blob: 5eed6a76721d1d78e8105f4bbde30e41f20a66cd [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
Vivek Goyal450adcb2011-03-01 13:40:54 -050024/* A workqueue to queue throttle related work */
25static struct workqueue_struct *kthrotld_workqueue;
26static void throtl_schedule_delayed_work(struct throtl_data *td,
27 unsigned long delay);
28
Vivek Goyale43473b2010-09-15 17:06:35 -040029struct throtl_rb_root {
30 struct rb_root rb;
31 struct rb_node *left;
32 unsigned int count;
33 unsigned long min_disptime;
34};
35
36#define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
37 .count = 0, .min_disptime = 0}
38
39#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
40
41struct throtl_grp {
42 /* List of throtl groups on the request queue*/
43 struct hlist_node tg_node;
44
45 /* active throtl group service_tree member */
46 struct rb_node rb_node;
47
48 /*
49 * Dispatch time in jiffies. This is the estimated time when group
50 * will unthrottle and is ready to dispatch more bio. It is used as
51 * key to sort active groups in service tree.
52 */
53 unsigned long disptime;
54
55 struct blkio_group blkg;
56 atomic_t ref;
57 unsigned int flags;
58
59 /* Two lists for READ and WRITE */
60 struct bio_list bio_lists[2];
61
62 /* Number of queued bios on READ and WRITE lists */
63 unsigned int nr_queued[2];
64
65 /* bytes per second rate limits */
66 uint64_t bps[2];
67
Vivek Goyal8e89d132010-09-15 17:06:37 -040068 /* IOPS limits */
69 unsigned int iops[2];
70
Vivek Goyale43473b2010-09-15 17:06:35 -040071 /* Number of bytes disptached in current slice */
72 uint64_t bytes_disp[2];
Vivek Goyal8e89d132010-09-15 17:06:37 -040073 /* Number of bio's dispatched in current slice */
74 unsigned int io_disp[2];
Vivek Goyale43473b2010-09-15 17:06:35 -040075
76 /* When did we start a new slice */
77 unsigned long slice_start[2];
78 unsigned long slice_end[2];
Vivek Goyalfe071432010-10-01 14:49:49 +020079
80 /* Some throttle limits got updated for the group */
Andreas Schwab6f037932011-03-30 12:21:56 +020081 int limits_changed;
Vivek Goyal4843c692011-05-19 15:38:27 -040082
83 struct rcu_head rcu_head;
Vivek Goyale43473b2010-09-15 17:06:35 -040084};
85
86struct throtl_data
87{
88 /* List of throtl groups */
89 struct hlist_head tg_list;
90
91 /* service tree for active throtl groups */
92 struct throtl_rb_root tg_service_tree;
93
Vivek Goyal29b12582011-05-19 15:38:24 -040094 struct throtl_grp *root_tg;
Vivek Goyale43473b2010-09-15 17:06:35 -040095 struct request_queue *queue;
96
97 /* Total Number of queued bios on READ and WRITE lists */
98 unsigned int nr_queued[2];
99
100 /*
Vivek Goyal02977e42010-10-01 14:49:48 +0200101 * number of total undestroyed groups
Vivek Goyale43473b2010-09-15 17:06:35 -0400102 */
103 unsigned int nr_undestroyed_grps;
104
105 /* Work for dispatching throttled bios */
106 struct delayed_work throtl_work;
Vivek Goyalfe071432010-10-01 14:49:49 +0200107
Andreas Schwab6f037932011-03-30 12:21:56 +0200108 int limits_changed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400109};
110
111enum tg_state_flags {
112 THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
113};
114
115#define THROTL_TG_FNS(name) \
116static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
117{ \
118 (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
119} \
120static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
121{ \
122 (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
123} \
124static inline int throtl_tg_##name(const struct throtl_grp *tg) \
125{ \
126 return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
127}
128
129THROTL_TG_FNS(on_rr);
130
131#define throtl_log_tg(td, tg, fmt, args...) \
132 blk_add_trace_msg((td)->queue, "throtl %s " fmt, \
133 blkg_path(&(tg)->blkg), ##args); \
134
135#define throtl_log(td, fmt, args...) \
136 blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
137
138static inline struct throtl_grp *tg_of_blkg(struct blkio_group *blkg)
139{
140 if (blkg)
141 return container_of(blkg, struct throtl_grp, blkg);
142
143 return NULL;
144}
145
Joe Perchesd2f31a52011-06-13 20:19:27 +0200146static inline unsigned int total_nr_queued(struct throtl_data *td)
Vivek Goyale43473b2010-09-15 17:06:35 -0400147{
Joe Perchesd2f31a52011-06-13 20:19:27 +0200148 return td->nr_queued[0] + td->nr_queued[1];
Vivek Goyale43473b2010-09-15 17:06:35 -0400149}
150
151static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg)
152{
153 atomic_inc(&tg->ref);
154 return tg;
155}
156
Vivek Goyal4843c692011-05-19 15:38:27 -0400157static void throtl_free_tg(struct rcu_head *head)
158{
159 struct throtl_grp *tg;
160
161 tg = container_of(head, struct throtl_grp, rcu_head);
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400162 free_percpu(tg->blkg.stats_cpu);
