if (time_before(jiffies, cfqq->slice_end))
285 return 0;
286
287 return 1;
288}
289
290/*
Jens Axboe5e705372006-07-13 12:39:25 +0200291 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 * We choose the request that is closest to the head right now. Distance
Andreas Mohre8a99052006-03-28 08:59:49 +0200293 * behind the head is penalized and only allowed to a certain extent.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 */
Jens Axboe5e705372006-07-13 12:39:25 +0200295static struct request *
296cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297{
298 sector_t last, s1, s2, d1 = 0, d2 = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 unsigned long back_max;
Andreas Mohre8a99052006-03-28 08:59:49 +0200300#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
301#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
302 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
Jens Axboe5e705372006-07-13 12:39:25 +0200304 if (rq1 == NULL || rq1 == rq2)
305 return rq2;
306 if (rq2 == NULL)
307 return rq1;
Jens Axboe9c2c38a2005-08-24 14:57:54 +0200308
Jens Axboe5e705372006-07-13 12:39:25 +0200309 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
310 return rq1;
311 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
312 return rq2;
Jens Axboe374f84a2006-07-23 01:42:19 +0200313 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
314 return rq1;
315 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
316 return rq2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317
Jens Axboe5e705372006-07-13 12:39:25 +0200318 s1 = rq1->sector;
319 s2 = rq2->sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
Jens Axboe6d048f52007-04-25 12:44:27 +0200321 last = cfqd->last_position;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 /*
324 * by definition, 1KiB is 2 sectors
325 */
326 back_max = cfqd->cfq_back_max * 2;
327
328 /*
329 * Strict one way elevator _except_ in the case where we allow
330 * short backward seeks which are biased as twice the cost of a
331 * similar forward seek.
332 */
333 if (s1 >= last)
334 d1 = s1 - last;
335 else if (s1 + back_max >= last)
336 d1 = (last - s1) * cfqd->cfq_back_penalty;
337 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200338 wrap |= CFQ_RQ1_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339
340 if (s2 >= last)
341 d2 = s2 - last;
342 else if (s2 + back_max >= last)
343 d2 = (last - s2) * cfqd->cfq_back_penalty;
344 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200345 wrap |= CFQ_RQ2_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346
347 /* Found required data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348
Andreas Mohre8a99052006-03-28 08:59:49 +0200349 /*
350 * By doing switch() on the bit mask "wrap" we avoid having to
351 * check two variables for all permutations: --> faster!
352 */
353 switch (wrap) {
Jens Axboe5e705372006-07-13 12:39:25 +0200354 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200355 if (d1 < d2)
Jens Axboe5e705372006-07-13 12:39:25 +0200356 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200357 else if (d2 < d1)
Jens Axboe5e705372006-07-13 12:39:25 +0200358 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200359 else {
360 if (s1 >= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200361 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200362 else
Jens Axboe5e705372006-07-13 12:39:25 +0200363 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200364 }
365
366 case CFQ_RQ2_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200367 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200368 case CFQ_RQ1_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200369 return rq2;
370 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200371 default:
372 /*
373 * Since both rqs are wrapped,
374 * start with the one that's further behind head
375 * (--> only *one* back seek required),
376 * since back seek takes more time than forward.
377 */
378 if (s1 <= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200379 return rq1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 else
Jens Axboe5e705372006-07-13 12:39:25 +0200381 return rq2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 }
383}
384
Jens Axboe498d3aa2007-04-26 12:54:48 +0200385/*
386 * The below is leftmost cache rbtree addon
387 */
Jens Axboe08717142008-01-28 11:38:15 +0100388static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
Jens Axboecc09e292007-04-26 12:53:50 +0200389{
390 if (!root->left)
391 root->left = rb_first(&root->rb);
392
Jens Axboe08717142008-01-28 11:38:15 +0100393 if (root->left)
394 return rb_entry(root->left, struct cfq_queue, rb_node);
395
396 return NULL;
Jens Axboecc09e292007-04-26 12:53:50 +0200397}
398
399static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
400{
401 if (root->left == n)
402 root->left = NULL;
403
404 rb_erase(n, &root->rb);
405 RB_CLEAR_NODE(n);
406}
407
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408/*
409 * would be nice to take fifo expire time into account as well
410 */
Jens Axboe5e705372006-07-13 12:39:25 +0200411static struct request *
412cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
413 struct request *last)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414{
Jens Axboe21183b02006-07-13 12:33:14 +0200415 struct rb_node *rbnext = rb_next(&last->rb_node);
416 struct rb_node *rbprev = rb_prev(&last->rb_node);
Jens Axboe5e705372006-07-13 12:39:25 +0200417 struct request *next = NULL, *prev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418
Jens Axboe21183b02006-07-13 12:33:14 +0200419 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420
421 if (rbprev)
Jens Axboe5e705372006-07-13 12:39:25 +0200422 prev = rb_entry_rq(rbprev);
Jens Axboe21183b02006-07-13 12:33:14 +0200423
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 if (rbnext)
Jens Axboe5e705372006-07-13 12:39:25 +0200425 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200426 else {
427 rbnext = rb_first(&cfqq->sort_list);
428 if (rbnext && rbnext != &last->rb_node)
Jens Axboe5e705372006-07-13 12:39:25 +0200429 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200430 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
Jens Axboe21183b02006-07-13 12:33:14 +0200432 return cfq_choose_req(cfqd, next, prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433}
434
Jens Axboed9e76202007-04-20 14:27:50 +0200435static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
436 struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437{
Jens Axboed9e76202007-04-20 14:27:50 +0200438 /*
439 * just an approximation, should be ok.
440 */
Jens Axboe67e6b492007-04-20 14:18:00 +0200441 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
442 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
Jens Axboed9e76202007-04-20 14:27:50 +0200443}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444
Jens Axboe498d3aa2007-04-26 12:54:48 +0200445/*
446 * The cfqd->service_tree holds all pending cfq_queue's that have
447 * requests waiting to be processed. It is sorted in the order that
448 * we will service the queues.
449 */
Jens Axboed9e76202007-04-20 14:27:50 +0200450static void cfq_service_tree_add(struct cfq_data *cfqd,
Jens Axboeedd75ff2007-04-19 12:03:34 +0200451 struct cfq_queue *cfqq, int add_front)
Jens Axboed9e76202007-04-20 14:27:50 +0200452{
Jens Axboe08717142008-01-28 11:38:15 +0100453 struct rb_node **p, *parent;
454 struct cfq_queue *__cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +0200455 unsigned long rb_key;
Jens Axboe498d3aa2007-04-26 12:54:48 +0200456 int left;
Jens Axboed9e76202007-04-20 14:27:50 +0200457
Jens Axboe08717142008-01-28 11:38:15 +0100458 if (cfq_class_idle(cfqq)) {
459 rb_key = CFQ_IDLE_DELAY;
460 parent = rb_last(&cfqd->service_tree.rb);
461 if (parent && parent != &cfqq->rb_node) {
462 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
463 rb_key += __cfqq->rb_key;
464 } else
465 rb_key += jiffies;
466 } else if (!add_front) {
Jens Axboeedd75ff2007-04-19 12:03:34 +0200467 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
468 rb_key += cfqq->slice_resid;
469 cfqq->slice_resid = 0;
470 } else
471 rb_key = 0;
Jens Axboed9e76202007-04-20 14:27:50 +0200472
473 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
Jens Axboe99f96282007-02-05 11:56:25 +0100474 /*
Jens Axboed9e76202007-04-20 14:27:50 +0200475 * same position, nothing more to do
Jens Axboe99f96282007-02-05 11:56:25 +0100476 */
Jens Axboed9e76202007-04-20 14:27:50 +0200477 if (rb_key == cfqq->rb_key)
478 return;
Jens Axboe53b03742006-07-28 09:48:51 +0200479
Jens Axboecc09e292007-04-26 12:53:50 +0200480 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
Jens Axboe22e2c502005-06-27 10:55:12 +0200481 }
Jens Axboed9e76202007-04-20 14:27:50 +0200482
Jens Axboe498d3aa2007-04-26 12:54:48 +0200483 left = 1;
Jens Axboe08717142008-01-28 11:38:15 +0100484 parent = NULL;
485 p = &cfqd->service_tree.rb.rb_node;
Jens Axboed9e76202007-04-20 14:27:50 +0200486 while (*p) {
Jens Axboe67060e32007-04-18 20:13:32 +0200487 struct rb_node **n;
Jens Axboecc09e292007-04-26 12:53:50 +0200488
Jens Axboed9e76202007-04-20 14:27:50 +0200489 parent = *p;
490 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
491
Jens Axboe0c534e02007-04-18 20:01:57 +0200492 /*
493 * sort RT queues first, we always want to give
Jens Axboe67060e32007-04-18 20:13:32 +0200494 * preference to them. IDLE queues goes to the back.
495 * after that, sort on the next service time.
Jens Axboe0c534e02007-04-18 20:01:57 +0200496 */
497 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
Jens Axboe67060e32007-04-18 20:13:32 +0200498 n = &(*p)->rb_left;
Jens Axboe0c534e02007-04-18 20:01:57 +0200499 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
Jens Axboe67060e32007-04-18 20:13:32 +0200500 n = &(*p)->rb_right;
501 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
502 n = &(*p)->rb_left;
503 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
504 n = &(*p)->rb_right;
Jens Axboe0c534e02007-04-18 20:01:57 +0200505 else if (rb_key < __cfqq->rb_key)
Jens Axboe67060e32007-04-18 20:13:32 +0200506 n = &(*p)->rb_left;
507 else
508 n = &(*p)->rb_right;
509
510 if (n == &(*p)->rb_right)
Jens Axboecc09e292007-04-26 12:53:50 +0200511 left = 0;
Jens Axboe67060e32007-04-18 20:13:32 +0200512
513 p = n;
Jens Axboed9e76202007-04-20 14:27:50 +0200514 }
515
Jens Axboecc09e292007-04-26 12:53:50 +0200516 if (left)
517 cfqd->service_tree.left = &cfqq->rb_node;
518
Jens Axboed9e76202007-04-20 14:27:50 +0200519 cfqq->rb_key = rb_key;
520 rb_link_node(&cfqq->rb_node, parent, p);
Jens Axboecc09e292007-04-26 12:53:50 +0200521 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522}
523
Jens Axboe498d3aa2007-04-26 12:54:48 +0200524/*
525 * Update cfqq's position in the service tree.
526 */
Jens Axboeedd75ff2007-04-19 12:03:34 +0200527static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +0200528{
Jens Axboe6d048f52007-04-25 12:44:27 +0200529 /*
530 * Resorting requires the cfqq to be on the RR list already.
531 */
Jens Axboe498d3aa2007-04-26 12:54:48 +0200532 if (cfq_cfqq_on_rr(cfqq))
Jens Axboeedd75ff2007-04-19 12:03:34 +0200533 cfq_service_tree_add(cfqd, cfqq, 0);
Jens Axboe6d048f52007-04-25 12:44:27 +0200534}
535
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536/*
537 * add to busy list of queues for service, trying to be fair in ordering
Jens Axboe22e2c502005-06-27 10:55:12 +0200538 * the pending list according to last request service
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 */
Jens Axboefebffd62008-01-28 13:19:43 +0100540static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
Jens Axboe3b181522005-06-27 10:56:24 +0200542 BUG_ON(cfq_cfqq_on_rr(cfqq));
543 cfq_mark_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 cfqd->busy_queues++;
545
Jens Axboeedd75ff2007-04-19 12:03:34 +0200546 cfq_resort_rr_list(cfqd, cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547}
548
Jens Axboe498d3aa2007-04-26 12:54:48 +0200549/*
550 * Called when the cfqq no longer has requests pending, remove it from
551 * the service tree.
