blob: a9664fa0b6097ace6a48d48e0992a6d83ed32a9d [file] [log] [blame]
Vivek Goyale43473b2010-09-15 17:06:35 -04001/*
2 * Interface for controlling IO bandwidth on a request queue
3 *
4 * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
5 */
6
7#include <linux/module.h>
8#include <linux/slab.h>
9#include <linux/blkdev.h>
10#include <linux/bio.h>
11#include <linux/blktrace_api.h>
12#include "blk-cgroup.h"
Tejun Heobc9fcbf2011-10-19 14:31:18 +020013#include "blk.h"
Vivek Goyale43473b2010-09-15 17:06:35 -040014
15/* Max dispatch from a group in 1 round */
16static int throtl_grp_quantum = 8;
17
18/* Total max dispatch from all groups in one round */
19static int throtl_quantum = 32;
20
21/* Throttling is performed over 100ms slice and after that slice is renewed */
22static unsigned long throtl_slice = HZ/10; /* 100 ms */
23
Tejun Heo3c798392012-04-16 13:57:25 -070024static struct blkcg_policy blkcg_policy_throtl;
Tejun Heo03814112012-03-05 13:15:14 -080025
Vivek Goyal450adcb2011-03-01 13:40:54 -050026/* A workqueue to queue throttle related work */
27static struct workqueue_struct *kthrotld_workqueue;
28static void throtl_schedule_delayed_work(struct throtl_data *td,
29 unsigned long delay);
30
Vivek Goyale43473b2010-09-15 17:06:35 -040031struct throtl_rb_root {
32 struct rb_root rb;
33 struct rb_node *left;
34 unsigned int count;
35 unsigned long min_disptime;
36};
37
38#define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
39 .count = 0, .min_disptime = 0}
40
41#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
42
Tejun Heo8a3d2612012-04-01 14:38:44 -070043/* Per-cpu group stats */
44struct tg_stats_cpu {
45 /* total bytes transferred */
46 struct blkg_rwstat service_bytes;
47 /* total IOs serviced, post merge */
48 struct blkg_rwstat serviced;
49};
50
Vivek Goyale43473b2010-09-15 17:06:35 -040051struct throtl_grp {
Tejun Heof95a04a2012-04-16 13:57:26 -070052 /* must be the first member */
53 struct blkg_policy_data pd;
54
Vivek Goyale43473b2010-09-15 17:06:35 -040055 /* active throtl group service_tree member */
56 struct rb_node rb_node;
57
58 /*
59 * Dispatch time in jiffies. This is the estimated time when group
60 * will unthrottle and is ready to dispatch more bio. It is used as
61 * key to sort active groups in service tree.
62 */
63 unsigned long disptime;
64
Vivek Goyale43473b2010-09-15 17:06:35 -040065 unsigned int flags;
66
67 /* Two lists for READ and WRITE */
68 struct bio_list bio_lists[2];
69
70 /* Number of queued bios on READ and WRITE lists */
71 unsigned int nr_queued[2];
72
73 /* bytes per second rate limits */
74 uint64_t bps[2];
75
Vivek Goyal8e89d132010-09-15 17:06:37 -040076 /* IOPS limits */
77 unsigned int iops[2];
78
Vivek Goyale43473b2010-09-15 17:06:35 -040079 /* Number of bytes disptached in current slice */
80 uint64_t bytes_disp[2];
Vivek Goyal8e89d132010-09-15 17:06:37 -040081 /* Number of bio's dispatched in current slice */
82 unsigned int io_disp[2];
Vivek Goyale43473b2010-09-15 17:06:35 -040083
84 /* When did we start a new slice */
85 unsigned long slice_start[2];
86 unsigned long slice_end[2];
Vivek Goyalfe071432010-10-01 14:49:49 +020087
88 /* Some throttle limits got updated for the group */
Andreas Schwab6f037932011-03-30 12:21:56 +020089 int limits_changed;
Tejun Heo8a3d2612012-04-01 14:38:44 -070090
91 /* Per cpu stats pointer */
92 struct tg_stats_cpu __percpu *stats_cpu;
93
94 /* List of tgs waiting for per cpu stats memory to be allocated */
95 struct list_head stats_alloc_node;
Vivek Goyale43473b2010-09-15 17:06:35 -040096};
97
98struct throtl_data
99{
Vivek Goyale43473b2010-09-15 17:06:35 -0400100 /* service tree for active throtl groups */
101 struct throtl_rb_root tg_service_tree;
102
Vivek Goyale43473b2010-09-15 17:06:35 -0400103 struct request_queue *queue;
104
105 /* Total Number of queued bios on READ and WRITE lists */
106 unsigned int nr_queued[2];
107
108 /*
Vivek Goyal02977e42010-10-01 14:49:48 +0200109 * number of total undestroyed groups
Vivek Goyale43473b2010-09-15 17:06:35 -0400110 */
111 unsigned int nr_undestroyed_grps;
112
113 /* Work for dispatching throttled bios */
114 struct delayed_work throtl_work;
Vivek Goyalfe071432010-10-01 14:49:49 +0200115
Andreas Schwab6f037932011-03-30 12:21:56 +0200116 int limits_changed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400117};
118
Tejun Heo8a3d2612012-04-01 14:38:44 -0700119/* list and work item to allocate percpu group stats */
120static DEFINE_SPINLOCK(tg_stats_alloc_lock);
121static LIST_HEAD(tg_stats_alloc_list);
122
123static void tg_stats_alloc_fn(struct work_struct *);
124static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn);
125
Tejun Heof95a04a2012-04-16 13:57:26 -0700126static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd)
127{
128 return pd ? container_of(pd, struct throtl_grp, pd) : NULL;
129}
130
Tejun Heo3c798392012-04-16 13:57:25 -0700131static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg)
Tejun Heo03814112012-03-05 13:15:14 -0800132{
Tejun Heof95a04a2012-04-16 13:57:26 -0700133 return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl));
Tejun Heo03814112012-03-05 13:15:14 -0800134}
135
Tejun Heo3c798392012-04-16 13:57:25 -0700136static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg)
Tejun Heo03814112012-03-05 13:15:14 -0800137{
Tejun Heof95a04a2012-04-16 13:57:26 -0700138 return pd_to_blkg(&tg->pd);
Tejun Heo03814112012-03-05 13:15:14 -0800139}
140
Tejun Heo03d8e112012-04-13 13:11:32 -0700141static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
142{
143 return blkg_to_tg(td->queue->root_blkg);
144}
145
Vivek Goyale43473b2010-09-15 17:06:35 -0400146enum tg_state_flags {
147 THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
148};
149
150#define THROTL_TG_FNS(name) \
151static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
152{ \
153 (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
154} \
155static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
156{ \
157 (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
158} \
159static inline int throtl_tg_##name(const struct throtl_grp *tg) \
160{ \
161 return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
162}
163
164THROTL_TG_FNS(on_rr);
165
Tejun Heo54e7ed12012-04-16 13:57:23 -0700166#define throtl_log_tg(td, tg, fmt, args...) do { \
167 char __pbuf[128]; \
168 \
169 blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf)); \
170 blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \
171} while (0)
Vivek Goyale43473b2010-09-15 17:06:35 -0400172
173#define throtl_log(td, fmt, args...) \
174 blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
175
Joe Perchesd2f31a52011-06-13 20:19:27 +0200176static inline unsigned int total_nr_queued(struct throtl_data *td)
Vivek Goyale43473b2010-09-15 17:06:35 -0400177{
Joe Perchesd2f31a52011-06-13 20:19:27 +0200178 return td->nr_queued[0] + td->nr_queued[1];
Vivek Goyale43473b2010-09-15 17:06:35 -0400179}
180
Tejun Heo8a3d2612012-04-01 14:38:44 -0700181/*
182 * Worker for allocating per cpu stat for tgs. This is scheduled on the
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700183 * system_wq once there are some groups on the alloc_list waiting for
Tejun Heo8a3d2612012-04-01 14:38:44 -0700184 * allocation.