Vivek Goyal4843c692011-05-19 15:38:27 -0400163 kfree(tg);
164}
165
Vivek Goyale43473b2010-09-15 17:06:35 -0400166static void throtl_put_tg(struct throtl_grp *tg)
167{
168 BUG_ON(atomic_read(&tg->ref) <= 0);
169 if (!atomic_dec_and_test(&tg->ref))
170 return;
Vivek Goyal4843c692011-05-19 15:38:27 -0400171
172 /*
173 * A group is freed in rcu manner. But having an rcu lock does not
174 * mean that one can access all the fields of blkg and assume these
175 * are valid. For example, don't try to follow throtl_data and
176 * request queue links.
177 *
178 * Having a reference to blkg under an rcu allows acess to only
179 * values local to groups like group stats and group rate limits
180 */
181 call_rcu(&tg->rcu_head, throtl_free_tg);
Vivek Goyale43473b2010-09-15 17:06:35 -0400182}
183
Vivek Goyala29a1712011-05-19 15:38:19 -0400184static void throtl_init_group(struct throtl_grp *tg)
185{
186 INIT_HLIST_NODE(&tg->tg_node);
187 RB_CLEAR_NODE(&tg->rb_node);
188 bio_list_init(&tg->bio_lists[0]);
189 bio_list_init(&tg->bio_lists[1]);
190 tg->limits_changed = false;
191
192 /* Practically unlimited BW */
193 tg->bps[0] = tg->bps[1] = -1;
194 tg->iops[0] = tg->iops[1] = -1;
195
196 /*
197 * Take the initial reference that will be released on destroy
198 * This can be thought of a joint reference by cgroup and
199 * request queue which will be dropped by either request queue
200 * exit or cgroup deletion path depending on who is exiting first.
201 */
202 atomic_set(&tg->ref, 1);
203}
204
205/* Should be called with rcu read lock held (needed for blkcg) */
206static void
207throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg)
208{
209 hlist_add_head(&tg->tg_node, &td->tg_list);
210 td->nr_undestroyed_grps++;
211}
212
Vivek Goyal269f5412011-05-19 15:38:25 -0400213static void
214__throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg)
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400215{
216 struct backing_dev_info *bdi = &td->queue->backing_dev_info;
217 unsigned int major, minor;
218
Vivek Goyal269f5412011-05-19 15:38:25 -0400219 if (!tg || tg->blkg.dev)
220 return;
221
222 /*
223 * Fill in device details for a group which might not have been
224 * filled at group creation time as queue was being instantiated
225 * and driver had not attached a device yet
226 */
227 if (bdi->dev && dev_name(bdi->dev)) {
228 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
229 tg->blkg.dev = MKDEV(major, minor);
230 }
231}
232
Vivek Goyalaf75cd32011-05-19 15:38:31 -0400233/*
234 * Should be called with without queue lock held. Here queue lock will be
235 * taken rarely. It will be taken only once during life time of a group
236 * if need be
237 */
238static void
239throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg)
240{
241 if (!tg || tg->blkg.dev)
242 return;
243
244 spin_lock_irq(td->queue->queue_lock);
245 __throtl_tg_fill_dev_details(td, tg);
246 spin_unlock_irq(td->queue->queue_lock);
247}
248
Vivek Goyal269f5412011-05-19 15:38:25 -0400249static void throtl_init_add_tg_lists(struct throtl_data *td,
250 struct throtl_grp *tg, struct blkio_cgroup *blkcg)
251{
252 __throtl_tg_fill_dev_details(td, tg);
253
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400254 /* Add group onto cgroup list */
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400255 blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td,
Vivek Goyal269f5412011-05-19 15:38:25 -0400256 tg->blkg.dev, BLKIO_POLICY_THROTL);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400257
258 tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
259 tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
260 tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev);
261 tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev);
262
263 throtl_add_group_to_td_list(td, tg);
264}
265
266/* Should be called without queue lock and outside of rcu period */
267static struct throtl_grp *throtl_alloc_tg(struct throtl_data *td)
268{
269 struct throtl_grp *tg = NULL;
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400270 int ret;
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400271
272 tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node);
273 if (!tg)
274 return NULL;
275
Vivek Goyal5624a4e2011-05-19 15:38:28 -0400276 ret = blkio_alloc_blkg_stats(&tg->blkg);
277
278 if (ret) {
279 kfree(tg);
280 return NULL;
281 }
282
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400283 throtl_init_group(tg);
284 return tg;
285}
286
287static struct
288throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400289{
Vivek Goyale43473b2010-09-15 17:06:35 -0400290 struct throtl_grp *tg = NULL;
291 void *key = td;
Vivek Goyale43473b2010-09-15 17:06:35 -0400292
293 /*
Vivek Goyalbe2c6b12011-01-19 08:25:02 -0700294 * This is the common case when there are no blkio cgroups.