552 */
Jens Axboefebffd62008-01-28 13:19:43 +0100553static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554{
Jens Axboe3b181522005-06-27 10:56:24 +0200555 BUG_ON(!cfq_cfqq_on_rr(cfqq));
556 cfq_clear_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
Jens Axboecc09e292007-04-26 12:53:50 +0200558 if (!RB_EMPTY_NODE(&cfqq->rb_node))
559 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
Jens Axboed9e76202007-04-20 14:27:50 +0200560
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 BUG_ON(!cfqd->busy_queues);
562 cfqd->busy_queues--;
563}
564
565/*
566 * rb tree support functions
567 */
Jens Axboefebffd62008-01-28 13:19:43 +0100568static void cfq_del_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569{
Jens Axboe5e705372006-07-13 12:39:25 +0200570 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +0200571 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe5e705372006-07-13 12:39:25 +0200572 const int sync = rq_is_sync(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573
Jens Axboeb4878f22005-10-20 16:42:29 +0200574 BUG_ON(!cfqq->queued[sync]);
575 cfqq->queued[sync]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576
Jens Axboe5e705372006-07-13 12:39:25 +0200577 elv_rb_del(&cfqq->sort_list, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
Jens Axboedd67d052006-06-21 09:36:18 +0200579 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboeb4878f22005-10-20 16:42:29 +0200580 cfq_del_cfqq_rr(cfqd, cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581}
582
Jens Axboe5e705372006-07-13 12:39:25 +0200583static void cfq_add_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584{
Jens Axboe5e705372006-07-13 12:39:25 +0200585 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe21183b02006-07-13 12:33:14 +0200587 struct request *__alias;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588
Jens Axboe5380a102006-07-13 12:37:56 +0200589 cfqq->queued[rq_is_sync(rq)]++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
591 /*
592 * looks a little odd, but the first insert might return an alias.
593 * if that happens, put the alias on the dispatch list
594 */
Jens Axboe21183b02006-07-13 12:33:14 +0200595 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
Jens Axboe5e705372006-07-13 12:39:25 +0200596 cfq_dispatch_insert(cfqd->queue, __alias);
Jens Axboe5fccbf62006-10-31 14:21:55 +0100597
598 if (!cfq_cfqq_on_rr(cfqq))
599 cfq_add_cfqq_rr(cfqd, cfqq);
Jens Axboe5044eed2007-04-25 11:53:48 +0200600
601 /*
602 * check if this request is a better next-serve candidate
603 */
604 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
605 BUG_ON(!cfqq->next_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606}
607
Jens Axboefebffd62008-01-28 13:19:43 +0100608static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609{
Jens Axboe5380a102006-07-13 12:37:56 +0200610 elv_rb_del(&cfqq->sort_list, rq);
611 cfqq->queued[rq_is_sync(rq)]--;
Jens Axboe5e705372006-07-13 12:39:25 +0200612 cfq_add_rq_rb(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613}
614
Jens Axboe206dc692006-03-28 13:03:44 +0200615static struct request *
616cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617{
Jens Axboe206dc692006-03-28 13:03:44 +0200618 struct task_struct *tsk = current;
Vasily Tarasov91fac312007-04-25 12:29:51 +0200619 struct cfq_io_context *cic;
Jens Axboe206dc692006-03-28 13:03:44 +0200620 struct cfq_queue *cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621
Jens Axboe4ac845a2008-01-24 08:44:49 +0100622 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200623 if (!cic)
624 return NULL;
625
626 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboe89850f72006-07-22 16:48:31 +0200627 if (cfqq) {
628 sector_t sector = bio->bi_sector + bio_sectors(bio);
629
Jens Axboe21183b02006-07-13 12:33:14 +0200630 return elv_rb_find(&cfqq->sort_list, sector);
Jens Axboe89850f72006-07-22 16:48:31 +0200631 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 return NULL;
634}
635
Jens Axboe165125e2007-07-24 09:28:11 +0200636static void cfq_activate_request(struct request_queue *q, struct request *rq)
Jens Axboeb4878f22005-10-20 16:42:29 +0200637{
638 struct cfq_data *cfqd = q->elevator->elevator_data;
639
640 cfqd->rq_in_driver++;
Jens Axboe25776e32006-06-01 10:12:26 +0200641
642 /*
643 * If the depth is larger 1, it really could be queueing. But lets
644 * make the mark a little higher - idling could still be good for
645 * low queueing, and a low queueing number could also just indicate
646 * a SCSI mid layer like behaviour where limit+1 is often seen.
647 */
648 if (!cfqd->hw_tag && cfqd->rq_in_driver > 4)
649 cfqd->hw_tag = 1;
Jens Axboe6d048f52007-04-25 12:44:27 +0200650
651 cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors;
Jens Axboeb4878f22005-10-20 16:42:29 +0200652}
653
Jens Axboe165125e2007-07-24 09:28:11 +0200654static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655{
Jens Axboe22e2c502005-06-27 10:55:12 +0200656 struct cfq_data *cfqd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657
Jens Axboeb4878f22005-10-20 16:42:29 +0200658 WARN_ON(!cfqd->rq_in_driver);
659 cfqd->rq_in_driver--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660}
661
Jens Axboeb4878f22005-10-20 16:42:29 +0200662static void cfq_remove_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663{
Jens Axboe5e705372006-07-13 12:39:25 +0200664 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe21183b02006-07-13 12:33:14 +0200665
Jens Axboe5e705372006-07-13 12:39:25 +0200666 if (cfqq->next_rq == rq)
667 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668
Jens Axboeb4878f22005-10-20 16:42:29 +0200669 list_del_init(&rq->queuelist);
Jens Axboe5e705372006-07-13 12:39:25 +0200670 cfq_del_rq_rb(rq);
Jens Axboe374f84a2006-07-23 01:42:19 +0200671
672 if (rq_is_meta(rq)) {
673 WARN_ON(!cfqq->meta_pending);
674 cfqq->meta_pending--;
675 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676}
677
Jens Axboe165125e2007-07-24 09:28:11 +0200678static int cfq_merge(struct request_queue *q, struct request **req,
679 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680{
681 struct cfq_data *cfqd = q->elevator->elevator_data;
682 struct request *__rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683
Jens Axboe206dc692006-03-28 13:03:44 +0200684 __rq = cfq_find_rq_fmerge(cfqd, bio);
Jens Axboe22e2c502005-06-27 10:55:12 +0200685 if (__rq && elv_rq_merge_ok(__rq, bio)) {
Jens Axboe98170642006-07-28 09:23:08 +0200686 *req = __rq;
687 return ELEVATOR_FRONT_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 }
689
690 return ELEVATOR_NO_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691}
692
Jens Axboe165125e2007-07-24 09:28:11 +0200693static void cfq_merged_request(struct request_queue *q, struct request *req,
Jens Axboe21183b02006-07-13 12:33:14 +0200694 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695{
Jens Axboe21183b02006-07-13 12:33:14 +0200696 if (type == ELEVATOR_FRONT_MERGE) {
Jens Axboe5e705372006-07-13 12:39:25 +0200697 struct cfq_queue *cfqq = RQ_CFQQ(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698
Jens Axboe5e705372006-07-13 12:39:25 +0200699 cfq_reposition_rq_rb(cfqq, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701}
702
703static void
Jens Axboe165125e2007-07-24 09:28:11 +0200704cfq_merged_requests(struct request_queue *q, struct request *rq,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 struct request *next)
706{
Jens Axboe22e2c502005-06-27 10:55:12 +0200707 /*
708 * reposition in fifo if next is older than rq
709 */
710 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
711 time_before(next->start_time, rq->start_time))
712 list_move(&rq->queuelist, &next->queuelist);
713
Jens Axboeb4878f22005-10-20 16:42:29 +0200714 cfq_remove_request(next);
Jens Axboe22e2c502005-06-27 10:55:12 +0200715}
716
Jens Axboe165125e2007-07-24 09:28:11 +0200717static int cfq_allow_merge(struct request_queue *q, struct request *rq,
Jens Axboeda775262006-12-20 11:04:12 +0100718 struct bio *bio)
719{
720 struct cfq_data *cfqd = q->elevator->elevator_data;
Vasily Tarasov91fac312007-04-25 12:29:51 +0200721 struct cfq_io_context *cic;
Jens Axboeda775262006-12-20 11:04:12 +0100722 struct cfq_queue *cfqq;
Jens Axboeda775262006-12-20 11:04:12 +0100723
724 /*
Jens Axboeec8acb62007-01-02 18:32:11 +0100725 * Disallow merge of a sync bio into an async request.
Jens Axboeda775262006-12-20 11:04:12 +0100726 */
Vasily Tarasov91fac312007-04-25 12:29:51 +0200727 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
Jens Axboeda775262006-12-20 11:04:12 +0100728 return 0;
729
730 /*
Jens Axboe719d3402006-12-22 09:38:53 +0100731 * Lookup the cfqq that this bio will be queued with. Allow
732 * merge only if rq is queued there.
Jens Axboeda775262006-12-20 11:04:12 +0100733 */
Jens Axboe4ac845a2008-01-24 08:44:49 +0100734 cic = cfq_cic_lookup(cfqd, current->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200735 if (!cic)
736 return 0;
Jens Axboe719d3402006-12-22 09:38:53 +0100737
Vasily Tarasov91fac312007-04-25 12:29:51 +0200738 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboe719d3402006-12-22 09:38:53 +0100739 if (cfqq == RQ_CFQQ(rq))
740 return 1;
Jens Axboeda775262006-12-20 11:04:12 +0100741
Jens Axboeec8acb62007-01-02 18:32:11 +0100742 return 0;
Jens Axboeda775262006-12-20 11:04:12 +0100743}
744
Jens Axboefebffd62008-01-28 13:19:43 +0100745static void __cfq_set_active_queue(struct cfq_data *cfqd,
746 struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +0200747{
748 if (cfqq) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200749 cfqq->slice_end = 0;
Jens Axboe3b181522005-06-27 10:56:24 +0200750 cfq_clear_cfqq_must_alloc_slice(cfqq);
751 cfq_clear_cfqq_fifo_expire(cfqq);
Jens Axboe44f7c162007-01-19 11:51:58 +1100752 cfq_mark_cfqq_slice_new(cfqq);
Jens Axboe1afba042007-04-17 12:47:55 +0200753 cfq_clear_cfqq_queue_new(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +0200754 }
755
756 cfqd->active_queue = cfqq;
757}
758
759/*
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100760 * current cfqq expired its slice (or was too idle), select new one
761 */
762static void
763__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboe6084cdd2007-04-23 08:25:00 +0200764 int timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100765{
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100766 if (cfq_cfqq_wait_request(cfqq))
767 del_timer(&cfqd->idle_slice_timer);
768
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100769 cfq_clear_cfqq_must_dispatch(cfqq);
770 cfq_clear_cfqq_wait_request(cfqq);
771
772 /*
Jens Axboe6084cdd2007-04-23 08:25:00 +0200773 * store what was left of this slice, if the queue idled/timed out
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100774 */
Jens Axboe3c6bd2f2007-01-19 12:06:33 +1100775 if (timed_out && !cfq_cfqq_slice_new(cfqq))
Jens Axboec5b680f2007-01-19 11:56:49 +1100776 cfqq->slice_resid = cfqq->slice_end - jiffies;
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100777
Jens Axboeedd75ff2007-04-19 12:03:34 +0200778 cfq_resort_rr_list(cfqd, cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100779
780 if (cfqq == cfqd->active_queue)
781 cfqd->active_queue = NULL;
782
783 if (cfqd->active_cic) {
784 put_io_context(cfqd->active_cic->ioc);
785 cfqd->active_cic = NULL;
786 }
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100787}
788
Jens Axboe6084cdd2007-04-23 08:25:00 +0200789static inline void cfq_slice_expired(struct cfq_data *cfqd, int timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100790{
791 struct cfq_queue *cfqq = cfqd->active_queue;
792
793 if (cfqq)
Jens Axboe6084cdd2007-04-23 08:25:00 +0200794 __cfq_slice_expired(cfqd, cfqq, timed_out);
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100795}
796
Jens Axboe498d3aa2007-04-26 12:54:48 +0200797/*
798 * Get next queue for service. Unless we have a queue preemption,
799 * we'll simply select the first cfqq in the service tree.
800 */
Jens Axboe6d048f52007-04-25 12:44:27 +0200801static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +0200802{
Jens Axboeedd75ff2007-04-19 12:03:34 +0200803 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
804 return NULL;
805
Jens Axboe08717142008-01-28 11:38:15 +0100806 return cfq_rb_first(&cfqd->service_tree);
Jens Axboe6d048f52007-04-25 12:44:27 +0200807}
808
Jens Axboe498d3aa2007-04-26 12:54:48 +0200809/*
810 * Get and set a new active queue for service.