185 */
186static void tg_stats_alloc_fn(struct work_struct *work)
187{
188 static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */
189 struct delayed_work *dwork = to_delayed_work(work);
190 bool empty = false;
191
192alloc_stats:
193 if (!stats_cpu) {
194 stats_cpu = alloc_percpu(struct tg_stats_cpu);
195 if (!stats_cpu) {
196 /* allocation failed, try again after some time */
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700197 schedule_delayed_work(dwork, msecs_to_jiffies(10));
Tejun Heo8a3d2612012-04-01 14:38:44 -0700198 return;
199 }
200 }
201
202 spin_lock_irq(&tg_stats_alloc_lock);
203
204 if (!list_empty(&tg_stats_alloc_list)) {
205 struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
206 struct throtl_grp,
207 stats_alloc_node);
208 swap(tg->stats_cpu, stats_cpu);
209 list_del_init(&tg->stats_alloc_node);
210 }
211
212 empty = list_empty(&tg_stats_alloc_list);
213 spin_unlock_irq(&tg_stats_alloc_lock);
214 if (!empty)
215 goto alloc_stats;
216}
217
Tejun Heo3c798392012-04-16 13:57:25 -0700218static void throtl_pd_init(struct blkcg_gq *blkg)
Vivek Goyala29a1712011-05-19 15:38:19 -0400219{
Tejun Heo03814112012-03-05 13:15:14 -0800220 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200221 unsigned long flags;
Tejun Heocd1604f2012-03-05 13:15:06 -0800222
Vivek Goyala29a1712011-05-19 15:38:19 -0400223 RB_CLEAR_NODE(&tg->rb_node);
224 bio_list_init(&tg->bio_lists[0]);
225 bio_list_init(&tg->bio_lists[1]);
226 tg->limits_changed = false;
227
Tejun Heoe56da7e2012-03-05 13:15:07 -0800228 tg->bps[READ] = -1;
229 tg->bps[WRITE] = -1;
230 tg->iops[READ] = -1;
231 tg->iops[WRITE] = -1;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700232
233 /*
234 * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
235 * but percpu allocator can't be called from IO path. Queue tg on
236 * tg_stats_alloc_list and allocate from work item.
237 */
Tejun Heoff26eaa2012-05-23 12:16:21 +0200238 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700239 list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
Tejun Heo3b07e9c2012-08-20 14:51:24 -0700240 schedule_delayed_work(&tg_stats_alloc_work, 0);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200241 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700242}
243
Tejun Heo3c798392012-04-16 13:57:25 -0700244static void throtl_pd_exit(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700245{
246 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200247 unsigned long flags;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700248
Tejun Heoff26eaa2012-05-23 12:16:21 +0200249 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700250 list_del_init(&tg->stats_alloc_node);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200251 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700252
253 free_percpu(tg->stats_cpu);
254}
255
Tejun Heo3c798392012-04-16 13:57:25 -0700256static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700257{
258 struct throtl_grp *tg = blkg_to_tg(blkg);
259 int cpu;
260
261 if (tg->stats_cpu == NULL)
262 return;
263
264 for_each_possible_cpu(cpu) {
265 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
266
267 blkg_rwstat_reset(&sc->service_bytes);
268 blkg_rwstat_reset(&sc->serviced);
269 }
Vivek Goyala29a1712011-05-19 15:38:19 -0400270}
271
Tejun Heo3c798392012-04-16 13:57:25 -0700272static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
273 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400274{
Vivek Goyale43473b2010-09-15 17:06:35 -0400275 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700276 * This is the common case when there are no blkcgs. Avoid lookup
277 * in this case
Tejun Heocd1604f2012-03-05 13:15:06 -0800278 */
Tejun Heo3c798392012-04-16 13:57:25 -0700279 if (blkcg == &blkcg_root)
Tejun Heo03d8e112012-04-13 13:11:32 -0700280 return td_root_tg(td);
Vivek Goyale43473b2010-09-15 17:06:35 -0400281
Tejun Heoe8989fa2012-03-05 13:15:20 -0800282 return blkg_to_tg(blkg_lookup(blkcg, td->queue));
Vivek Goyale43473b2010-09-15 17:06:35 -0400283}
284
Tejun Heocd1604f2012-03-05 13:15:06 -0800285static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
Tejun Heo3c798392012-04-16 13:57:25 -0700286 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400287{
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400288 struct request_queue *q = td->queue;
Tejun Heocd1604f2012-03-05 13:15:06 -0800289 struct throtl_grp *tg = NULL;
Tejun Heo0a5a7d02012-03-05 13:15:02 -0800290
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400291 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700292 * This is the common case when there are no blkcgs. Avoid lookup
293 * in this case
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400294 */
Tejun Heo3c798392012-04-16 13:57:25 -0700295 if (blkcg == &blkcg_root) {
Tejun Heo03d8e112012-04-13 13:11:32 -0700296 tg = td_root_tg(td);
Tejun Heocd1604f2012-03-05 13:15:06 -0800297 } else {
Tejun Heo3c798392012-04-16 13:57:25 -0700298 struct blkcg_gq *blkg;
Tejun Heocd1604f2012-03-05 13:15:06 -0800299
Tejun Heo3c96cb32012-04-13 13:11:34 -0700300 blkg = blkg_lookup_create(blkcg, q);
Tejun Heocd1604f2012-03-05 13:15:06 -0800301
302 /* if %NULL and @q is alive, fall back to root_tg */
303 if (!IS_ERR(blkg))
Tejun Heo03814112012-03-05 13:15:14 -0800304 tg = blkg_to_tg(blkg);
Tejun Heocd1604f2012-03-05 13:15:06 -0800305 else if (!blk_queue_dead(q))