295 * Avoid lookup in this case
296 */
297 if (blkcg == &blkio_root_cgroup)
Vivek Goyal29b12582011-05-19 15:38:24 -0400298 tg = td->root_tg;
Vivek Goyalbe2c6b12011-01-19 08:25:02 -0700299 else
300 tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
Vivek Goyale43473b2010-09-15 17:06:35 -0400301
Vivek Goyal269f5412011-05-19 15:38:25 -0400302 __throtl_tg_fill_dev_details(td, tg);
Vivek Goyale43473b2010-09-15 17:06:35 -0400303 return tg;
304}
305
306static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
307{
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400308 struct throtl_grp *tg = NULL, *__tg = NULL;
Vivek Goyal70087dc2011-05-16 15:24:08 +0200309 struct blkio_cgroup *blkcg;
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400310 struct request_queue *q = td->queue;
Vivek Goyale43473b2010-09-15 17:06:35 -0400311
Tejun Heoc9a929d2011-10-19 14:42:16 +0200312 /* no throttling for dead queue */
Tejun Heo34f60552011-12-14 00:33:37 +0100313 if (unlikely(blk_queue_dead(q)))
Tejun Heoc9a929d2011-10-19 14:42:16 +0200314 return NULL;
315
Vivek Goyale43473b2010-09-15 17:06:35 -0400316 rcu_read_lock();
Vivek Goyal70087dc2011-05-16 15:24:08 +0200317 blkcg = task_blkio_cgroup(current);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400318 tg = throtl_find_tg(td, blkcg);
319 if (tg) {
320 rcu_read_unlock();
321 return tg;
322 }
323
324 /*
325 * Need to allocate a group. Allocation of group also needs allocation
326 * of per cpu stats which in-turn takes a mutex() and can block. Hence
Tejun Heo315fcee2011-10-19 14:31:25 +0200327 * we need to drop rcu lock and queue_lock before we call alloc.
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400328 */
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400329 rcu_read_unlock();
330 spin_unlock_irq(q->queue_lock);
331
332 tg = throtl_alloc_tg(td);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400333
334 /* Group allocated and queue is still alive. take the lock */
335 spin_lock_irq(q->queue_lock);
336
Tejun Heobc16a4f2011-10-19 14:33:01 +0200337 /* Make sure @q is still alive */
Tejun Heo34f60552011-12-14 00:33:37 +0100338 if (unlikely(blk_queue_dead(q))) {
Tejun Heobc16a4f2011-10-19 14:33:01 +0200339 kfree(tg);
340 return NULL;
341 }
342
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400343 /*
344 * Initialize the new group. After sleeping, read the blkcg again.