811 */
Jens Axboe6d048f52007-04-25 12:44:27 +0200812static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd)
813{
814 struct cfq_queue *cfqq;
815
Jens Axboed9e76202007-04-20 14:27:50 +0200816 cfqq = cfq_get_next_queue(cfqd);
Jens Axboe22e2c502005-06-27 10:55:12 +0200817 __cfq_set_active_queue(cfqd, cfqq);
Jens Axboe3b181522005-06-27 10:56:24 +0200818 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +0200819}
820
Jens Axboed9e76202007-04-20 14:27:50 +0200821static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
822 struct request *rq)
823{
824 if (rq->sector >= cfqd->last_position)
825 return rq->sector - cfqd->last_position;
826 else
827 return cfqd->last_position - rq->sector;
828}
829
Jens Axboe6d048f52007-04-25 12:44:27 +0200830static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
831{
832 struct cfq_io_context *cic = cfqd->active_cic;
Jens Axboecaaa5f92006-06-16 11:23:00 +0200833
Jens Axboe6d048f52007-04-25 12:44:27 +0200834 if (!sample_valid(cic->seek_samples))
835 return 0;
836
837 return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean;
838}
839
Jens Axboed9e76202007-04-20 14:27:50 +0200840static int cfq_close_cooperator(struct cfq_data *cfq_data,
841 struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +0200842{
Jens Axboe6d048f52007-04-25 12:44:27 +0200843 /*
Jens Axboed9e76202007-04-20 14:27:50 +0200844 * We should notice if some of the queues are cooperating, eg
845 * working closely on the same area of the disk. In that case,
846 * we can group them together and don't waste time idling.
Jens Axboe6d048f52007-04-25 12:44:27 +0200847 */
Jens Axboed9e76202007-04-20 14:27:50 +0200848 return 0;
Jens Axboe6d048f52007-04-25 12:44:27 +0200849}
850
851#define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024))
852
853static void cfq_arm_slice_timer(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +0200854{
Jens Axboe17926692007-01-19 11:59:30 +1100855 struct cfq_queue *cfqq = cfqd->active_queue;
Jens Axboe206dc692006-03-28 13:03:44 +0200856 struct cfq_io_context *cic;
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100857 unsigned long sl;
858
Jens Axboedd67d052006-06-21 09:36:18 +0200859 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
Jens Axboe6d048f52007-04-25 12:44:27 +0200860 WARN_ON(cfq_cfqq_slice_new(cfqq));
Jens Axboe22e2c502005-06-27 10:55:12 +0200861
862 /*
863 * idle is disabled, either manually or by past process history
864 */
Jens Axboe6d048f52007-04-25 12:44:27 +0200865 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
866 return;
867
Jens Axboe22e2c502005-06-27 10:55:12 +0200868 /*
869 * task has exited, don't wait
870 */
Jens Axboe206dc692006-03-28 13:03:44 +0200871 cic = cfqd->active_cic;
Nikanth Karthikesan66dac982007-11-27 12:47:04 +0100872 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
Jens Axboe6d048f52007-04-25 12:44:27 +0200873 return;
874
875 /*
876 * See if this prio level has a good candidate
877 */
Jens Axboe1afba042007-04-17 12:47:55 +0200878 if (cfq_close_cooperator(cfqd, cfqq) &&
879 (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2))
Jens Axboe6d048f52007-04-25 12:44:27 +0200880 return;
Jens Axboe22e2c502005-06-27 10:55:12 +0200881
Jens Axboe3b181522005-06-27 10:56:24 +0200882 cfq_mark_cfqq_must_dispatch(cfqq);
883 cfq_mark_cfqq_wait_request(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +0200884
Jens Axboe206dc692006-03-28 13:03:44 +0200885 /*
886 * we don't want to idle for seeks, but we do want to allow
887 * fair distribution of slice time for a process doing back-to-back
888 * seeks. so allow a little bit of time for him to submit a new rq
889 */
Jens Axboe6d048f52007-04-25 12:44:27 +0200890 sl = cfqd->cfq_slice_idle;
Jens Axboecaaa5f92006-06-16 11:23:00 +0200891 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
Jens Axboed9e76202007-04-20 14:27:50 +0200892 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
Jens Axboe206dc692006-03-28 13:03:44 +0200893
Jens Axboe7b14e3b2006-02-28 09:35:11 +0100894 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895}
896
Jens Axboe498d3aa2007-04-26 12:54:48 +0200897/*
898 * Move request from internal lists to the request queue dispatch list.
899 */
Jens Axboe165125e2007-07-24 09:28:11 +0200900static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901{
Jens Axboe3ed9a292007-04-23 08:33:33 +0200902 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +0200903 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +0200904
Jens Axboe5380a102006-07-13 12:37:56 +0200905 cfq_remove_request(rq);
Jens Axboe6d048f52007-04-25 12:44:27 +0200906 cfqq->dispatched++;
Jens Axboe5380a102006-07-13 12:37:56 +0200907 elv_dispatch_sort(q, rq);
Jens Axboe3ed9a292007-04-23 08:33:33 +0200908
909 if (cfq_cfqq_sync(cfqq))
910 cfqd->sync_flight++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911}
912
913/*
914 * return expired entry, or NULL to just start from scratch in rbtree
915 */
Jens Axboefebffd62008-01-28 13:19:43 +0100916static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917{
918 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe22e2c502005-06-27 10:55:12 +0200919 struct request *rq;
Jens Axboe89850f72006-07-22 16:48:31 +0200920 int fifo;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
Jens Axboe3b181522005-06-27 10:56:24 +0200922 if (cfq_cfqq_fifo_expire(cfqq))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 return NULL;
Jens Axboecb887412007-01-19 12:01:16 +1100924
925 cfq_mark_cfqq_fifo_expire(cfqq);
926
Jens Axboe89850f72006-07-22 16:48:31 +0200927 if (list_empty(&cfqq->fifo))
928 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929
Jens Axboe6d048f52007-04-25 12:44:27 +0200930 fifo = cfq_cfqq_sync(cfqq);
Jens Axboe89850f72006-07-22 16:48:31 +0200931 rq = rq_entry_fifo(cfqq->fifo.next);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932
Jens Axboe6d048f52007-04-25 12:44:27 +0200933 if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
934 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
Jens Axboe6d048f52007-04-25 12:44:27 +0200936 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937}
938
Jens Axboe22e2c502005-06-27 10:55:12 +0200939static inline int
940cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
941{
942 const int base_rq = cfqd->cfq_slice_async_rq;
943
944 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
945
946 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
947}
948
949/*
Jens Axboe498d3aa2007-04-26 12:54:48 +0200950 * Select a queue for service. If we have a current active queue,
951 * check whether to continue servicing it, or retrieve and set a new one.
Jens Axboe22e2c502005-06-27 10:55:12 +0200952 */
Tejun Heo1b5ed5e12005-11-10 08:49:19 +0100953static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +0200954{
Jens Axboe22e2c502005-06-27 10:55:12 +0200955 struct cfq_queue *cfqq;
956
957 cfqq = cfqd->active_queue;
958 if (!cfqq)
959 goto new_queue;
960
961 /*
Jens Axboe6d048f52007-04-25 12:44:27 +0200962 * The active queue has run out of time, expire it and select new.
Jens Axboe22e2c502005-06-27 10:55:12 +0200963 */
Jens Axboe6d048f52007-04-25 12:44:27 +0200964 if (cfq_slice_used(cfqq))
Jens Axboe3b181522005-06-27 10:56:24 +0200965 goto expire;
Jens Axboe22e2c502005-06-27 10:55:12 +0200966
967 /*
Jens Axboe6d048f52007-04-25 12:44:27 +0200968 * The active queue has requests and isn't expired, allow it to
969 * dispatch.
Jens Axboe22e2c502005-06-27 10:55:12 +0200970 */
Jens Axboedd67d052006-06-21 09:36:18 +0200971 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +0200972 goto keep_queue;
Jens Axboe6d048f52007-04-25 12:44:27 +0200973
974 /*
975 * No requests pending. If the active queue still has requests in
976 * flight or is idling for a new request, allow either of these
977 * conditions to happen (or time out) before selecting a new queue.
978 */
Jens Axboecc197472007-04-20 20:45:39 +0200979 if (timer_pending(&cfqd->idle_slice_timer) ||
980 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
Jens Axboecaaa5f92006-06-16 11:23:00 +0200981 cfqq = NULL;
982 goto keep_queue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200983 }
984
Jens Axboe3b181522005-06-27 10:56:24 +0200985expire:
Jens Axboe6084cdd2007-04-23 08:25:00 +0200986 cfq_slice_expired(cfqd, 0);
Jens Axboe3b181522005-06-27 10:56:24 +0200987new_queue:
988 cfqq = cfq_set_active_queue(cfqd);
Jens Axboe22e2c502005-06-27 10:55:12 +0200989keep_queue:
Jens Axboe3b181522005-06-27 10:56:24 +0200990 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +0200991}
992
Jens Axboe498d3aa2007-04-26 12:54:48 +0200993/*
994 * Dispatch some requests from cfqq, moving them to the request queue
995 * dispatch list.
996 */
Jens Axboe22e2c502005-06-27 10:55:12 +0200997static int
998__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
999 int max_dispatch)
1000{
1001 int dispatched = 0;
1002
Jens Axboedd67d052006-06-21 09:36:18 +02001003 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
Jens Axboe22e2c502005-06-27 10:55:12 +02001004
1005 do {
Jens Axboe5e705372006-07-13 12:39:25 +02001006 struct request *rq;
Jens Axboe22e2c502005-06-27 10:55:12 +02001007
1008 /*
1009 * follow expired path, else get first next available
1010 */
Jens Axboefe094d92008-01-31 13:08:54 +01001011 rq = cfq_check_fifo(cfqq);
1012 if (rq == NULL)
Jens Axboe5e705372006-07-13 12:39:25 +02001013 rq = cfqq->next_rq;
Jens Axboe22e2c502005-06-27 10:55:12 +02001014
1015 /*
1016 * finally, insert request into driver dispatch list
1017 */
Jens Axboe5e705372006-07-13 12:39:25 +02001018 cfq_dispatch_insert(cfqd->queue, rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001019
Jens Axboe22e2c502005-06-27 10:55:12 +02001020 dispatched++;
1021
1022 if (!cfqd->active_cic) {
Jens Axboe5e705372006-07-13 12:39:25 +02001023 atomic_inc(&RQ_CIC(rq)->ioc->refcount);
1024 cfqd->active_cic = RQ_CIC(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001025 }
1026
Jens Axboedd67d052006-06-21 09:36:18 +02001027 if (RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +02001028 break;
1029
1030 } while (dispatched < max_dispatch);
1031
1032 /*
Jens Axboe22e2c502005-06-27 10:55:12 +02001033 * expire an async queue immediately if it has used up its slice. idle
1034 * queue always expire after 1 dispatch round.
1035 */
Jens Axboea9938002007-04-20 08:55:52 +02001036 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
Jens Axboe20e493a2007-04-23 08:26:36 +02001037 dispatched >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
Jens Axboea9938002007-04-20 08:55:52 +02001038 cfq_class_idle(cfqq))) {
Jens Axboe44f7c162007-01-19 11:51:58 +11001039 cfqq->slice_end = jiffies + 1;
Jens Axboe6084cdd2007-04-23 08:25:00 +02001040 cfq_slice_expired(cfqd, 0);
Jens Axboe44f7c162007-01-19 11:51:58 +11001041 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001042
1043 return dispatched;
1044}
1045
Jens Axboefebffd62008-01-28 13:19:43 +01001046static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
Jens Axboed9e76202007-04-20 14:27:50 +02001047{
1048 int dispatched = 0;
1049
1050 while (cfqq->next_rq) {
1051 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1052 dispatched++;
1053 }
1054
1055 BUG_ON(!list_empty(&cfqq->fifo));
1056 return dispatched;
1057}
1058
Jens Axboe498d3aa2007-04-26 12:54:48 +02001059/*
1060 * Drain our current requests. Used for barriers and when switching
1061 * io schedulers on-the-fly.