Tejun Heo03d8e112012-04-13 13:11:32 -0700306 tg = td_root_tg(td);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400307 }
308
Vivek Goyale43473b2010-09-15 17:06:35 -0400309 return tg;
310}
311
312static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
313{
314 /* Service tree is empty */
315 if (!root->count)
316 return NULL;
317
318 if (!root->left)
319 root->left = rb_first(&root->rb);
320
321 if (root->left)
322 return rb_entry_tg(root->left);
323
324 return NULL;
325}
326
327static void rb_erase_init(struct rb_node *n, struct rb_root *root)
328{
329 rb_erase(n, root);
330 RB_CLEAR_NODE(n);
331}
332
333static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root)
334{
335 if (root->left == n)
336 root->left = NULL;
337 rb_erase_init(n, &root->rb);
338 --root->count;
339}
340
341static void update_min_dispatch_time(struct throtl_rb_root *st)
342{
343 struct throtl_grp *tg;
344
345 tg = throtl_rb_first(st);
346 if (!tg)
347 return;
348
349 st->min_disptime = tg->disptime;
350}
351
352static void
353tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
354{
355 struct rb_node **node = &st->rb.rb_node;
356 struct rb_node *parent = NULL;
357 struct throtl_grp *__tg;
358 unsigned long key = tg->disptime;
359 int left = 1;
360
361 while (*node != NULL) {
362 parent = *node;
363 __tg = rb_entry_tg(parent);
364
365 if (time_before(key, __tg->disptime))
366 node = &parent->rb_left;
367 else {
368 node = &parent->rb_right;
369 left = 0;
370 }
371 }
372
373 if (left)
374 st->left = &tg->rb_node;
375
376 rb_link_node(&tg->rb_node, parent, node);
377 rb_insert_color(&tg->rb_node, &st->rb);
378}
379
380static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
381{
382 struct throtl_rb_root *st = &td->tg_service_tree;
383
384 tg_service_tree_add(st, tg);
385 throtl_mark_tg_on_rr(tg);
386 st->count++;
387}
388
389static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
390{
391 if (!throtl_tg_on_rr(tg))
392 __throtl_enqueue_tg(td, tg);
393}
394
395static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
396{
397 throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
398 throtl_clear_tg_on_rr(tg);
399}
400
401static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
402{
403 if (throtl_tg_on_rr(tg))
404 __throtl_dequeue_tg(td, tg);
405}
406
407static void throtl_schedule_next_dispatch(struct throtl_data *td)
408{
409 struct throtl_rb_root *st = &td->tg_service_tree;
410
411 /*
412 * If there are more bios pending, schedule more work.
413 */
414 if (!total_nr_queued(td))
415 return;
416
417 BUG_ON(!st->count);
418
419 update_min_dispatch_time(st);
420
421 if (time_before_eq(st->min_disptime, jiffies))
Vivek Goyal450adcb2011-03-01 13:40:54 -0500422 throtl_schedule_delayed_work(td, 0);
Vivek Goyale43473b2010-09-15 17:06:35 -0400423 else
Vivek Goyal450adcb2011-03-01 13:40:54 -0500424 throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
Vivek Goyale43473b2010-09-15 17:06:35 -0400425}
426
427static inline void
428throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
429{
430 tg->bytes_disp[rw] = 0;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400431 tg->io_disp[rw] = 0;
Vivek Goyale43473b2010-09-15 17:06:35 -0400432 tg->slice_start[rw] = jiffies;
433 tg->slice_end[rw] = jiffies + throtl_slice;
434 throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
435 rw == READ ? 'R' : 'W', tg->slice_start[rw],
436 tg->slice_end[rw], jiffies);
437}
438
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100439static inline void throtl_set_slice_end(struct throtl_data *td,
440 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
441{
442 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
443}
444
Vivek Goyale43473b2010-09-15 17:06:35 -0400445static inline void throtl_extend_slice(struct throtl_data *td,
446 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
447{
448 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
449 throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
450 rw == READ ? 'R' : 'W', tg->slice_start[rw],
451 tg->slice_end[rw], jiffies);
452}
453
454/* Determine if previously allocated or extended slice is complete or not */
455static bool
456throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
457{
458 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
459 return 0;
460
461 return 1;
462}
463
464/* Trim the used slices and adjust slice start accordingly */
465static inline void
466throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
467{
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200468 unsigned long nr_slices, time_elapsed, io_trim;
469 u64 bytes_trim, tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400470
471 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
472
473 /*
474 * If bps are unlimited (-1), then time slice don't get
475 * renewed. Don't try to trim the slice if slice is used. A new
476 * slice will start when appropriate.
477 */
478 if (throtl_slice_used(td, tg, rw))
479 return;
480
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100481 /*
482 * A bio has been dispatched. Also adjust slice_end. It might happen
483 * that initially cgroup limit was very low resulting in high
484 * slice_end, but later limit was bumped up and bio was dispached
485 * sooner, then we need to reduce slice_end. A high bogus slice_end
486 * is bad because it does not allow new slice to start.