345 */
346 rcu_read_lock();
347 blkcg = task_blkio_cgroup(current);
348
349 /*
350 * If some other thread already allocated the group while we were
351 * not holding queue lock, free up the group
352 */
353 __tg = throtl_find_tg(td, blkcg);
354
355 if (__tg) {
356 kfree(tg);
357 rcu_read_unlock();
358 return __tg;
359 }
360
361 /* Group allocation failed. Account the IO to root group */
362 if (!tg) {
Vivek Goyal29b12582011-05-19 15:38:24 -0400363 tg = td->root_tg;
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400364 return tg;
365 }
366
367 throtl_init_add_tg_lists(td, tg, blkcg);
Vivek Goyale43473b2010-09-15 17:06:35 -0400368 rcu_read_unlock();
369 return tg;
370}
371
372static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
373{
374 /* Service tree is empty */
375 if (!root->count)
376 return NULL;
377
378 if (!root->left)
379 root->left = rb_first(&root->rb);
380
381 if (root->left)
382 return rb_entry_tg(root->left);
383
384 return NULL;
385}
386
387static void rb_erase_init(struct rb_node *n, struct rb_root *root)
388{
389 rb_erase(n, root);
390 RB_CLEAR_NODE(n);
391}
392
393static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root)
394{
395 if (root->left == n)
396 root->left = NULL;
397 rb_erase_init(n, &root->rb);
398 --root->count;
399}
400
401static void update_min_dispatch_time(struct throtl_rb_root *st)
402{
403 struct throtl_grp *tg;
404
405 tg = throtl_rb_first(st);
406 if (!tg)
407 return;
408
409 st->min_disptime = tg->disptime;
410}
411
412static void
413tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
414{
415 struct rb_node **node = &st->rb.rb_node;
416 struct rb_node *parent = NULL;
417 struct throtl_grp *__tg;
418 unsigned long key = tg->disptime;
419 int left = 1;
420
421 while (*node != NULL) {
422 parent = *node;
423 __tg = rb_entry_tg(parent);
424
425 if (time_before(key, __tg->disptime))
426 node = &parent->rb_left;
427 else {
428 node = &parent->rb_right;
429 left = 0;
430 }
431 }
432
433 if (left)
434 st->left = &tg->rb_node;
435
436 rb_link_node(&tg->rb_node, parent, node);
437 rb_insert_color(&tg->rb_node, &st->rb);
438}
439
440static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
441{
442 struct throtl_rb_root *st = &td->tg_service_tree;
443
444 tg_service_tree_add(st, tg);
445 throtl_mark_tg_on_rr(tg);
446 st->count++;
447}
448
449static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
450{
451 if (!throtl_tg_on_rr(tg))
452 __throtl_enqueue_tg(td, tg);
453}
454
455static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
456{
457 throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
458 throtl_clear_tg_on_rr(tg);
459}
460
461static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
462{
463 if (throtl_tg_on_rr(tg))
464 __throtl_dequeue_tg(td, tg);
465}
466
467static void throtl_schedule_next_dispatch(struct throtl_data *td)
468{
469 struct throtl_rb_root *st = &td->tg_service_tree;
470
471 /*
472 * If there are more bios pending, schedule more work.
473 */
474 if (!total_nr_queued(td))
475 return;
476
477 BUG_ON(!st->count);
478
479 update_min_dispatch_time(st);
480
481 if (time_before_eq(st->min_disptime, jiffies))
Vivek Goyal450adcb2011-03-01 13:40:54 -0500482 throtl_schedule_delayed_work(td, 0);
Vivek Goyale43473b2010-09-15 17:06:35 -0400483 else
Vivek Goyal450adcb2011-03-01 13:40:54 -0500484 throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
Vivek Goyale43473b2010-09-15 17:06:35 -0400485}
486
487static inline void
488throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
489{
490 tg->bytes_disp[rw] = 0;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400491 tg->io_disp[rw] = 0;
Vivek Goyale43473b2010-09-15 17:06:35 -0400492 tg->slice_start[rw] = jiffies;
493 tg->slice_end[rw] = jiffies + throtl_slice;
494 throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
495 rw == READ ? 'R' : 'W', tg->slice_start[rw],
496 tg->slice_end[rw], jiffies);
497}
498
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100499static inline void throtl_set_slice_end(struct throtl_data *td,
500 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
501{
502 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
503}
504
Vivek Goyale43473b2010-09-15 17:06:35 -0400505static inline void throtl_extend_slice(struct throtl_data *td,
506 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
507{
508 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
509 throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
510 rw == READ ? 'R' : 'W', tg->slice_start[rw],
511 tg->slice_end[rw], jiffies);
512}
513
514/* Determine if previously allocated or extended slice is complete or not */
515static bool
516throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
517{
518 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
519 return 0;
520
521 return 1;
522}
523
524/* Trim the used slices and adjust slice start accordingly */
525static inline void
526throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
527{
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200528 unsigned long nr_slices, time_elapsed, io_trim;
529 u64 bytes_trim, tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400530
531 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
532
533 /*
534 * If bps are unlimited (-1), then time slice don't get
535 * renewed. Don't try to trim the slice if slice is used. A new
536 * slice will start when appropriate.