1062 */
Jens Axboed9e76202007-04-20 14:27:50 +02001063static int cfq_forced_dispatch(struct cfq_data *cfqd)
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01001064{
Jens Axboe08717142008-01-28 11:38:15 +01001065 struct cfq_queue *cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +02001066 int dispatched = 0;
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01001067
Jens Axboe08717142008-01-28 11:38:15 +01001068 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
Jens Axboed9e76202007-04-20 14:27:50 +02001069 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01001070
Jens Axboe6084cdd2007-04-23 08:25:00 +02001071 cfq_slice_expired(cfqd, 0);
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01001072
1073 BUG_ON(cfqd->busy_queues);
1074
1075 return dispatched;
1076}
1077
Jens Axboe165125e2007-07-24 09:28:11 +02001078static int cfq_dispatch_requests(struct request_queue *q, int force)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079{
1080 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe6d048f52007-04-25 12:44:27 +02001081 struct cfq_queue *cfqq;
Jens Axboecaaa5f92006-06-16 11:23:00 +02001082 int dispatched;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083
Jens Axboe22e2c502005-06-27 10:55:12 +02001084 if (!cfqd->busy_queues)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 return 0;
1086
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01001087 if (unlikely(force))
1088 return cfq_forced_dispatch(cfqd);
1089
Jens Axboecaaa5f92006-06-16 11:23:00 +02001090 dispatched = 0;
Jens Axboecaaa5f92006-06-16 11:23:00 +02001091 while ((cfqq = cfq_select_queue(cfqd)) != NULL) {
Jens Axboeb4878f22005-10-20 16:42:29 +02001092 int max_dispatch;
1093
Jens Axboe3ed9a292007-04-23 08:33:33 +02001094 max_dispatch = cfqd->cfq_quantum;
1095 if (cfq_class_idle(cfqq))
1096 max_dispatch = 1;
1097
1098 if (cfqq->dispatched >= max_dispatch) {
1099 if (cfqd->busy_queues > 1)
Jens Axboe6d048f52007-04-25 12:44:27 +02001100 break;
Jens Axboe3ed9a292007-04-23 08:33:33 +02001101 if (cfqq->dispatched >= 4 * max_dispatch)
Jens Axboea9938002007-04-20 08:55:52 +02001102 break;
1103 }
Jens Axboe9ede2092007-01-19 12:11:44 +11001104
Jens Axboe3ed9a292007-04-23 08:33:33 +02001105 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
1106 break;
1107
Jens Axboe3b181522005-06-27 10:56:24 +02001108 cfq_clear_cfqq_must_dispatch(cfqq);
1109 cfq_clear_cfqq_wait_request(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001110 del_timer(&cfqd->idle_slice_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111
Jens Axboecaaa5f92006-06-16 11:23:00 +02001112 dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 }
1114
Jens Axboecaaa5f92006-06-16 11:23:00 +02001115 return dispatched;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116}
1117
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118/*
Jens Axboe5e705372006-07-13 12:39:25 +02001119 * task holds one reference to the queue, dropped when task exits. each rq
1120 * in-flight on this queue also holds a reference, dropped when rq is freed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 *
1122 * queue lock must be held here.
1123 */
1124static void cfq_put_queue(struct cfq_queue *cfqq)
1125{
Jens Axboe22e2c502005-06-27 10:55:12 +02001126 struct cfq_data *cfqd = cfqq->cfqd;
1127
1128 BUG_ON(atomic_read(&cfqq->ref) <= 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129
1130 if (!atomic_dec_and_test(&cfqq->ref))
1131 return;
1132
1133 BUG_ON(rb_first(&cfqq->sort_list));
Jens Axboe22e2c502005-06-27 10:55:12 +02001134 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
Jens Axboe3b181522005-06-27 10:56:24 +02001135 BUG_ON(cfq_cfqq_on_rr(cfqq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136
Jens Axboe28f95cbc2007-01-19 12:09:53 +11001137 if (unlikely(cfqd->active_queue == cfqq)) {
Jens Axboe6084cdd2007-04-23 08:25:00 +02001138 __cfq_slice_expired(cfqd, cfqq, 0);
Jens Axboe28f95cbc2007-01-19 12:09:53 +11001139 cfq_schedule_dispatch(cfqd);
1140 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001141
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 kmem_cache_free(cfq_pool, cfqq);
1143}
1144
Jens Axboe4ac845a2008-01-24 08:44:49 +01001145/*
1146 * Call func for each cic attached to this ioc. Returns number of cic's seen.
1147 */
1148#define CIC_GANG_NR 16
1149static unsigned int
1150call_for_each_cic(struct io_context *ioc,
1151 void (*func)(struct io_context *, struct cfq_io_context *))
1152{
1153 struct cfq_io_context *cics[CIC_GANG_NR];
1154 unsigned long index = 0;
1155 unsigned int called = 0;
1156 int nr;
1157
1158 rcu_read_lock();
1159
1160 do {
1161 int i;
1162
1163 /*
1164 * Perhaps there's a better way - this just gang lookups from
1165 * 0 to the end, restarting after each CIC_GANG_NR from the
1166 * last key + 1.
1167 */
1168 nr = radix_tree_gang_lookup(&ioc->radix_root, (void **) cics,
1169 index, CIC_GANG_NR);
1170 if (!nr)
1171 break;
1172
1173 called += nr;
1174 index = 1 + (unsigned long) cics[nr - 1]->key;
1175
1176 for (i = 0; i < nr; i++)
1177 func(ioc, cics[i]);
1178 } while (nr == CIC_GANG_NR);
1179
1180 rcu_read_unlock();
1181
1182 return called;
1183}
1184
1185static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1186{
1187 unsigned long flags;
1188
1189 BUG_ON(!cic->dead_key);
1190
1191 spin_lock_irqsave(&ioc->lock, flags);
1192 radix_tree_delete(&ioc->radix_root, cic->dead_key);
1193 spin_unlock_irqrestore(&ioc->lock, flags);
1194
1195 kmem_cache_free(cfq_ioc_pool, cic);
1196}
1197
Jens Axboee2d74ac2006-03-28 08:59:01 +02001198static void cfq_free_io_context(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199{
Jens Axboe4ac845a2008-01-24 08:44:49 +01001200 int freed;
Jens Axboe22e2c502005-06-27 10:55:12 +02001201
Jens Axboe4ac845a2008-01-24 08:44:49 +01001202 /*
1203 * ioc->refcount is zero here, so no more cic's are allowed to be
1204 * linked into this ioc. So it should be ok to iterate over the known
1205 * list, we will see all cic's since no new ones are added.
1206 */
1207 freed = call_for_each_cic(ioc, cic_free_func);
Jens Axboe22e2c502005-06-27 10:55:12 +02001208
Jens Axboe4050cf12006-07-19 05:07:12 +02001209 elv_ioc_count_mod(ioc_count, -freed);
1210
1211 if (ioc_gone && !elv_ioc_count_read(ioc_count))
Al Viro334e94d2006-03-18 15:05:53 -05001212 complete(ioc_gone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213}
1214
Jens Axboe89850f72006-07-22 16:48:31 +02001215static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1216{
Jens Axboe28f95cbc2007-01-19 12:09:53 +11001217 if (unlikely(cfqq == cfqd->active_queue)) {
Jens Axboe6084cdd2007-04-23 08:25:00 +02001218 __cfq_slice_expired(cfqd, cfqq, 0);
Jens Axboe28f95cbc2007-01-19 12:09:53 +11001219 cfq_schedule_dispatch(cfqd);
1220 }
Jens Axboe89850f72006-07-22 16:48:31 +02001221
1222 cfq_put_queue(cfqq);
1223}
1224
1225static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1226 struct cfq_io_context *cic)
1227{
Jens Axboefc463792006-08-29 09:05:44 +02001228 list_del_init(&cic->queue_list);
Jens Axboe4ac845a2008-01-24 08:44:49 +01001229
1230 /*
1231 * Make sure key == NULL is seen for dead queues
1232 */
Jens Axboefc463792006-08-29 09:05:44 +02001233 smp_wmb();
Jens Axboe4ac845a2008-01-24 08:44:49 +01001234 cic->dead_key = (unsigned long) cic->key;
Jens Axboefc463792006-08-29 09:05:44 +02001235 cic->key = NULL;
1236
Jens Axboe89850f72006-07-22 16:48:31 +02001237 if (cic->cfqq[ASYNC]) {
1238 cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]);
1239 cic->cfqq[ASYNC] = NULL;
1240 }
1241
1242 if (cic->cfqq[SYNC]) {
1243 cfq_exit_cfqq(cfqd, cic->cfqq[SYNC]);
1244 cic->cfqq[SYNC] = NULL;
1245 }
Jens Axboe89850f72006-07-22 16:48:31 +02001246}
1247
Jens Axboe4ac845a2008-01-24 08:44:49 +01001248static void cfq_exit_single_io_context(struct io_context *ioc,
1249 struct cfq_io_context *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02001250{
Al Viro478a82b2006-03-18 13:25:24 -05001251 struct cfq_data *cfqd = cic->key;
Jens Axboe22e2c502005-06-27 10:55:12 +02001252
Jens Axboe89850f72006-07-22 16:48:31 +02001253 if (cfqd) {
Jens Axboe165125e2007-07-24 09:28:11 +02001254 struct request_queue *q = cfqd->queue;
Jens Axboe4ac845a2008-01-24 08:44:49 +01001255 unsigned long flags;
Jens Axboe22e2c502005-06-27 10:55:12 +02001256
Jens Axboe4ac845a2008-01-24 08:44:49 +01001257 spin_lock_irqsave(q->queue_lock, flags);
Jens Axboe89850f72006-07-22 16:48:31 +02001258 __cfq_exit_single_io_context(cfqd, cic);
Jens Axboe4ac845a2008-01-24 08:44:49 +01001259 spin_unlock_irqrestore(q->queue_lock, flags);
Al Viro12a05732006-03-18 13:38:01 -05001260 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001261}
1262
Jens Axboe498d3aa2007-04-26 12:54:48 +02001263/*
1264 * The process that ioc belongs to has exited, we need to clean up
1265 * and put the internal structures we have that belongs to that process.