487 */
488
489 throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
490
Vivek Goyale43473b2010-09-15 17:06:35 -0400491 time_elapsed = jiffies - tg->slice_start[rw];
492
493 nr_slices = time_elapsed / throtl_slice;
494
495 if (!nr_slices)
496 return;
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200497 tmp = tg->bps[rw] * throtl_slice * nr_slices;
498 do_div(tmp, HZ);
499 bytes_trim = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400500
Vivek Goyal8e89d132010-09-15 17:06:37 -0400501 io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
Vivek Goyale43473b2010-09-15 17:06:35 -0400502
Vivek Goyal8e89d132010-09-15 17:06:37 -0400503 if (!bytes_trim && !io_trim)
Vivek Goyale43473b2010-09-15 17:06:35 -0400504 return;
505
506 if (tg->bytes_disp[rw] >= bytes_trim)
507 tg->bytes_disp[rw] -= bytes_trim;
508 else
509 tg->bytes_disp[rw] = 0;
510
Vivek Goyal8e89d132010-09-15 17:06:37 -0400511 if (tg->io_disp[rw] >= io_trim)
512 tg->io_disp[rw] -= io_trim;
513 else
514 tg->io_disp[rw] = 0;
515
Vivek Goyale43473b2010-09-15 17:06:35 -0400516 tg->slice_start[rw] += nr_slices * throtl_slice;
517
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200518 throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
Vivek Goyale43473b2010-09-15 17:06:35 -0400519 " start=%lu end=%lu jiffies=%lu",
Vivek Goyal8e89d132010-09-15 17:06:37 -0400520 rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
Vivek Goyale43473b2010-09-15 17:06:35 -0400521 tg->slice_start[rw], tg->slice_end[rw], jiffies);
522}
523
Vivek Goyal8e89d132010-09-15 17:06:37 -0400524static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
525 struct bio *bio, unsigned long *wait)
Vivek Goyale43473b2010-09-15 17:06:35 -0400526{
527 bool rw = bio_data_dir(bio);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400528 unsigned int io_allowed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400529 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200530 u64 tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400531
Vivek Goyal8e89d132010-09-15 17:06:37 -0400532 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
Vivek Goyale43473b2010-09-15 17:06:35 -0400533
Vivek Goyal8e89d132010-09-15 17:06:37 -0400534 /* Slice has just started. Consider one slice interval */
535 if (!jiffy_elapsed)
536 jiffy_elapsed_rnd = throtl_slice;
537
538 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
539
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200540 /*
541 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
542 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
543 * will allow dispatch after 1 second and after that slice should
544 * have been trimmed.
545 */
546
547 tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
548 do_div(tmp, HZ);
549
550 if (tmp > UINT_MAX)
551 io_allowed = UINT_MAX;
552 else
553 io_allowed = tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400554
555 if (tg->io_disp[rw] + 1 <= io_allowed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400556 if (wait)
557 *wait = 0;
558 return 1;
559 }
560
Vivek Goyal8e89d132010-09-15 17:06:37 -0400561 /* Calc approx time to dispatch */
562 jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
563
564 if (jiffy_wait > jiffy_elapsed)
565 jiffy_wait = jiffy_wait - jiffy_elapsed;
566 else
567 jiffy_wait = 1;
568
569 if (wait)
570 *wait = jiffy_wait;
571 return 0;
572}
573
574static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
575 struct bio *bio, unsigned long *wait)
576{
577 bool rw = bio_data_dir(bio);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200578 u64 bytes_allowed, extra_bytes, tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400579 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyale43473b2010-09-15 17:06:35 -0400580
581 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
582
583 /* Slice has just started. Consider one slice interval */
584 if (!jiffy_elapsed)
585 jiffy_elapsed_rnd = throtl_slice;
586
587 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
588
Vivek Goyal5e901a22010-10-01 21:16:38 +0200589 tmp = tg->bps[rw] * jiffy_elapsed_rnd;
590 do_div(tmp, HZ);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200591 bytes_allowed = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400592
593 if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
594 if (wait)
595 *wait = 0;
596 return 1;
597 }
598
599 /* Calc approx time to dispatch */
600 extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
601 jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
602
603 if (!jiffy_wait)
604 jiffy_wait = 1;
605
606 /*
607 * This wait time is without taking into consideration the rounding
608 * up we did. Add that time also.
609 */
610 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
Vivek Goyale43473b2010-09-15 17:06:35 -0400611 if (wait)
612 *wait = jiffy_wait;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400613 return 0;
614}
Vivek Goyale43473b2010-09-15 17:06:35 -0400615
Vivek Goyalaf75cd32011-05-19 15:38:31 -0400616static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
617 if (tg->bps[rw] == -1 && tg->iops[rw] == -1)
618 return 1;
619 return 0;
620}
621
Vivek Goyal8e89d132010-09-15 17:06:37 -0400622/*
623 * Returns whether one can dispatch a bio or not. Also returns approx number
624 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
625 */
626static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
627 struct bio *bio, unsigned long *wait)
628{
629 bool rw = bio_data_dir(bio);
630 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
631
632 /*
633 * Currently whole state machine of group depends on first bio
634 * queued in the group bio list. So one should not be calling
635 * this function with a different bio if there are other bios
636 * queued.
637 */
638 BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
639
640 /* If tg->bps = -1, then BW is unlimited */
641 if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
642 if (wait)
643 *wait = 0;
644 return 1;
645 }
646
647 /*
648 * If previous slice expired, start a new one otherwise renew/extend
649 * existing slice to make sure it is at least throtl_slice interval
650 * long since now.
651 */
652 if (throtl_slice_used(td, tg, rw))
653 throtl_start_new_slice(td, tg, rw);
654 else {
655 if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
656 throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
657 }
658
659 if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
660 && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
661 if (wait)
662 *wait = 0;
663 return 1;
664 }
665
666 max_wait = max(bps_wait, iops_wait);
667
668 if (wait)
669 *wait = max_wait;
670
671 if (time_before(tg->slice_end[rw], jiffies + max_wait))
672 throtl_extend_slice(td, tg, rw, jiffies + max_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -0400673
674 return 0;
675}
676
Tejun Heo3c798392012-04-16 13:57:25 -0700677static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
Tejun Heo629ed0b2012-04-01 14:38:44 -0700678 int rw)
679{
Tejun Heo8a3d2612012-04-01 14:38:44 -0700680 struct throtl_grp *tg = blkg_to_tg(blkg);
681 struct tg_stats_cpu *stats_cpu;
Tejun Heo629ed0b2012-04-01 14:38:44 -0700682 unsigned long flags;
683
684 /* If per cpu stats are not allocated yet, don't do any accounting. */
Tejun Heo8a3d2612012-04-01 14:38:44 -0700685 if (tg->stats_cpu == NULL)
Tejun Heo629ed0b2012-04-01 14:38:44 -0700686 return;
687
688 /*
689 * Disabling interrupts to provide mutual exclusion between two
690 * writes on same cpu. It probably is not needed for 64bit. Not
691 * optimizing that case yet.