537 */
538 if (throtl_slice_used(td, tg, rw))
539 return;
540
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100541 /*
542 * A bio has been dispatched. Also adjust slice_end. It might happen
543 * that initially cgroup limit was very low resulting in high
544 * slice_end, but later limit was bumped up and bio was dispached
545 * sooner, then we need to reduce slice_end. A high bogus slice_end
546 * is bad because it does not allow new slice to start.
547 */
548
549 throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
550
Vivek Goyale43473b2010-09-15 17:06:35 -0400551 time_elapsed = jiffies - tg->slice_start[rw];
552
553 nr_slices = time_elapsed / throtl_slice;
554
555 if (!nr_slices)
556 return;
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200557 tmp = tg->bps[rw] * throtl_slice * nr_slices;
558 do_div(tmp, HZ);
559 bytes_trim = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400560
Vivek Goyal8e89d132010-09-15 17:06:37 -0400561 io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
Vivek Goyale43473b2010-09-15 17:06:35 -0400562
Vivek Goyal8e89d132010-09-15 17:06:37 -0400563 if (!bytes_trim && !io_trim)
Vivek Goyale43473b2010-09-15 17:06:35 -0400564 return;
565
566 if (tg->bytes_disp[rw] >= bytes_trim)
567 tg->bytes_disp[rw] -= bytes_trim;
568 else
569 tg->bytes_disp[rw] = 0;
570
Vivek Goyal8e89d132010-09-15 17:06:37 -0400571 if (tg->io_disp[rw] >= io_trim)
572 tg->io_disp[rw] -= io_trim;
573 else
574 tg->io_disp[rw] = 0;
575
Vivek Goyale43473b2010-09-15 17:06:35 -0400576 tg->slice_start[rw] += nr_slices * throtl_slice;
577
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200578 throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
Vivek Goyale43473b2010-09-15 17:06:35 -0400579 " start=%lu end=%lu jiffies=%lu",
Vivek Goyal8e89d132010-09-15 17:06:37 -0400580 rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
Vivek Goyale43473b2010-09-15 17:06:35 -0400581 tg->slice_start[rw], tg->slice_end[rw], jiffies);
582}
583
Vivek Goyal8e89d132010-09-15 17:06:37 -0400584static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
585 struct bio *bio, unsigned long *wait)
Vivek Goyale43473b2010-09-15 17:06:35 -0400586{
587 bool rw = bio_data_dir(bio);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400588 unsigned int io_allowed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400589 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200590 u64 tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400591
Vivek Goyal8e89d132010-09-15 17:06:37 -0400592 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
Vivek Goyale43473b2010-09-15 17:06:35 -0400593
Vivek Goyal8e89d132010-09-15 17:06:37 -0400594 /* Slice has just started. Consider one slice interval */
595 if (!jiffy_elapsed)
596 jiffy_elapsed_rnd = throtl_slice;
597
598 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
599
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200600 /*
601 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
602 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
603 * will allow dispatch after 1 second and after that slice should
604 * have been trimmed.
605 */
606
607 tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
608 do_div(tmp, HZ);
609
610 if (tmp > UINT_MAX)
611 io_allowed = UINT_MAX;
612 else
613 io_allowed = tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400614
615 if (tg->io_disp[rw] + 1 <= io_allowed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400616 if (wait)
617 *wait = 0;
618 return 1;
619 }
620
Vivek Goyal8e89d132010-09-15 17:06:37 -0400621 /* Calc approx time to dispatch */
622 jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
623
624 if (jiffy_wait > jiffy_elapsed)
625 jiffy_wait = jiffy_wait - jiffy_elapsed;
626 else
627 jiffy_wait = 1;
628
629 if (wait)
630 *wait = jiffy_wait;
631 return 0;
632}
633
634static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
635 struct bio *bio, unsigned long *wait)
636{
637 bool rw = bio_data_dir(bio);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200638 u64 bytes_allowed, extra_bytes, tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400639 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyale43473b2010-09-15 17:06:35 -0400640
641 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
642
643 /* Slice has just started. Consider one slice interval */
644 if (!jiffy_elapsed)
645 jiffy_elapsed_rnd = throtl_slice;
646
647 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
648
Vivek Goyal5e901a22010-10-01 21:16:38 +0200649 tmp = tg->bps[rw] * jiffy_elapsed_rnd;
650 do_div(tmp, HZ);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200651 bytes_allowed = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400652
653 if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
654 if (wait)
655 *wait = 0;
656 return 1;
657 }
658
659 /* Calc approx time to dispatch */
660 extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
661 jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
662
663 if (!jiffy_wait)
664 jiffy_wait = 1;
665
666 /*
667 * This wait time is without taking into consideration the rounding
668 * up we did. Add that time also.