1266 */
Jens Axboee2d74ac2006-03-28 08:59:01 +02001267static void cfq_exit_io_context(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268{
Jens Axboe4ac845a2008-01-24 08:44:49 +01001269 rcu_assign_pointer(ioc->ioc_data, NULL);
1270 call_for_each_cic(ioc, cfq_exit_single_io_context);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271}
1272
Jens Axboe22e2c502005-06-27 10:55:12 +02001273static struct cfq_io_context *
Al Viro8267e262005-10-21 03:20:53 -04001274cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275{
Jens Axboeb5deef92006-07-19 23:39:40 +02001276 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277
Christoph Lameter94f60302007-07-17 04:03:29 -07001278 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1279 cfqd->queue->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280 if (cic) {
Jens Axboe22e2c502005-06-27 10:55:12 +02001281 cic->last_end_request = jiffies;
Jens Axboe553698f2006-06-14 19:11:57 +02001282 INIT_LIST_HEAD(&cic->queue_list);
Jens Axboe22e2c502005-06-27 10:55:12 +02001283 cic->dtor = cfq_free_io_context;
1284 cic->exit = cfq_exit_io_context;
Jens Axboe4050cf12006-07-19 05:07:12 +02001285 elv_ioc_count_inc(ioc_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 }
1287
1288 return cic;
1289}
1290
Jens Axboefd0928d2008-01-24 08:52:45 +01001291static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
Jens Axboe22e2c502005-06-27 10:55:12 +02001292{
1293 struct task_struct *tsk = current;
1294 int ioprio_class;
1295
Jens Axboe3b181522005-06-27 10:56:24 +02001296 if (!cfq_cfqq_prio_changed(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02001297 return;
1298
Jens Axboefd0928d2008-01-24 08:52:45 +01001299 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +02001300 switch (ioprio_class) {
Jens Axboefe094d92008-01-31 13:08:54 +01001301 default:
1302 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1303 case IOPRIO_CLASS_NONE:
1304 /*
1305 * no prio set, place us in the middle of the BE classes
1306 */
1307 cfqq->ioprio = task_nice_ioprio(tsk);
1308 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1309 break;
1310 case IOPRIO_CLASS_RT:
1311 cfqq->ioprio = task_ioprio(ioc);
1312 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1313 break;
1314 case IOPRIO_CLASS_BE:
1315 cfqq->ioprio = task_ioprio(ioc);
1316 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1317 break;
1318 case IOPRIO_CLASS_IDLE:
1319 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1320 cfqq->ioprio = 7;
1321 cfq_clear_cfqq_idle_window(cfqq);
1322 break;
Jens Axboe22e2c502005-06-27 10:55:12 +02001323 }
1324
1325 /*
1326 * keep track of original prio settings in case we have to temporarily
1327 * elevate the priority of this queue
1328 */
1329 cfqq->org_ioprio = cfqq->ioprio;
1330 cfqq->org_ioprio_class = cfqq->ioprio_class;
Jens Axboe3b181522005-06-27 10:56:24 +02001331 cfq_clear_cfqq_prio_changed(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001332}
1333
Jens Axboefebffd62008-01-28 13:19:43 +01001334static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02001335{
Al Viro478a82b2006-03-18 13:25:24 -05001336 struct cfq_data *cfqd = cic->key;
1337 struct cfq_queue *cfqq;
Jens Axboec1b707d2006-10-30 19:54:23 +01001338 unsigned long flags;
Jens Axboe35e60772006-06-14 09:10:45 +02001339
Jens Axboecaaa5f92006-06-16 11:23:00 +02001340 if (unlikely(!cfqd))
1341 return;
1342
Jens Axboec1b707d2006-10-30 19:54:23 +01001343 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
Jens Axboecaaa5f92006-06-16 11:23:00 +02001344
1345 cfqq = cic->cfqq[ASYNC];
1346 if (cfqq) {
1347 struct cfq_queue *new_cfqq;
Jens Axboefd0928d2008-01-24 08:52:45 +01001348 new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc, GFP_ATOMIC);
Jens Axboecaaa5f92006-06-16 11:23:00 +02001349 if (new_cfqq) {
1350 cic->cfqq[ASYNC] = new_cfqq;
1351 cfq_put_queue(cfqq);
1352 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001353 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02001354
1355 cfqq = cic->cfqq[SYNC];
1356 if (cfqq)
1357 cfq_mark_cfqq_prio_changed(cfqq);
1358
Jens Axboec1b707d2006-10-30 19:54:23 +01001359 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
Jens Axboe22e2c502005-06-27 10:55:12 +02001360}
1361
Jens Axboefc463792006-08-29 09:05:44 +02001362static void cfq_ioc_set_ioprio(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363{
Jens Axboe4ac845a2008-01-24 08:44:49 +01001364 call_for_each_cic(ioc, changed_ioprio);
Jens Axboefc463792006-08-29 09:05:44 +02001365 ioc->ioprio_changed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366}
1367
1368static struct cfq_queue *
Jens Axboe15c31be2007-07-10 13:43:25 +02001369cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
Jens Axboefd0928d2008-01-24 08:52:45 +01001370 struct io_context *ioc, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 struct cfq_queue *cfqq, *new_cfqq = NULL;
Vasily Tarasov91fac312007-04-25 12:29:51 +02001373 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374
1375retry:
Jens Axboe4ac845a2008-01-24 08:44:49 +01001376 cic = cfq_cic_lookup(cfqd, ioc);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001377 /* cic always exists here */
1378 cfqq = cic_to_cfqq(cic, is_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
1380 if (!cfqq) {
1381 if (new_cfqq) {
1382 cfqq = new_cfqq;
1383 new_cfqq = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02001384 } else if (gfp_mask & __GFP_WAIT) {
Jens Axboe89850f72006-07-22 16:48:31 +02001385 /*
1386 * Inform the allocator of the fact that we will
1387 * just repeat this allocation if it fails, to allow
1388 * the allocator to do whatever it needs to attempt to
1389 * free memory.
1390 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 spin_unlock_irq(cfqd->queue->queue_lock);
Christoph Lameter94f60302007-07-17 04:03:29 -07001392 new_cfqq = kmem_cache_alloc_node(cfq_pool,
1393 gfp_mask | __GFP_NOFAIL | __GFP_ZERO,
1394 cfqd->queue->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 spin_lock_irq(cfqd->queue->queue_lock);
1396 goto retry;
Jens Axboe22e2c502005-06-27 10:55:12 +02001397 } else {
Christoph Lameter94f60302007-07-17 04:03:29 -07001398 cfqq = kmem_cache_alloc_node(cfq_pool,
1399 gfp_mask | __GFP_ZERO,
1400 cfqd->queue->node);
Jens Axboe22e2c502005-06-27 10:55:12 +02001401 if (!cfqq)
1402 goto out;
Kiyoshi Ueda db3b5842005-06-17 16:15:10 +02001403 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404
Jens Axboed9e76202007-04-20 14:27:50 +02001405 RB_CLEAR_NODE(&cfqq->rb_node);
Jens Axboe22e2c502005-06-27 10:55:12 +02001406 INIT_LIST_HEAD(&cfqq->fifo);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 atomic_set(&cfqq->ref, 0);
1409 cfqq->cfqd = cfqd;
Jens Axboec5b680f2007-01-19 11:56:49 +11001410
Jens Axboe3b181522005-06-27 10:56:24 +02001411 cfq_mark_cfqq_prio_changed(cfqq);
Jens Axboe53b03742006-07-28 09:48:51 +02001412 cfq_mark_cfqq_queue_new(cfqq);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001413
Jens Axboefd0928d2008-01-24 08:52:45 +01001414 cfq_init_prio_data(cfqq, ioc);
Jens Axboe08717142008-01-28 11:38:15 +01001415
1416 if (is_sync) {
1417 if (!cfq_class_idle(cfqq))
1418 cfq_mark_cfqq_idle_window(cfqq);
1419 cfq_mark_cfqq_sync(cfqq);
1420 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 }
1422
1423 if (new_cfqq)
1424 kmem_cache_free(cfq_pool, new_cfqq);
1425
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426out:
1427 WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
1428 return cfqq;
1429}
1430
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001431static struct cfq_queue **
1432cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1433{
Jens Axboefe094d92008-01-31 13:08:54 +01001434 switch (ioprio_class) {
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001435 case IOPRIO_CLASS_RT:
1436 return &cfqd->async_cfqq[0][ioprio];
1437 case IOPRIO_CLASS_BE:
1438 return &cfqd->async_cfqq[1][ioprio];
1439 case IOPRIO_CLASS_IDLE:
1440 return &cfqd->async_idle_cfqq;
1441 default:
1442 BUG();
1443 }
1444}
1445
Jens Axboe15c31be2007-07-10 13:43:25 +02001446static struct cfq_queue *
Jens Axboefd0928d2008-01-24 08:52:45 +01001447cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
Jens Axboe15c31be2007-07-10 13:43:25 +02001448 gfp_t gfp_mask)
1449{
Jens Axboefd0928d2008-01-24 08:52:45 +01001450 const int ioprio = task_ioprio(ioc);
1451 const int ioprio_class = task_ioprio_class(ioc);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001452 struct cfq_queue **async_cfqq = NULL;
Jens Axboe15c31be2007-07-10 13:43:25 +02001453 struct cfq_queue *cfqq = NULL;
1454
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001455 if (!is_sync) {
1456 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1457 cfqq = *async_cfqq;
1458 }
1459
Oleg Nesterov0a0836a2007-10-23 15:08:21 +02001460 if (!cfqq) {
Jens Axboefd0928d2008-01-24 08:52:45 +01001461 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
Oleg Nesterov0a0836a2007-10-23 15:08:21 +02001462 if (!cfqq)
1463 return NULL;
1464 }
Jens Axboe15c31be2007-07-10 13:43:25 +02001465
1466 /*
1467 * pin the queue now that it's allocated, scheduler exit will prune it
1468 */
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001469 if (!is_sync && !(*async_cfqq)) {
Jens Axboe15c31be2007-07-10 13:43:25 +02001470 atomic_inc(&cfqq->ref);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02001471 *async_cfqq = cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +02001472 }
1473
1474 atomic_inc(&cfqq->ref);
1475 return cfqq;
1476}
1477
Jens Axboe4ac845a2008-01-24 08:44:49 +01001478static void cfq_cic_free(struct cfq_io_context *cic)
1479{
1480 kmem_cache_free(cfq_ioc_pool, cic);
1481 elv_ioc_count_dec(ioc_count);
1482
1483 if (ioc_gone && !elv_ioc_count_read(ioc_count))
1484 complete(ioc_gone);
1485}
1486
Jens Axboe498d3aa2007-04-26 12:54:48 +02001487/*
1488 * We drop cfq io contexts lazily, so we may find a dead one.
1489 */
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02001490static void
Jens Axboe4ac845a2008-01-24 08:44:49 +01001491cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1492 struct cfq_io_context *cic)
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02001493{
Jens Axboe4ac845a2008-01-24 08:44:49 +01001494 unsigned long flags;
1495
Jens Axboefc463792006-08-29 09:05:44 +02001496 WARN_ON(!list_empty(&cic->queue_list));
Jens Axboe597bc482007-04-24 21:23:53 +02001497
Jens Axboe4ac845a2008-01-24 08:44:49 +01001498 spin_lock_irqsave(&ioc->lock, flags);
Jens Axboe597bc482007-04-24 21:23:53 +02001499
Jens Axboe4ac845a2008-01-24 08:44:49 +01001500 if (ioc->ioc_data == cic)
1501 rcu_assign_pointer(ioc->ioc_data, NULL);
1502
1503 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
1504 spin_unlock_irqrestore(&ioc->lock, flags);
1505
1506 cfq_cic_free(cic);
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02001507}
1508
Jens Axboee2d74ac2006-03-28 08:59:01 +02001509static struct cfq_io_context *
Jens Axboe4ac845a2008-01-24 08:44:49 +01001510cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
Jens Axboee2d74ac2006-03-28 08:59:01 +02001511{
Jens Axboee2d74ac2006-03-28 08:59:01 +02001512 struct cfq_io_context *cic;
Jens Axboe4ac845a2008-01-24 08:44:49 +01001513 void *k;
Jens Axboee2d74ac2006-03-28 08:59:01 +02001514
Vasily Tarasov91fac312007-04-25 12:29:51 +02001515 if (unlikely(!ioc))
1516 return NULL;
1517
Jens Axboe597bc482007-04-24 21:23:53 +02001518 /*
1519 * we maintain a last-hit cache, to avoid browsing over the tree
1520 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01001521 cic = rcu_dereference(ioc->ioc_data);
Jens Axboe597bc482007-04-24 21:23:53 +02001522 if (cic && cic->key == cfqd)
1523 return cic;
1524
Jens Axboe4ac845a2008-01-24 08:44:49 +01001525 do {
1526 rcu_read_lock();
1527 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1528 rcu_read_unlock();
1529 if (!cic)
1530 break;
OGAWA Hirofumibe3b0752006-04-18 19:18:31 +02001531 /* ->key must be copied to avoid race with cfq_exit_queue() */
1532 k = cic->key;
1533 if (unlikely(!k)) {
Jens Axboe4ac845a2008-01-24 08:44:49 +01001534 cfq_drop_dead_cic(cfqd, ioc, cic);
1535 continue;
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02001536 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02001537
Jens Axboe4ac845a2008-01-24 08:44:49 +01001538 rcu_assign_pointer(ioc->ioc_data, cic);
1539 break;
1540 } while (1);
Jens Axboee2d74ac2006-03-28 08:59:01 +02001541
Jens Axboe4ac845a2008-01-24 08:44:49 +01001542 return cic;
Jens Axboee2d74ac2006-03-28 08:59:01 +02001543}
1544
Jens Axboe4ac845a2008-01-24 08:44:49 +01001545/*
1546 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1547 * the process specific cfq io context when entered from the block layer.