692 */
693 local_irq_save(flags);
694
Tejun Heo8a3d2612012-04-01 14:38:44 -0700695 stats_cpu = this_cpu_ptr(tg->stats_cpu);
Tejun Heo629ed0b2012-04-01 14:38:44 -0700696
Tejun Heo629ed0b2012-04-01 14:38:44 -0700697 blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
698 blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
699
700 local_irq_restore(flags);
701}
702
Vivek Goyale43473b2010-09-15 17:06:35 -0400703static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
704{
705 bool rw = bio_data_dir(bio);
Vivek Goyale43473b2010-09-15 17:06:35 -0400706
707 /* Charge the bio to the group */
708 tg->bytes_disp[rw] += bio->bi_size;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400709 tg->io_disp[rw]++;
Vivek Goyale43473b2010-09-15 17:06:35 -0400710
Tejun Heo629ed0b2012-04-01 14:38:44 -0700711 throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw);
Vivek Goyale43473b2010-09-15 17:06:35 -0400712}
713
714static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
715 struct bio *bio)
716{
717 bool rw = bio_data_dir(bio);
718
719 bio_list_add(&tg->bio_lists[rw], bio);
720 /* Take a bio reference on tg */
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800721 blkg_get(tg_to_blkg(tg));
Vivek Goyale43473b2010-09-15 17:06:35 -0400722 tg->nr_queued[rw]++;
723 td->nr_queued[rw]++;
724 throtl_enqueue_tg(td, tg);
725}
726
727static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
728{
729 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
730 struct bio *bio;
731
732 if ((bio = bio_list_peek(&tg->bio_lists[READ])))
733 tg_may_dispatch(td, tg, bio, &read_wait);
734
735 if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
736 tg_may_dispatch(td, tg, bio, &write_wait);
737
738 min_wait = min(read_wait, write_wait);
739 disptime = jiffies + min_wait;
740
Vivek Goyale43473b2010-09-15 17:06:35 -0400741 /* Update dispatch time */
742 throtl_dequeue_tg(td, tg);
743 tg->disptime = disptime;
744 throtl_enqueue_tg(td, tg);
745}
746
747static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
748 bool rw, struct bio_list *bl)
749{
750 struct bio *bio;
751
752 bio = bio_list_pop(&tg->bio_lists[rw]);
753 tg->nr_queued[rw]--;
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800754 /* Drop bio reference on blkg */
755 blkg_put(tg_to_blkg(tg));
Vivek Goyale43473b2010-09-15 17:06:35 -0400756
757 BUG_ON(td->nr_queued[rw] <= 0);
758 td->nr_queued[rw]--;
759
760 throtl_charge_bio(tg, bio);
761 bio_list_add(bl, bio);
762 bio->bi_rw |= REQ_THROTTLED;
763
764 throtl_trim_slice(td, tg, rw);
765}
766
767static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
768 struct bio_list *bl)
769{
770 unsigned int nr_reads = 0, nr_writes = 0;
771 unsigned int max_nr_reads = throtl_grp_quantum*3/4;
Vivek Goyalc2f68052010-11-15 19:32:42 +0100772 unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
Vivek Goyale43473b2010-09-15 17:06:35 -0400773 struct bio *bio;
774
775 /* Try to dispatch 75% READS and 25% WRITES */
776
777 while ((bio = bio_list_peek(&tg->bio_lists[READ]))
778 && tg_may_dispatch(td, tg, bio, NULL)) {
779
780 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
781 nr_reads++;
782
783 if (nr_reads >= max_nr_reads)
784 break;
785 }
786
787 while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
788 && tg_may_dispatch(td, tg, bio, NULL)) {
789
790 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
791 nr_writes++;
792
793 if (nr_writes >= max_nr_writes)
794 break;
795 }
796
797 return nr_reads + nr_writes;
798}
799
800static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl)
801{
802 unsigned int nr_disp = 0;
803 struct throtl_grp *tg;
804 struct throtl_rb_root *st = &td->tg_service_tree;
805
806 while (1) {
807 tg = throtl_rb_first(st);
808
809 if (!tg)
810 break;
811
812 if (time_before(jiffies, tg->disptime))
813 break;
814
815 throtl_dequeue_tg(td, tg);
816
817 nr_disp += throtl_dispatch_tg(td, tg, bl);
818
819 if (tg->nr_queued[0] || tg->nr_queued[1]) {
820 tg_update_disptime(td, tg);
821 throtl_enqueue_tg(td, tg);
822 }
823
824 if (nr_disp >= throtl_quantum)
825 break;
826 }
827
828 return nr_disp;
829}
830
Vivek Goyalfe071432010-10-01 14:49:49 +0200831static void throtl_process_limit_change(struct throtl_data *td)
832{
Tejun Heo4eef3042012-03-05 13:15:18 -0800833 struct request_queue *q = td->queue;
Tejun Heo3c798392012-04-16 13:57:25 -0700834 struct blkcg_gq *blkg, *n;
Vivek Goyalfe071432010-10-01 14:49:49 +0200835
Vivek Goyalde701c72011-03-07 21:09:32 +0100836 if (!td->limits_changed)
Vivek Goyalfe071432010-10-01 14:49:49 +0200837 return;
838
Vivek Goyalde701c72011-03-07 21:09:32 +0100839 xchg(&td->limits_changed, false);
Vivek Goyalfe071432010-10-01 14:49:49 +0200840
Vivek Goyalde701c72011-03-07 21:09:32 +0100841 throtl_log(td, "limits changed");
Vivek Goyalfe071432010-10-01 14:49:49 +0200842
Tejun Heoe8989fa2012-03-05 13:15:20 -0800843 list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
Tejun Heo4eef3042012-03-05 13:15:18 -0800844 struct throtl_grp *tg = blkg_to_tg(blkg);
845
Vivek Goyalde701c72011-03-07 21:09:32 +0100846 if (!tg->limits_changed)
847 continue;
Vivek Goyalfe071432010-10-01 14:49:49 +0200848
Vivek Goyalde701c72011-03-07 21:09:32 +0100849 if (!xchg(&tg->limits_changed, false))
850 continue;
851
852 throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
853 " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
854 tg->iops[READ], tg->iops[WRITE]);
855
Vivek Goyal04521db2011-03-22 21:54:29 +0100856 /*
857 * Restart the slices for both READ and WRITES. It
858 * might happen that a group's limit are dropped
859 * suddenly and we don't want to account recently
860 * dispatched IO with new low rate
861 */
862 throtl_start_new_slice(td, tg, 0);
863 throtl_start_new_slice(td, tg, 1);
864
Vivek Goyalde701c72011-03-07 21:09:32 +0100865 if (throtl_tg_on_rr(tg))
866 tg_update_disptime(td, tg);
867 }
Vivek Goyalfe071432010-10-01 14:49:49 +0200868}
869
Vivek Goyale43473b2010-09-15 17:06:35 -0400870/* Dispatch throttled bios. Should be called without queue lock held. */
871static int throtl_dispatch(struct request_queue *q)
872{
873 struct throtl_data *td = q->td;
874 unsigned int nr_disp = 0;
875 struct bio_list bio_list_on_stack;
876 struct bio *bio;
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100877 struct blk_plug plug;
Vivek Goyale43473b2010-09-15 17:06:35 -0400878