669 */
670 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
Vivek Goyale43473b2010-09-15 17:06:35 -0400671 if (wait)
672 *wait = jiffy_wait;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400673 return 0;
674}
Vivek Goyale43473b2010-09-15 17:06:35 -0400675
Vivek Goyalaf75cd32011-05-19 15:38:31 -0400676static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
677 if (tg->bps[rw] == -1 && tg->iops[rw] == -1)
678 return 1;
679 return 0;
680}
681
Vivek Goyal8e89d132010-09-15 17:06:37 -0400682/*
683 * Returns whether one can dispatch a bio or not. Also returns approx number
684 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
685 */
686static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
687 struct bio *bio, unsigned long *wait)
688{
689 bool rw = bio_data_dir(bio);
690 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
691
692 /*
693 * Currently whole state machine of group depends on first bio
694 * queued in the group bio list. So one should not be calling
695 * this function with a different bio if there are other bios
696 * queued.
697 */
698 BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
699
700 /* If tg->bps = -1, then BW is unlimited */
701 if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
702 if (wait)
703 *wait = 0;
704 return 1;
705 }
706
707 /*
708 * If previous slice expired, start a new one otherwise renew/extend
709 * existing slice to make sure it is at least throtl_slice interval
710 * long since now.
711 */
712 if (throtl_slice_used(td, tg, rw))
713 throtl_start_new_slice(td, tg, rw);
714 else {
715 if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
716 throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
717 }
718
719 if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
720 && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
721 if (wait)
722 *wait = 0;
723 return 1;
724 }
725
726 max_wait = max(bps_wait, iops_wait);
727
728 if (wait)
729 *wait = max_wait;
730
731 if (time_before(tg->slice_end[rw], jiffies + max_wait))
732 throtl_extend_slice(td, tg, rw, jiffies + max_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -0400733
734 return 0;
735}
736
737static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
738{
739 bool rw = bio_data_dir(bio);
Shaohua Lie5a94f52011-08-01 10:31:06 +0200740 bool sync = rw_is_sync(bio->bi_rw);
Vivek Goyale43473b2010-09-15 17:06:35 -0400741
742 /* Charge the bio to the group */
743 tg->bytes_disp[rw] += bio->bi_size;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400744 tg->io_disp[rw]++;
Vivek Goyale43473b2010-09-15 17:06:35 -0400745
Vivek Goyale43473b2010-09-15 17:06:35 -0400746 blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync);
Vivek Goyale43473b2010-09-15 17:06:35 -0400747}
748
749static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
750 struct bio *bio)
751{
752 bool rw = bio_data_dir(bio);
753
754 bio_list_add(&tg->bio_lists[rw], bio);
755 /* Take a bio reference on tg */
756 throtl_ref_get_tg(tg);
757 tg->nr_queued[rw]++;
758 td->nr_queued[rw]++;
759 throtl_enqueue_tg(td, tg);
760}
761
762static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
763{
764 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
765 struct bio *bio;
766
767 if ((bio = bio_list_peek(&tg->bio_lists[READ])))
768 tg_may_dispatch(td, tg, bio, &read_wait);
769
770 if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
771 tg_may_dispatch(td, tg, bio, &write_wait);
772
773 min_wait = min(read_wait, write_wait);
774 disptime = jiffies + min_wait;
775
Vivek Goyale43473b2010-09-15 17:06:35 -0400776 /* Update dispatch time */
777 throtl_dequeue_tg(td, tg);
778 tg->disptime = disptime;
779 throtl_enqueue_tg(td, tg);
780}
781
782static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
783 bool rw, struct bio_list *bl)
784{
785 struct bio *bio;
786
787 bio = bio_list_pop(&tg->bio_lists[rw]);
788 tg->nr_queued[rw]--;
789 /* Drop bio reference on tg */
790 throtl_put_tg(tg);
791