1548 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1549 */
Jens Axboefebffd62008-01-28 13:19:43 +01001550static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1551 struct cfq_io_context *cic, gfp_t gfp_mask)
Jens Axboee2d74ac2006-03-28 08:59:01 +02001552{
Jens Axboe0261d682006-10-30 19:07:48 +01001553 unsigned long flags;
Jens Axboe4ac845a2008-01-24 08:44:49 +01001554 int ret;
Jens Axboee2d74ac2006-03-28 08:59:01 +02001555
Jens Axboe4ac845a2008-01-24 08:44:49 +01001556 ret = radix_tree_preload(gfp_mask);
1557 if (!ret) {
1558 cic->ioc = ioc;
1559 cic->key = cfqd;
Jens Axboee2d74ac2006-03-28 08:59:01 +02001560
Jens Axboe4ac845a2008-01-24 08:44:49 +01001561 spin_lock_irqsave(&ioc->lock, flags);
1562 ret = radix_tree_insert(&ioc->radix_root,
1563 (unsigned long) cfqd, cic);
1564 spin_unlock_irqrestore(&ioc->lock, flags);
1565
1566 radix_tree_preload_end();
1567
1568 if (!ret) {
1569 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1570 list_add(&cic->queue_list, &cfqd->cic_list);
1571 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02001572 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02001573 }
1574
Jens Axboe4ac845a2008-01-24 08:44:49 +01001575 if (ret)
1576 printk(KERN_ERR "cfq: cic link failed!\n");
Jens Axboefc463792006-08-29 09:05:44 +02001577
Jens Axboe4ac845a2008-01-24 08:44:49 +01001578 return ret;
Jens Axboee2d74ac2006-03-28 08:59:01 +02001579}
1580
Jens Axboe22e2c502005-06-27 10:55:12 +02001581/*
1582 * Setup general io context and cfq io context. There can be several cfq
1583 * io contexts per general io context, if this process is doing io to more
Jens Axboee2d74ac2006-03-28 08:59:01 +02001584 * than one device managed by cfq.
Jens Axboe22e2c502005-06-27 10:55:12 +02001585 */
1586static struct cfq_io_context *
Jens Axboee2d74ac2006-03-28 08:59:01 +02001587cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588{
Jens Axboe22e2c502005-06-27 10:55:12 +02001589 struct io_context *ioc = NULL;
1590 struct cfq_io_context *cic;
1591
1592 might_sleep_if(gfp_mask & __GFP_WAIT);
1593
Jens Axboeb5deef92006-07-19 23:39:40 +02001594 ioc = get_io_context(gfp_mask, cfqd->queue->node);
Jens Axboe22e2c502005-06-27 10:55:12 +02001595 if (!ioc)
1596 return NULL;
1597
Jens Axboe4ac845a2008-01-24 08:44:49 +01001598 cic = cfq_cic_lookup(cfqd, ioc);
Jens Axboee2d74ac2006-03-28 08:59:01 +02001599 if (cic)
1600 goto out;
Jens Axboe22e2c502005-06-27 10:55:12 +02001601
Jens Axboee2d74ac2006-03-28 08:59:01 +02001602 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1603 if (cic == NULL)
1604 goto err;
Jens Axboe22e2c502005-06-27 10:55:12 +02001605
Jens Axboe4ac845a2008-01-24 08:44:49 +01001606 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1607 goto err_free;
1608
Jens Axboe22e2c502005-06-27 10:55:12 +02001609out:
Jens Axboefc463792006-08-29 09:05:44 +02001610 smp_read_barrier_depends();
1611 if (unlikely(ioc->ioprio_changed))
1612 cfq_ioc_set_ioprio(ioc);
1613
Jens Axboe22e2c502005-06-27 10:55:12 +02001614 return cic;
Jens Axboe4ac845a2008-01-24 08:44:49 +01001615err_free:
1616 cfq_cic_free(cic);
Jens Axboe22e2c502005-06-27 10:55:12 +02001617err:
1618 put_io_context(ioc);
1619 return NULL;
1620}
1621
1622static void
1623cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1624{
Jens Axboeaaf12282007-01-19 11:30:16 +11001625 unsigned long elapsed = jiffies - cic->last_end_request;
1626 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
Jens Axboe22e2c502005-06-27 10:55:12 +02001627
1628 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1629 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1630 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1631}
1632
Jens Axboe206dc692006-03-28 13:03:44 +02001633static void
Jens Axboe6d048f52007-04-25 12:44:27 +02001634cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1635 struct request *rq)
Jens Axboe206dc692006-03-28 13:03:44 +02001636{
1637 sector_t sdist;
1638 u64 total;
1639
Jens Axboe5e705372006-07-13 12:39:25 +02001640 if (cic->last_request_pos < rq->sector)
1641 sdist = rq->sector - cic->last_request_pos;
Jens Axboe206dc692006-03-28 13:03:44 +02001642 else
Jens Axboe5e705372006-07-13 12:39:25 +02001643 sdist = cic->last_request_pos - rq->sector;
Jens Axboe206dc692006-03-28 13:03:44 +02001644
1645 /*
1646 * Don't allow the seek distance to get too large from the
1647 * odd fragment, pagein, etc
1648 */
1649 if (cic->seek_samples <= 60) /* second&third seek */
1650 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1651 else
1652 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1653
1654 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1655 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1656 total = cic->seek_total + (cic->seek_samples/2);
1657 do_div(total, cic->seek_samples);
1658 cic->seek_mean = (sector_t)total;
1659}
Jens Axboe22e2c502005-06-27 10:55:12 +02001660
1661/*
1662 * Disable idle window if the process thinks too long or seeks so much that
1663 * it doesn't matter
1664 */
1665static void
1666cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1667 struct cfq_io_context *cic)
1668{
Jens Axboe1be92f22007-04-19 14:32:26 +02001669 int enable_idle;
1670
Jens Axboe08717142008-01-28 11:38:15 +01001671 /*
1672 * Don't idle for async or idle io prio class
1673 */
1674 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
Jens Axboe1be92f22007-04-19 14:32:26 +02001675 return;
1676
1677 enable_idle = cfq_cfqq_idle_window(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001678
Nikanth Karthikesan66dac982007-11-27 12:47:04 +01001679 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
Jens Axboecaaa5f92006-06-16 11:23:00 +02001680 (cfqd->hw_tag && CIC_SEEKY(cic)))
Jens Axboe22e2c502005-06-27 10:55:12 +02001681 enable_idle = 0;
1682 else if (sample_valid(cic->ttime_samples)) {
1683 if (cic->ttime_mean > cfqd->cfq_slice_idle)
1684 enable_idle = 0;
1685 else
1686 enable_idle = 1;
1687 }
1688
Jens Axboe3b181522005-06-27 10:56:24 +02001689 if (enable_idle)
1690 cfq_mark_cfqq_idle_window(cfqq);
1691 else
1692 cfq_clear_cfqq_idle_window(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001693}
1694
Jens Axboe22e2c502005-06-27 10:55:12 +02001695/*
1696 * Check if new_cfqq should preempt the currently active queue. Return 0 for
1697 * no or if we aren't sure, a 1 will cause a preempt.
1698 */
1699static int
1700cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
Jens Axboe5e705372006-07-13 12:39:25 +02001701 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001702{
Jens Axboe6d048f52007-04-25 12:44:27 +02001703 struct cfq_queue *cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02001704
Jens Axboe6d048f52007-04-25 12:44:27 +02001705 cfqq = cfqd->active_queue;
1706 if (!cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001707 return 0;
1708
Jens Axboe6d048f52007-04-25 12:44:27 +02001709 if (cfq_slice_used(cfqq))
1710 return 1;
1711
1712 if (cfq_class_idle(new_cfqq))
Jens Axboecaaa5f92006-06-16 11:23:00 +02001713 return 0;
Jens Axboe22e2c502005-06-27 10:55:12 +02001714
1715 if (cfq_class_idle(cfqq))
1716 return 1;
Jens Axboe1e3335d2007-02-14 19:59:49 +01001717
Jens Axboe22e2c502005-06-27 10:55:12 +02001718 /*
Jens Axboe374f84a2006-07-23 01:42:19 +02001719 * if the new request is sync, but the currently running queue is
1720 * not, let the sync request have priority.
1721 */
Jens Axboe5e705372006-07-13 12:39:25 +02001722 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02001723 return 1;
Jens Axboe1e3335d2007-02-14 19:59:49 +01001724
Jens Axboe374f84a2006-07-23 01:42:19 +02001725 /*
1726 * So both queues are sync. Let the new request get disk time if
1727 * it's a metadata request and the current queue is doing regular IO.
1728 */
1729 if (rq_is_meta(rq) && !cfqq->meta_pending)
1730 return 1;
Jens Axboe22e2c502005-06-27 10:55:12 +02001731
Jens Axboe1e3335d2007-02-14 19:59:49 +01001732 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
1733 return 0;
1734
1735 /*
1736 * if this request is as-good as one we would expect from the
1737 * current cfqq, let it preempt
1738 */
Jens Axboe6d048f52007-04-25 12:44:27 +02001739 if (cfq_rq_close(cfqd, rq))
Jens Axboe1e3335d2007-02-14 19:59:49 +01001740 return 1;
1741
Jens Axboe22e2c502005-06-27 10:55:12 +02001742 return 0;
1743}
1744
1745/*
1746 * cfqq preempts the active queue. if we allowed preempt with no slice left,
1747 * let it have half of its nominal slice.
1748 */
1749static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1750{
Jens Axboe6084cdd2007-04-23 08:25:00 +02001751 cfq_slice_expired(cfqd, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02001752
Jens Axboebf572252006-07-19 20:29:12 +02001753 /*
1754 * Put the new queue at the front of the of the current list,
1755 * so we know that it will be selected next.
1756 */
1757 BUG_ON(!cfq_cfqq_on_rr(cfqq));
Jens Axboeedd75ff2007-04-19 12:03:34 +02001758
1759 cfq_service_tree_add(cfqd, cfqq, 1);
Jens Axboebf572252006-07-19 20:29:12 +02001760
Jens Axboe44f7c162007-01-19 11:51:58 +11001761 cfqq->slice_end = 0;
1762 cfq_mark_cfqq_slice_new(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001763}
1764
1765/*
Jens Axboe5e705372006-07-13 12:39:25 +02001766 * Called when a new fs request (rq) is added (to cfqq). Check if there's
Jens Axboe22e2c502005-06-27 10:55:12 +02001767 * something we should do about it
1768 */
1769static void
Jens Axboe5e705372006-07-13 12:39:25 +02001770cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1771 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001772{
Jens Axboe5e705372006-07-13 12:39:25 +02001773 struct cfq_io_context *cic = RQ_CIC(rq);
Jens Axboe12e9fdd2006-06-01 10:09:56 +02001774
Jens Axboe374f84a2006-07-23 01:42:19 +02001775 if (rq_is_meta(rq))
1776 cfqq->meta_pending++;
1777
Jens Axboe9c2c38a2005-08-24 14:57:54 +02001778 cfq_update_io_thinktime(cfqd, cic);
Jens Axboe6d048f52007-04-25 12:44:27 +02001779 cfq_update_io_seektime(cfqd, cic, rq);
Jens Axboe9c2c38a2005-08-24 14:57:54 +02001780 cfq_update_idle_window(cfqd, cfqq, cic);
1781
Jens Axboe5e705372006-07-13 12:39:25 +02001782 cic->last_request_pos = rq->sector + rq->nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02001783
1784 if (cfqq == cfqd->active_queue) {
1785 /*
1786 * if we are waiting for a request for this queue, let it rip
1787 * immediately and flag that we must not expire this queue
1788 * just now
1789 */
Jens Axboe3b181522005-06-27 10:56:24 +02001790 if (cfq_cfqq_wait_request(cfqq)) {
1791 cfq_mark_cfqq_must_dispatch(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001792 del_timer(&cfqd->idle_slice_timer);
Jens Axboedc72ef42006-07-20 14:54:05 +02001793 blk_start_queueing(cfqd->queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02001794 }
Jens Axboe5e705372006-07-13 12:39:25 +02001795 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
Jens Axboe22e2c502005-06-27 10:55:12 +02001796 /*
1797 * not the active queue - expire current slice if it is
1798 * idle and has expired it's mean thinktime or this new queue
1799 * has some old slice time left and is of higher priority
1800 */
1801 cfq_preempt_queue(cfqd, cfqq);
Jens Axboe3b181522005-06-27 10:56:24 +02001802 cfq_mark_cfqq_must_dispatch(cfqq);
Jens Axboedc72ef42006-07-20 14:54:05 +02001803 blk_start_queueing(cfqd->queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02001804 }
1805}
1806
Jens Axboe165125e2007-07-24 09:28:11 +02001807static void cfq_insert_request(struct request_queue *q, struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001808{
Jens Axboeb4878f22005-10-20 16:42:29 +02001809 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +02001810 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001811
Jens Axboefd0928d2008-01-24 08:52:45 +01001812 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
Jens Axboe5e705372006-07-13 12:39:25 +02001814 cfq_add_rq_rb(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815
Jens Axboe22e2c502005-06-27 10:55:12 +02001816 list_add_tail(&rq->queuelist, &cfqq->fifo);
1817
Jens Axboe5e705372006-07-13 12:39:25 +02001818 cfq_rq_enqueued(cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819}
1820
Jens Axboe165125e2007-07-24 09:28:11 +02001821static void cfq_completed_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822{
Jens Axboe5e705372006-07-13 12:39:25 +02001823 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02001824 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe5380a102006-07-13 12:37:56 +02001825 const int sync = rq_is_sync(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02001826 unsigned long now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827
Jens Axboeb4878f22005-10-20 16:42:29 +02001828 now = jiffies;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829
Jens Axboeb4878f22005-10-20 16:42:29 +02001830 WARN_ON(!cfqd->rq_in_driver);
Jens Axboe6d048f52007-04-25 12:44:27 +02001831 WARN_ON(!cfqq->dispatched);
Jens Axboeb4878f22005-10-20 16:42:29 +02001832 cfqd->rq_in_driver--;
Jens Axboe6d048f52007-04-25 12:44:27 +02001833 cfqq->dispatched--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834
Jens Axboe3ed9a292007-04-23 08:33:33 +02001835 if (cfq_cfqq_sync(cfqq))
1836 cfqd->sync_flight--;
1837
Jens Axboeb4878f22005-10-20 16:42:29 +02001838 if (!cfq_class_idle(cfqq))
1839 cfqd->last_end_request = now;
Jens Axboe3b181522005-06-27 10:56:24 +02001840
Jens Axboecaaa5f92006-06-16 11:23:00 +02001841 if (sync)
Jens Axboe5e705372006-07-13 12:39:25 +02001842 RQ_CIC(rq)->last_end_request = now;
Jens Axboecaaa5f92006-06-16 11:23:00 +02001843
1844 /*
1845 * If this is the active queue, check if it needs to be expired,
1846 * or if we want to idle in case it has no pending requests.