879 spin_lock_irq(q->queue_lock);
880
Vivek Goyalfe071432010-10-01 14:49:49 +0200881 throtl_process_limit_change(td);
882
Vivek Goyale43473b2010-09-15 17:06:35 -0400883 if (!total_nr_queued(td))
884 goto out;
885
886 bio_list_init(&bio_list_on_stack);
887
Joe Perchesd2f31a52011-06-13 20:19:27 +0200888 throtl_log(td, "dispatch nr_queued=%u read=%u write=%u",
Vivek Goyale43473b2010-09-15 17:06:35 -0400889 total_nr_queued(td), td->nr_queued[READ],
890 td->nr_queued[WRITE]);
891
892 nr_disp = throtl_select_dispatch(td, &bio_list_on_stack);
893
894 if (nr_disp)
895 throtl_log(td, "bios disp=%u", nr_disp);
896
897 throtl_schedule_next_dispatch(td);
898out:
899 spin_unlock_irq(q->queue_lock);
900
901 /*
902 * If we dispatched some requests, unplug the queue to make sure
903 * immediate dispatch
904 */
905 if (nr_disp) {
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100906 blk_start_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400907 while((bio = bio_list_pop(&bio_list_on_stack)))
908 generic_make_request(bio);
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100909 blk_finish_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400910 }
911 return nr_disp;
912}
913
914void blk_throtl_work(struct work_struct *work)
915{
916 struct throtl_data *td = container_of(work, struct throtl_data,
917 throtl_work.work);
918 struct request_queue *q = td->queue;
919
920 throtl_dispatch(q);
921}
922
923/* Call with queue lock held */
Vivek Goyal450adcb2011-03-01 13:40:54 -0500924static void
925throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
Vivek Goyale43473b2010-09-15 17:06:35 -0400926{
927
Vivek Goyale43473b2010-09-15 17:06:35 -0400928 struct delayed_work *dwork = &td->throtl_work;
929
Vivek Goyal04521db2011-03-22 21:54:29 +0100930 /* schedule work if limits changed even if no bio is queued */
Joe Perchesd2f31a52011-06-13 20:19:27 +0200931 if (total_nr_queued(td) || td->limits_changed) {
Tejun Heoe7c2f962012-08-21 13:18:24 -0700932 mod_delayed_work(kthrotld_workqueue, dwork, delay);
Vivek Goyale43473b2010-09-15 17:06:35 -0400933 throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
934 delay, jiffies);
935 }
936}
Vivek Goyale43473b2010-09-15 17:06:35 -0400937
Tejun Heof95a04a2012-04-16 13:57:26 -0700938static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
939 struct blkg_policy_data *pd, int off)
Tejun Heo41b38b62012-04-01 14:38:44 -0700940{
Tejun Heof95a04a2012-04-16 13:57:26 -0700941 struct throtl_grp *tg = pd_to_tg(pd);
Tejun Heo41b38b62012-04-01 14:38:44 -0700942 struct blkg_rwstat rwstat = { }, tmp;
943 int i, cpu;
944
945 for_each_possible_cpu(cpu) {
Tejun Heo8a3d2612012-04-01 14:38:44 -0700946 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
Tejun Heo41b38b62012-04-01 14:38:44 -0700947
948 tmp = blkg_rwstat_read((void *)sc + off);
949 for (i = 0; i < BLKG_RWSTAT_NR; i++)
950 rwstat.cnt[i] += tmp.cnt[i];
951 }
952
Tejun Heof95a04a2012-04-16 13:57:26 -0700953 return __blkg_prfill_rwstat(sf, pd, &rwstat);
Tejun Heo41b38b62012-04-01 14:38:44 -0700954}
955
Tejun Heo8a3d2612012-04-01 14:38:44 -0700956static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
957 struct seq_file *sf)
Tejun Heo41b38b62012-04-01 14:38:44 -0700958{
Tejun Heo3c798392012-04-16 13:57:25 -0700959 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
Tejun Heo41b38b62012-04-01 14:38:44 -0700960
Tejun Heo3c798392012-04-16 13:57:25 -0700961 blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl,
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700962 cft->private, true);
Tejun Heo41b38b62012-04-01 14:38:44 -0700963 return 0;
964}
965
Tejun Heof95a04a2012-04-16 13:57:26 -0700966static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
967 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700968{
Tejun Heof95a04a2012-04-16 13:57:26 -0700969 struct throtl_grp *tg = pd_to_tg(pd);
970 u64 v = *(u64 *)((void *)tg + off);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700971
Tejun Heoaf133ce2012-04-01 14:38:44 -0700972 if (v == -1)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700973 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -0700974 return __blkg_prfill_u64(sf, pd, v);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700975}
976
Tejun Heof95a04a2012-04-16 13:57:26 -0700977static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
978 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700979{
Tejun Heof95a04a2012-04-16 13:57:26 -0700980 struct throtl_grp *tg = pd_to_tg(pd);
981 unsigned int v = *(unsigned int *)((void *)tg + off);
Tejun Heoaf133ce2012-04-01 14:38:44 -0700982
983 if (v == -1)
984 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -0700985 return __blkg_prfill_u64(sf, pd, v);
Tejun Heoaf133ce2012-04-01 14:38:44 -0700986}
987
988static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft,
989 struct seq_file *sf)
990{
Tejun Heo3c798392012-04-16 13:57:25 -0700991 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64,
992 &blkcg_policy_throtl, cft->private, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700993 return 0;
994}
995
Tejun Heoaf133ce2012-04-01 14:38:44 -0700996static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft,
997 struct seq_file *sf)
Vivek Goyale43473b2010-09-15 17:06:35 -0400998{
Tejun Heo3c798392012-04-16 13:57:25 -0700999 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint,
1000 &blkcg_policy_throtl, cft->private, false);
Tejun Heoaf133ce2012-04-01 14:38:44 -07001001 return 0;
Vivek Goyale43473b2010-09-15 17:06:35 -04001002}
1003
Tejun Heoaf133ce2012-04-01 14:38:44 -07001004static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf,
1005 bool is_u64)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001006{
Tejun Heo3c798392012-04-16 13:57:25 -07001007 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001008 struct blkg_conf_ctx ctx;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001009 struct throtl_grp *tg;
Tejun Heoa2b16932012-04-13 13:11:33 -07001010 struct throtl_data *td;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001011 int ret;
1012
Tejun Heo3c798392012-04-16 13:57:25 -07001013 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001014 if (ret)
1015 return ret;
1016
Tejun Heoaf133ce2012-04-01 14:38:44 -07001017 tg = blkg_to_tg(ctx.blkg);
Tejun Heoa2b16932012-04-13 13:11:33 -07001018 td = ctx.blkg->q->td;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001019