792 BUG_ON(td->nr_queued[rw] <= 0);
793 td->nr_queued[rw]--;
794
795 throtl_charge_bio(tg, bio);
796 bio_list_add(bl, bio);
797 bio->bi_rw |= REQ_THROTTLED;
798
799 throtl_trim_slice(td, tg, rw);
800}
801
802static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
803 struct bio_list *bl)
804{
805 unsigned int nr_reads = 0, nr_writes = 0;
806 unsigned int max_nr_reads = throtl_grp_quantum*3/4;
Vivek Goyalc2f68052010-11-15 19:32:42 +0100807 unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
Vivek Goyale43473b2010-09-15 17:06:35 -0400808 struct bio *bio;
809
810 /* Try to dispatch 75% READS and 25% WRITES */
811
812 while ((bio = bio_list_peek(&tg->bio_lists[READ]))
813 && tg_may_dispatch(td, tg, bio, NULL)) {
814
815 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
816 nr_reads++;
817
818 if (nr_reads >= max_nr_reads)
819 break;
820 }
821
822 while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
823 && tg_may_dispatch(td, tg, bio, NULL)) {
824
825 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
826 nr_writes++;
827
828 if (nr_writes >= max_nr_writes)
829 break;
830 }
831
832 return nr_reads + nr_writes;
833}
834
835static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl)
836{
837 unsigned int nr_disp = 0;
838 struct throtl_grp *tg;
839 struct throtl_rb_root *st = &td->tg_service_tree;
840
841 while (1) {
842 tg = throtl_rb_first(st);
843
844 if (!tg)
845 break;
846
847 if (time_before(jiffies, tg->disptime))
848 break;
849
850 throtl_dequeue_tg(td, tg);
851
852 nr_disp += throtl_dispatch_tg(td, tg, bl);
853
854 if (tg->nr_queued[0] || tg->nr_queued[1]) {
855 tg_update_disptime(td, tg);
856 throtl_enqueue_tg(td, tg);
857 }
858
859 if (nr_disp >= throtl_quantum)
860 break;
861 }
862
863 return nr_disp;
864}
865
Vivek Goyalfe071432010-10-01 14:49:49 +0200866static void throtl_process_limit_change(struct throtl_data *td)
867{
868 struct throtl_grp *tg;
869 struct hlist_node *pos, *n;
870
Vivek Goyalde701c72011-03-07 21:09:32 +0100871 if (!td->limits_changed)
Vivek Goyalfe071432010-10-01 14:49:49 +0200872 return;
873
Vivek Goyalde701c72011-03-07 21:09:32 +0100874 xchg(&td->limits_changed, false);
Vivek Goyalfe071432010-10-01 14:49:49 +0200875
Vivek Goyalde701c72011-03-07 21:09:32 +0100876 throtl_log(td, "limits changed");
Vivek Goyalfe071432010-10-01 14:49:49 +0200877
Vivek Goyal04a6b512010-12-01 19:34:52 +0100878 hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
Vivek Goyalde701c72011-03-07 21:09:32 +0100879 if (!tg->limits_changed)
880 continue;
Vivek Goyalfe071432010-10-01 14:49:49 +0200881
Vivek Goyalde701c72011-03-07 21:09:32 +0100882 if (!xchg(&tg->limits_changed, false))
883 continue;
884
885 throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
886 " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
887 tg->iops[READ], tg->iops[WRITE]);
888
Vivek Goyal04521db2011-03-22 21:54:29 +0100889 /*
890 * Restart the slices for both READ and WRITES. It
891 * might happen that a group's limit are dropped
892 * suddenly and we don't want to account recently
893 * dispatched IO with new low rate
894 */
895 throtl_start_new_slice(td, tg, 0);
896 throtl_start_new_slice(td, tg, 1);
897
Vivek Goyalde701c72011-03-07 21:09:32 +0100898 if (throtl_tg_on_rr(tg))
899 tg_update_disptime(td, tg);
900 }
Vivek Goyalfe071432010-10-01 14:49:49 +0200901}
902
Vivek Goyale43473b2010-09-15 17:06:35 -0400903/* Dispatch throttled bios. Should be called without queue lock held. */
904static int throtl_dispatch(struct request_queue *q)
905{
906 struct throtl_data *td = q->td;
907 unsigned int nr_disp = 0;
908 struct bio_list bio_list_on_stack;
909 struct bio *bio;
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100910 struct blk_plug plug;
Vivek Goyale43473b2010-09-15 17:06:35 -0400911
912 spin_lock_irq(q->queue_lock);
913
Vivek Goyalfe071432010-10-01 14:49:49 +0200914 throtl_process_limit_change(td);
915
Vivek Goyale43473b2010-09-15 17:06:35 -0400916 if (!total_nr_queued(td))