1847 */
1848 if (cfqd->active_queue == cfqq) {
Jens Axboe44f7c162007-01-19 11:51:58 +11001849 if (cfq_cfqq_slice_new(cfqq)) {
1850 cfq_set_prio_slice(cfqd, cfqq);
1851 cfq_clear_cfqq_slice_new(cfqq);
1852 }
Jens Axboe08717142008-01-28 11:38:15 +01001853 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
Jens Axboe6084cdd2007-04-23 08:25:00 +02001854 cfq_slice_expired(cfqd, 1);
Jens Axboe6d048f52007-04-25 12:44:27 +02001855 else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list))
1856 cfq_arm_slice_timer(cfqd);
Jens Axboecaaa5f92006-06-16 11:23:00 +02001857 }
Jens Axboe6d048f52007-04-25 12:44:27 +02001858
1859 if (!cfqd->rq_in_driver)
1860 cfq_schedule_dispatch(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861}
1862
Jens Axboe22e2c502005-06-27 10:55:12 +02001863/*
1864 * we temporarily boost lower priority queues if they are holding fs exclusive
1865 * resources. they are boosted to normal prio (CLASS_BE/4)
1866 */
1867static void cfq_prio_boost(struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868{
Jens Axboe22e2c502005-06-27 10:55:12 +02001869 if (has_fs_excl()) {
1870 /*
1871 * boost idle prio on transactions that would lock out other
1872 * users of the filesystem
1873 */
1874 if (cfq_class_idle(cfqq))
1875 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1876 if (cfqq->ioprio > IOPRIO_NORM)
1877 cfqq->ioprio = IOPRIO_NORM;
1878 } else {
1879 /*
1880 * check if we need to unboost the queue
1881 */
1882 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
1883 cfqq->ioprio_class = cfqq->org_ioprio_class;
1884 if (cfqq->ioprio != cfqq->org_ioprio)
1885 cfqq->ioprio = cfqq->org_ioprio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001887}
1888
Jens Axboe89850f72006-07-22 16:48:31 +02001889static inline int __cfq_may_queue(struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001890{
Jens Axboe3b181522005-06-27 10:56:24 +02001891 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) &&
Andrew Morton99f95e52005-06-27 20:14:05 -07001892 !cfq_cfqq_must_alloc_slice(cfqq)) {
Jens Axboe3b181522005-06-27 10:56:24 +02001893 cfq_mark_cfqq_must_alloc_slice(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001894 return ELV_MQUEUE_MUST;
Jens Axboe3b181522005-06-27 10:56:24 +02001895 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001896
1897 return ELV_MQUEUE_MAY;
Jens Axboe22e2c502005-06-27 10:55:12 +02001898}
1899
Jens Axboe165125e2007-07-24 09:28:11 +02001900static int cfq_may_queue(struct request_queue *q, int rw)
Jens Axboe22e2c502005-06-27 10:55:12 +02001901{
1902 struct cfq_data *cfqd = q->elevator->elevator_data;
1903 struct task_struct *tsk = current;
Vasily Tarasov91fac312007-04-25 12:29:51 +02001904 struct cfq_io_context *cic;
Jens Axboe22e2c502005-06-27 10:55:12 +02001905 struct cfq_queue *cfqq;
1906
1907 /*
1908 * don't force setup of a queue from here, as a call to may_queue
1909 * does not necessarily imply that a request actually will be queued.
1910 * so just lookup a possibly existing queue, or return 'may queue'
1911 * if that fails
1912 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01001913 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001914 if (!cic)
1915 return ELV_MQUEUE_MAY;
1916
1917 cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC);
Jens Axboe22e2c502005-06-27 10:55:12 +02001918 if (cfqq) {
Jens Axboefd0928d2008-01-24 08:52:45 +01001919 cfq_init_prio_data(cfqq, cic->ioc);
Jens Axboe22e2c502005-06-27 10:55:12 +02001920 cfq_prio_boost(cfqq);
1921
Jens Axboe89850f72006-07-22 16:48:31 +02001922 return __cfq_may_queue(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001923 }
1924
1925 return ELV_MQUEUE_MAY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926}
1927
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928/*
1929 * queue lock held here
1930 */
Jens Axboebb37b942006-12-01 10:42:33 +01001931static void cfq_put_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932{
Jens Axboe5e705372006-07-13 12:39:25 +02001933 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934
Jens Axboe5e705372006-07-13 12:39:25 +02001935 if (cfqq) {
Jens Axboe22e2c502005-06-27 10:55:12 +02001936 const int rw = rq_data_dir(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
Jens Axboe22e2c502005-06-27 10:55:12 +02001938 BUG_ON(!cfqq->allocated[rw]);
1939 cfqq->allocated[rw]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940
Jens Axboe5e705372006-07-13 12:39:25 +02001941 put_io_context(RQ_CIC(rq)->ioc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 rq->elevator_private = NULL;
Jens Axboe5e705372006-07-13 12:39:25 +02001944 rq->elevator_private2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 cfq_put_queue(cfqq);
1947 }
1948}
1949
1950/*
Jens Axboe22e2c502005-06-27 10:55:12 +02001951 * Allocate cfq data structures associated with this request.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 */
Jens Axboe22e2c502005-06-27 10:55:12 +02001953static int
Jens Axboe165125e2007-07-24 09:28:11 +02001954cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955{
1956 struct cfq_data *cfqd = q->elevator->elevator_data;
1957 struct cfq_io_context *cic;
1958 const int rw = rq_data_dir(rq);
Jens Axboe7749a8d2006-12-13 13:02:26 +01001959 const int is_sync = rq_is_sync(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001960 struct cfq_queue *cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 unsigned long flags;
1962
1963 might_sleep_if(gfp_mask & __GFP_WAIT);
1964
Jens Axboee2d74ac2006-03-28 08:59:01 +02001965 cic = cfq_get_io_context(cfqd, gfp_mask);
Jens Axboe22e2c502005-06-27 10:55:12 +02001966
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 spin_lock_irqsave(q->queue_lock, flags);
1968
Jens Axboe22e2c502005-06-27 10:55:12 +02001969 if (!cic)
1970 goto queue_fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971
Vasily Tarasov91fac312007-04-25 12:29:51 +02001972 cfqq = cic_to_cfqq(cic, is_sync);
1973 if (!cfqq) {
Jens Axboefd0928d2008-01-24 08:52:45 +01001974 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001975
Jens Axboe22e2c502005-06-27 10:55:12 +02001976 if (!cfqq)
1977 goto queue_fail;
1978
Vasily Tarasov91fac312007-04-25 12:29:51 +02001979 cic_set_cfqq(cic, cfqq, is_sync);
1980 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981
1982 cfqq->allocated[rw]++;
Jens Axboe3b181522005-06-27 10:56:24 +02001983 cfq_clear_cfqq_must_alloc(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001984 atomic_inc(&cfqq->ref);
Jens Axboe5e705372006-07-13 12:39:25 +02001985
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 spin_unlock_irqrestore(q->queue_lock, flags);
1987
Jens Axboe5e705372006-07-13 12:39:25 +02001988 rq->elevator_private = cic;
1989 rq->elevator_private2 = cfqq;
1990 return 0;
Jens Axboe3b181522005-06-27 10:56:24 +02001991
Jens Axboe22e2c502005-06-27 10:55:12 +02001992queue_fail:
1993 if (cic)
1994 put_io_context(cic->ioc);
Jens Axboe89850f72006-07-22 16:48:31 +02001995
Jens Axboe3b181522005-06-27 10:56:24 +02001996 cfq_schedule_dispatch(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997 spin_unlock_irqrestore(q->queue_lock, flags);
1998 return 1;
1999}
2000
David Howells65f27f32006-11-22 14:55:48 +00002001static void cfq_kick_queue(struct work_struct *work)
Jens Axboe22e2c502005-06-27 10:55:12 +02002002{
David Howells65f27f32006-11-22 14:55:48 +00002003 struct cfq_data *cfqd =
2004 container_of(work, struct cfq_data, unplug_work);
Jens Axboe165125e2007-07-24 09:28:11 +02002005 struct request_queue *q = cfqd->queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02002006 unsigned long flags;
2007
2008 spin_lock_irqsave(q->queue_lock, flags);
Jens Axboedc72ef42006-07-20 14:54:05 +02002009 blk_start_queueing(q);
Jens Axboe22e2c502005-06-27 10:55:12 +02002010 spin_unlock_irqrestore(q->queue_lock, flags);
2011}
2012
2013/*
2014 * Timer running if the active_queue is currently idling inside its time slice
2015 */
2016static void cfq_idle_slice_timer(unsigned long data)
2017{
2018 struct cfq_data *cfqd = (struct cfq_data *) data;
2019 struct cfq_queue *cfqq;
2020 unsigned long flags;
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11002021 int timed_out = 1;
Jens Axboe22e2c502005-06-27 10:55:12 +02002022
2023 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2024
Jens Axboefe094d92008-01-31 13:08:54 +01002025 cfqq = cfqd->active_queue;
2026 if (cfqq) {
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11002027 timed_out = 0;
2028
Jens Axboe22e2c502005-06-27 10:55:12 +02002029 /*
2030 * expired
2031 */
Jens Axboe44f7c162007-01-19 11:51:58 +11002032 if (cfq_slice_used(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02002033 goto expire;
2034
2035 /*
2036 * only expire and reinvoke request handler, if there are
2037 * other queues with pending requests
2038 */
Jens Axboecaaa5f92006-06-16 11:23:00 +02002039 if (!cfqd->busy_queues)
Jens Axboe22e2c502005-06-27 10:55:12 +02002040 goto out_cont;
Jens Axboe22e2c502005-06-27 10:55:12 +02002041
2042 /*
2043 * not expired and it has a request pending, let it dispatch
2044 */
Jens Axboedd67d052006-06-21 09:36:18 +02002045 if (!RB_EMPTY_ROOT(&cfqq->sort_list)) {
Jens Axboe3b181522005-06-27 10:56:24 +02002046 cfq_mark_cfqq_must_dispatch(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002047 goto out_kick;
2048 }
2049 }
2050expire:
Jens Axboe6084cdd2007-04-23 08:25:00 +02002051 cfq_slice_expired(cfqd, timed_out);
Jens Axboe22e2c502005-06-27 10:55:12 +02002052out_kick:
Jens Axboe3b181522005-06-27 10:56:24 +02002053 cfq_schedule_dispatch(cfqd);
Jens Axboe22e2c502005-06-27 10:55:12 +02002054out_cont:
2055 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2056}
2057
Jens Axboe3b181522005-06-27 10:56:24 +02002058static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2059{
2060 del_timer_sync(&cfqd->idle_slice_timer);
Oleg Nesterov43108642007-10-23 15:08:18 +02002061 kblockd_flush_work(&cfqd->unplug_work);
Jens Axboe3b181522005-06-27 10:56:24 +02002062}
Jens Axboe22e2c502005-06-27 10:55:12 +02002063
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002064static void cfq_put_async_queues(struct cfq_data *cfqd)
2065{
2066 int i;
2067
2068 for (i = 0; i < IOPRIO_BE_NR; i++) {
2069 if (cfqd->async_cfqq[0][i])
2070 cfq_put_queue(cfqd->async_cfqq[0][i]);
2071 if (cfqd->async_cfqq[1][i])
2072 cfq_put_queue(cfqd->async_cfqq[1][i]);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002073 }
Oleg Nesterov2389d1e2007-11-05 08:58:05 +01002074
2075 if (cfqd->async_idle_cfqq)
2076 cfq_put_queue(cfqd->async_idle_cfqq);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002077}
2078
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079static void cfq_exit_queue(elevator_t *e)
2080{
Jens Axboe22e2c502005-06-27 10:55:12 +02002081 struct cfq_data *cfqd = e->elevator_data;