Tejun Heoa2b16932012-04-13 13:11:33 -07001020 if (!ctx.v)
1021 ctx.v = -1;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001022
Tejun Heoa2b16932012-04-13 13:11:33 -07001023 if (is_u64)
1024 *(u64 *)((void *)tg + cft->private) = ctx.v;
1025 else
1026 *(unsigned int *)((void *)tg + cft->private) = ctx.v;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001027
Tejun Heoa2b16932012-04-13 13:11:33 -07001028 /* XXX: we don't need the following deferred processing */
1029 xchg(&tg->limits_changed, true);
1030 xchg(&td->limits_changed, true);
1031 throtl_schedule_delayed_work(td, 0);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001032
1033 blkg_conf_finish(&ctx);
Tejun Heoa2b16932012-04-13 13:11:33 -07001034 return 0;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001035}
1036
Tejun Heoaf133ce2012-04-01 14:38:44 -07001037static int tg_set_conf_u64(struct cgroup *cgrp, struct cftype *cft,
1038 const char *buf)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001039{
Tejun Heoaf133ce2012-04-01 14:38:44 -07001040 return tg_set_conf(cgrp, cft, buf, true);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001041}
1042
Tejun Heoaf133ce2012-04-01 14:38:44 -07001043static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft,
1044 const char *buf)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001045{
Tejun Heoaf133ce2012-04-01 14:38:44 -07001046 return tg_set_conf(cgrp, cft, buf, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001047}
1048
1049static struct cftype throtl_files[] = {
1050 {
1051 .name = "throttle.read_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001052 .private = offsetof(struct throtl_grp, bps[READ]),
1053 .read_seq_string = tg_print_conf_u64,
1054 .write_string = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001055 .max_write_len = 256,
1056 },
1057 {
1058 .name = "throttle.write_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001059 .private = offsetof(struct throtl_grp, bps[WRITE]),
1060 .read_seq_string = tg_print_conf_u64,
1061 .write_string = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001062 .max_write_len = 256,
1063 },
1064 {
1065 .name = "throttle.read_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001066 .private = offsetof(struct throtl_grp, iops[READ]),
1067 .read_seq_string = tg_print_conf_uint,
1068 .write_string = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001069 .max_write_len = 256,
1070 },
1071 {
1072 .name = "throttle.write_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001073 .private = offsetof(struct throtl_grp, iops[WRITE]),
1074 .read_seq_string = tg_print_conf_uint,
1075 .write_string = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001076 .max_write_len = 256,
1077 },
1078 {
1079 .name = "throttle.io_service_bytes",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001080 .private = offsetof(struct tg_stats_cpu, service_bytes),
Tejun Heo8a3d2612012-04-01 14:38:44 -07001081 .read_seq_string = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001082 },
1083 {
1084 .name = "throttle.io_serviced",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001085 .private = offsetof(struct tg_stats_cpu, serviced),
Tejun Heo8a3d2612012-04-01 14:38:44 -07001086 .read_seq_string = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001087 },
1088 { } /* terminate */
1089};
1090
Vivek Goyalda527772011-03-02 19:05:33 -05001091static void throtl_shutdown_wq(struct request_queue *q)
Vivek Goyale43473b2010-09-15 17:06:35 -04001092{
1093 struct throtl_data *td = q->td;
1094
1095 cancel_delayed_work_sync(&td->throtl_work);
1096}
1097
Tejun Heo3c798392012-04-16 13:57:25 -07001098static struct blkcg_policy blkcg_policy_throtl = {
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001099 .pd_size = sizeof(struct throtl_grp),
1100 .cftypes = throtl_files,
1101
1102 .pd_init_fn = throtl_pd_init,
1103 .pd_exit_fn = throtl_pd_exit,
1104 .pd_reset_stats_fn = throtl_pd_reset_stats,
Vivek Goyale43473b2010-09-15 17:06:35 -04001105};
1106
Tejun Heobc16a4f2011-10-19 14:33:01 +02001107bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
Vivek Goyale43473b2010-09-15 17:06:35 -04001108{
1109 struct throtl_data *td = q->td;
1110 struct throtl_grp *tg;
Vivek Goyale43473b2010-09-15 17:06:35 -04001111 bool rw = bio_data_dir(bio), update_disptime = true;
Tejun Heo3c798392012-04-16 13:57:25 -07001112 struct blkcg *blkcg;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001113 bool throttled = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001114
1115 if (bio->bi_rw & REQ_THROTTLED) {
1116 bio->bi_rw &= ~REQ_THROTTLED;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001117 goto out;
Vivek Goyale43473b2010-09-15 17:06:35 -04001118 }
1119
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001120 /*
1121 * A throtl_grp pointer retrieved under rcu can be used to access
1122 * basic fields like stats and io rates. If a group has no rules,
1123 * just update the dispatch stats in lockless manner and return.
1124 */
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001125 rcu_read_lock();
Tejun Heo3c798392012-04-16 13:57:25 -07001126 blkcg = bio_blkcg(bio);
Tejun Heocd1604f2012-03-05 13:15:06 -08001127 tg = throtl_lookup_tg(td, blkcg);
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001128 if (tg) {
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001129 if (tg_no_rule_group(tg, rw)) {
Tejun Heo629ed0b2012-04-01 14:38:44 -07001130 throtl_update_dispatch_stats(tg_to_blkg(tg),
1131 bio->bi_size, bio->bi_rw);
Tejun Heo2a7f1242012-03-05 13:15:01 -08001132 goto out_unlock_rcu;
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001133 }
1134 }
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001135
1136 /*
1137 * Either group has not been allocated yet or it is not an unlimited
1138 * IO group
1139 */
Vivek Goyale43473b2010-09-15 17:06:35 -04001140 spin_lock_irq(q->queue_lock);
Tejun Heocd1604f2012-03-05 13:15:06 -08001141 tg = throtl_lookup_create_tg(td, blkcg);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001142 if (unlikely(!tg))
1143 goto out_unlock;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001144
Vivek Goyale43473b2010-09-15 17:06:35 -04001145 if (tg->nr_queued[rw]) {
1146 /*
1147 * There is already another bio queued in same dir. No
1148 * need to update dispatch time.