Jens Axboe165125e2007-07-24 09:28:11 +02002082 struct request_queue *q = cfqd->queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02002083
Jens Axboe3b181522005-06-27 10:56:24 +02002084 cfq_shutdown_timer_wq(cfqd);
Jens Axboee2d74ac2006-03-28 08:59:01 +02002085
Al Virod9ff4182006-03-18 13:51:22 -05002086 spin_lock_irq(q->queue_lock);
Jens Axboee2d74ac2006-03-28 08:59:01 +02002087
Al Virod9ff4182006-03-18 13:51:22 -05002088 if (cfqd->active_queue)
Jens Axboe6084cdd2007-04-23 08:25:00 +02002089 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
Jens Axboee2d74ac2006-03-28 08:59:01 +02002090
2091 while (!list_empty(&cfqd->cic_list)) {
Al Virod9ff4182006-03-18 13:51:22 -05002092 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2093 struct cfq_io_context,
2094 queue_list);
Jens Axboe89850f72006-07-22 16:48:31 +02002095
2096 __cfq_exit_single_io_context(cfqd, cic);
Al Virod9ff4182006-03-18 13:51:22 -05002097 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02002098
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002099 cfq_put_async_queues(cfqd);
Jens Axboe15c31be2007-07-10 13:43:25 +02002100
Al Virod9ff4182006-03-18 13:51:22 -05002101 spin_unlock_irq(q->queue_lock);
Al Viroa90d7422006-03-18 12:05:37 -05002102
2103 cfq_shutdown_timer_wq(cfqd);
2104
Al Viroa90d7422006-03-18 12:05:37 -05002105 kfree(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106}
2107
Jens Axboe165125e2007-07-24 09:28:11 +02002108static void *cfq_init_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109{
2110 struct cfq_data *cfqd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111
Christoph Lameter94f60302007-07-17 04:03:29 -07002112 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 if (!cfqd)
Jens Axboebc1c1162006-06-08 08:49:06 +02002114 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115
Jens Axboecc09e292007-04-26 12:53:50 +02002116 cfqd->service_tree = CFQ_RB_ROOT;
Al Virod9ff4182006-03-18 13:51:22 -05002117 INIT_LIST_HEAD(&cfqd->cic_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119 cfqd->queue = q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002120
Jens Axboe22e2c502005-06-27 10:55:12 +02002121 init_timer(&cfqd->idle_slice_timer);
2122 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2123 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2124
David Howells65f27f32006-11-22 14:55:48 +00002125 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02002126
Oleg Nesterovb70c8642007-11-07 09:46:13 +01002127 cfqd->last_end_request = jiffies;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 cfqd->cfq_quantum = cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +02002129 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2130 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 cfqd->cfq_back_max = cfq_back_max;
2132 cfqd->cfq_back_penalty = cfq_back_penalty;
Jens Axboe22e2c502005-06-27 10:55:12 +02002133 cfqd->cfq_slice[0] = cfq_slice_async;
2134 cfqd->cfq_slice[1] = cfq_slice_sync;
2135 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2136 cfqd->cfq_slice_idle = cfq_slice_idle;
Jens Axboe3b181522005-06-27 10:56:24 +02002137
Jens Axboebc1c1162006-06-08 08:49:06 +02002138 return cfqd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139}
2140
2141static void cfq_slab_kill(void)
2142{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143 if (cfq_pool)
2144 kmem_cache_destroy(cfq_pool);
2145 if (cfq_ioc_pool)
2146 kmem_cache_destroy(cfq_ioc_pool);
2147}
2148
2149static int __init cfq_slab_setup(void)
2150{
Christoph Lameter0a31bd52007-05-06 14:49:57 -07002151 cfq_pool = KMEM_CACHE(cfq_queue, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152 if (!cfq_pool)
2153 goto fail;
2154
Jens Axboe4ac845a2008-01-24 08:44:49 +01002155 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, SLAB_DESTROY_BY_RCU);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 if (!cfq_ioc_pool)
2157 goto fail;
2158
2159 return 0;
2160fail:
2161 cfq_slab_kill();
2162 return -ENOMEM;
2163}
2164
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165/*
2166 * sysfs parts below -->
2167 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168static ssize_t
2169cfq_var_show(unsigned int var, char *page)
2170{
2171 return sprintf(page, "%d\n", var);
2172}
2173
2174static ssize_t
2175cfq_var_store(unsigned int *var, const char *page, size_t count)
2176{
2177 char *p = (char *) page;
2178
2179 *var = simple_strtoul(p, &p, 10);
2180 return count;
2181}
2182
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
Al Viro3d1ab402006-03-18 18:35:43 -05002184static ssize_t __FUNC(elevator_t *e, char *page) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185{ \
Al Viro3d1ab402006-03-18 18:35:43 -05002186 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187 unsigned int __data = __VAR; \
2188 if (__CONV) \
2189 __data = jiffies_to_msecs(__data); \
2190 return cfq_var_show(__data, (page)); \
2191}
2192SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02002193SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2194SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
Al Viroe572ec72006-03-18 22:27:18 -05002195SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2196SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02002197SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2198SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2199SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2200SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201#undef SHOW_FUNCTION
2202
2203#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
Al Viro3d1ab402006-03-18 18:35:43 -05002204static ssize_t __FUNC(elevator_t *e, const char *page, size_t count) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205{ \
Al Viro3d1ab402006-03-18 18:35:43 -05002206 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 unsigned int __data; \
2208 int ret = cfq_var_store(&__data, (page), count); \
2209 if (__data < (MIN)) \
2210 __data = (MIN); \
2211 else if (__data > (MAX)) \
2212 __data = (MAX); \
2213 if (__CONV) \
2214 *(__PTR) = msecs_to_jiffies(__data); \
2215 else \
2216 *(__PTR) = __data; \
2217 return ret; \
2218}
2219STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01002220STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2221 UINT_MAX, 1);
2222STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2223 UINT_MAX, 1);
Al Viroe572ec72006-03-18 22:27:18 -05002224STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01002225STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2226 UINT_MAX, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02002227STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2228STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2229STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
Jens Axboefe094d92008-01-31 13:08:54 +01002230STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2231 UINT_MAX, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232#undef STORE_FUNCTION
2233
Al Viroe572ec72006-03-18 22:27:18 -05002234#define CFQ_ATTR(name) \
2235 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
Jens Axboe3b181522005-06-27 10:56:24 +02002236
Al Viroe572ec72006-03-18 22:27:18 -05002237static struct elv_fs_entry cfq_attrs[] = {
2238 CFQ_ATTR(quantum),
Al Viroe572ec72006-03-18 22:27:18 -05002239 CFQ_ATTR(fifo_expire_sync),
2240 CFQ_ATTR(fifo_expire_async),
2241 CFQ_ATTR(back_seek_max),
2242 CFQ_ATTR(back_seek_penalty),
2243 CFQ_ATTR(slice_sync),
2244 CFQ_ATTR(slice_async),
2245 CFQ_ATTR(slice_async_rq),
2246 CFQ_ATTR(slice_idle),
Al Viroe572ec72006-03-18 22:27:18 -05002247 __ATTR_NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248};
2249
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250static struct elevator_type iosched_cfq = {
2251 .ops = {
2252 .elevator_merge_fn = cfq_merge,
2253 .elevator_merged_fn = cfq_merged_request,
2254 .elevator_merge_req_fn = cfq_merged_requests,
Jens Axboeda775262006-12-20 11:04:12 +01002255 .elevator_allow_merge_fn = cfq_allow_merge,
Jens Axboeb4878f22005-10-20 16:42:29 +02002256 .elevator_dispatch_fn = cfq_dispatch_requests,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 .elevator_add_req_fn = cfq_insert_request,
Jens Axboeb4878f22005-10-20 16:42:29 +02002258 .elevator_activate_req_fn = cfq_activate_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259 .elevator_deactivate_req_fn = cfq_deactivate_request,
2260 .elevator_queue_empty_fn = cfq_queue_empty,
2261 .elevator_completed_req_fn = cfq_completed_request,
Jens Axboe21183b02006-07-13 12:33:14 +02002262 .elevator_former_req_fn = elv_rb_former_request,
2263 .elevator_latter_req_fn = elv_rb_latter_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 .elevator_set_req_fn = cfq_set_request,
2265 .elevator_put_req_fn = cfq_put_request,
2266 .elevator_may_queue_fn = cfq_may_queue,
2267 .elevator_init_fn = cfq_init_queue,
2268 .elevator_exit_fn = cfq_exit_queue,
Jens Axboefc463792006-08-29 09:05:44 +02002269 .trim = cfq_free_io_context,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 },
Al Viro3d1ab402006-03-18 18:35:43 -05002271 .elevator_attrs = cfq_attrs,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 .elevator_name = "cfq",
2273 .elevator_owner = THIS_MODULE,
2274};
2275
2276static int __init cfq_init(void)
2277{
Jens Axboe22e2c502005-06-27 10:55:12 +02002278 /*
2279 * could be 0 on HZ < 1000 setups
2280 */
2281 if (!cfq_slice_async)
2282 cfq_slice_async = 1;
2283 if (!cfq_slice_idle)
2284 cfq_slice_idle = 1;
2285
Linus Torvalds1da177e2005-04-16 15:20:36 -07002286 if (cfq_slab_setup())
2287 return -ENOMEM;
2288
Adrian Bunk2fdd82b2007-12-12 18:51:56 +01002289 elv_register(&iosched_cfq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002290
Adrian Bunk2fdd82b2007-12-12 18:51:56 +01002291 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292}
2293
2294static void __exit cfq_exit(void)
2295{
Peter Zijlstra6e9a4732006-09-30 23:28:10 -07002296 DECLARE_COMPLETION_ONSTACK(all_gone);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297 elv_unregister(&iosched_cfq);
Al Viro334e94d2006-03-18 15:05:53 -05002298 ioc_gone = &all_gone;
OGAWA Hirofumifba82272006-04-18 09:44:06 +02002299 /* ioc_gone's update must be visible before reading ioc_count */
2300 smp_wmb();
Jens Axboe4050cf12006-07-19 05:07:12 +02002301 if (elv_ioc_count_read(ioc_count))
OGAWA Hirofumifba82272006-04-18 09:44:06 +02002302 wait_for_completion(ioc_gone);
Al Viro334e94d2006-03-18 15:05:53 -05002303 synchronize_rcu();
Christoph Hellwig83521d32005-10-30 15:01:39 -08002304 cfq_slab_kill();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002305}
2306
2307module_init(cfq_init);
2308module_exit(cfq_exit);
2309
2310MODULE_AUTHOR("Jens Axboe");
2311MODULE_LICENSE("GPL");
2312MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");