1149 */
Vivek Goyal231d7042011-03-07 21:05:14 +01001150 update_disptime = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001151 goto queue_bio;
Vivek Goyalde701c72011-03-07 21:09:32 +01001152
Vivek Goyale43473b2010-09-15 17:06:35 -04001153 }
1154
1155 /* Bio is with-in rate limit of group */
1156 if (tg_may_dispatch(td, tg, bio, NULL)) {
1157 throtl_charge_bio(tg, bio);
Vivek Goyal04521db2011-03-22 21:54:29 +01001158
1159 /*
1160 * We need to trim slice even when bios are not being queued
1161 * otherwise it might happen that a bio is not queued for
1162 * a long time and slice keeps on extending and trim is not
1163 * called for a long time. Now if limits are reduced suddenly
1164 * we take into account all the IO dispatched so far at new
1165 * low rate and * newly queued IO gets a really long dispatch
1166 * time.
1167 *
1168 * So keep on trimming slice even if bio is not queued.
1169 */
1170 throtl_trim_slice(td, tg, rw);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001171 goto out_unlock;
Vivek Goyale43473b2010-09-15 17:06:35 -04001172 }
1173
1174queue_bio:
Joe Perchesfd16d262011-06-13 10:42:49 +02001175 throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
Vivek Goyal8e89d132010-09-15 17:06:37 -04001176 " iodisp=%u iops=%u queued=%d/%d",
1177 rw == READ ? 'R' : 'W',
Vivek Goyale43473b2010-09-15 17:06:35 -04001178 tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
Vivek Goyal8e89d132010-09-15 17:06:37 -04001179 tg->io_disp[rw], tg->iops[rw],
Vivek Goyale43473b2010-09-15 17:06:35 -04001180 tg->nr_queued[READ], tg->nr_queued[WRITE]);
1181
Tejun Heo671058f2012-03-05 13:15:29 -08001182 bio_associate_current(bio);
Vivek Goyale43473b2010-09-15 17:06:35 -04001183 throtl_add_bio_tg(q->td, tg, bio);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001184 throttled = true;
Vivek Goyale43473b2010-09-15 17:06:35 -04001185
1186 if (update_disptime) {
1187 tg_update_disptime(td, tg);
1188 throtl_schedule_next_dispatch(td);
1189 }
1190
Tejun Heobc16a4f2011-10-19 14:33:01 +02001191out_unlock:
Vivek Goyale43473b2010-09-15 17:06:35 -04001192 spin_unlock_irq(q->queue_lock);
Tejun Heo2a7f1242012-03-05 13:15:01 -08001193out_unlock_rcu:
1194 rcu_read_unlock();
Tejun Heobc16a4f2011-10-19 14:33:01 +02001195out:
1196 return throttled;
Vivek Goyale43473b2010-09-15 17:06:35 -04001197}
1198
Tejun Heoc9a929d2011-10-19 14:42:16 +02001199/**
1200 * blk_throtl_drain - drain throttled bios
1201 * @q: request_queue to drain throttled bios for
1202 *
1203 * Dispatch all currently throttled bios on @q through ->make_request_fn().
1204 */
1205void blk_throtl_drain(struct request_queue *q)
1206 __releases(q->queue_lock) __acquires(q->queue_lock)
1207{
1208 struct throtl_data *td = q->td;
1209 struct throtl_rb_root *st = &td->tg_service_tree;
1210 struct throtl_grp *tg;
1211 struct bio_list bl;
1212 struct bio *bio;
1213
Andi Kleen8bcb6c72012-03-30 12:33:28 +02001214 queue_lockdep_assert_held(q);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001215
1216 bio_list_init(&bl);
1217
1218 while ((tg = throtl_rb_first(st))) {
1219 throtl_dequeue_tg(td, tg);
1220
1221 while ((bio = bio_list_peek(&tg->bio_lists[READ])))
1222 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1223 while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
1224 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1225 }
1226 spin_unlock_irq(q->queue_lock);
1227
1228 while ((bio = bio_list_pop(&bl)))
1229 generic_make_request(bio);
1230
1231 spin_lock_irq(q->queue_lock);
1232}
1233
Vivek Goyale43473b2010-09-15 17:06:35 -04001234int blk_throtl_init(struct request_queue *q)
1235{
1236 struct throtl_data *td;
Tejun Heoa2b16932012-04-13 13:11:33 -07001237 int ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001238
1239 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
1240 if (!td)
1241 return -ENOMEM;
1242
Vivek Goyale43473b2010-09-15 17:06:35 -04001243 td->tg_service_tree = THROTL_RB_ROOT;
Vivek Goyalde701c72011-03-07 21:09:32 +01001244 td->limits_changed = false;
Vivek Goyala29a1712011-05-19 15:38:19 -04001245 INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
Vivek Goyale43473b2010-09-15 17:06:35 -04001246
Tejun Heocd1604f2012-03-05 13:15:06 -08001247 q->td = td;
Vivek Goyal29b12582011-05-19 15:38:24 -04001248 td->queue = q;
Vivek Goyal02977e42010-10-01 14:49:48 +02001249
Tejun Heoa2b16932012-04-13 13:11:33 -07001250 /* activate policy */
Tejun Heo3c798392012-04-16 13:57:25 -07001251 ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
Tejun Heoa2b16932012-04-13 13:11:33 -07001252 if (ret)
Vivek Goyal29b12582011-05-19 15:38:24 -04001253 kfree(td);
Tejun Heoa2b16932012-04-13 13:11:33 -07001254 return ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001255}
1256
1257void blk_throtl_exit(struct request_queue *q)
1258{
Tejun Heoc875f4d2012-03-05 13:15:22 -08001259 BUG_ON(!q->td);
Vivek Goyalda527772011-03-02 19:05:33 -05001260 throtl_shutdown_wq(q);
Tejun Heo3c798392012-04-16 13:57:25 -07001261 blkcg_deactivate_policy(q, &blkcg_policy_throtl);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001262 kfree(q->td);
Vivek Goyale43473b2010-09-15 17:06:35 -04001263}
1264
1265static int __init throtl_init(void)
1266{
Vivek Goyal450adcb2011-03-01 13:40:54 -05001267 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
1268 if (!kthrotld_workqueue)
1269 panic("Failed to create kthrotld\n");
1270
Tejun Heo3c798392012-04-16 13:57:25 -07001271 return blkcg_policy_register(&blkcg_policy_throtl);
Vivek Goyale43473b2010-09-15 17:06:35 -04001272}
1273
1274module_init(throtl_init);