917 goto out;
918
919 bio_list_init(&bio_list_on_stack);
920
Joe Perchesd2f31a52011-06-13 20:19:27 +0200921 throtl_log(td, "dispatch nr_queued=%u read=%u write=%u",
Vivek Goyale43473b2010-09-15 17:06:35 -0400922 total_nr_queued(td), td->nr_queued[READ],
923 td->nr_queued[WRITE]);
924
925 nr_disp = throtl_select_dispatch(td, &bio_list_on_stack);
926
927 if (nr_disp)
928 throtl_log(td, "bios disp=%u", nr_disp);
929
930 throtl_schedule_next_dispatch(td);
931out:
932 spin_unlock_irq(q->queue_lock);
933
934 /*
935 * If we dispatched some requests, unplug the queue to make sure
936 * immediate dispatch
937 */
938 if (nr_disp) {
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100939 blk_start_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400940 while((bio = bio_list_pop(&bio_list_on_stack)))
941 generic_make_request(bio);
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100942 blk_finish_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400943 }
944 return nr_disp;
945}
946
947void blk_throtl_work(struct work_struct *work)
948{
949 struct throtl_data *td = container_of(work, struct throtl_data,
950 throtl_work.work);
951 struct request_queue *q = td->queue;
952
953 throtl_dispatch(q);
954}
955
956/* Call with queue lock held */
Vivek Goyal450adcb2011-03-01 13:40:54 -0500957static void
958throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
Vivek Goyale43473b2010-09-15 17:06:35 -0400959{
960
Vivek Goyale43473b2010-09-15 17:06:35 -0400961 struct delayed_work *dwork = &td->throtl_work;
962
Vivek Goyal04521db2011-03-22 21:54:29 +0100963 /* schedule work if limits changed even if no bio is queued */
Joe Perchesd2f31a52011-06-13 20:19:27 +0200964 if (total_nr_queued(td) || td->limits_changed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400965 /*
966 * We might have a work scheduled to be executed in future.
967 * Cancel that and schedule a new one.
968 */
969 __cancel_delayed_work(dwork);
Vivek Goyal450adcb2011-03-01 13:40:54 -0500970 queue_delayed_work(kthrotld_workqueue, dwork, delay);
Vivek Goyale43473b2010-09-15 17:06:35 -0400971 throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
972 delay, jiffies);
973 }
974}
Vivek Goyale43473b2010-09-15 17:06:35 -0400975
976static void
977throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg)
978{
979 /* Something wrong if we are trying to remove same group twice */
980 BUG_ON(hlist_unhashed(&tg->tg_node));
981
982 hlist_del_init(&tg->tg_node);
983
984 /*
985 * Put the reference taken at the time of creation so that when all
986 * queues are gone, group can be destroyed.
987 */
988 throtl_put_tg(tg);
989 td->nr_undestroyed_grps--;
990}
991
992static void throtl_release_tgs(struct throtl_data *td)
993{
994 struct hlist_node *pos, *n;
995 struct throtl_grp *tg;
996
997 hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
998 /*
999 * If cgroup removal path got to blk_group first and removed
1000 * it from cgroup list, then it will take care of destroying
1001 * cfqg also.
1002 */
1003 if (!blkiocg_del_blkio_group(&tg->blkg))
1004 throtl_destroy_tg(td, tg);
1005 }
1006}
1007
Vivek Goyale43473b2010-09-15 17:06:35 -04001008/*
1009 * Blk cgroup controller notification saying that blkio_group object is being
1010 * delinked as associated cgroup object is going away. That also means that
1011 * no new IO will come in this group. So get rid of this group as soon as
1012 * any pending IO in the group is finished.
1013 *
1014 * This function is called under rcu_read_lock(). key is the rcu protected
1015 * pointer. That means "key" is a valid throtl_data pointer as long as we are
1016 * rcu read lock.
1017 *
1018 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1019 * it should not be NULL as even if queue was going away, cgroup deltion
1020 * path got to it first.
1021 */
1022void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg)
1023{
1024 unsigned long flags;
1025 struct throtl_data *td = key;
1026
1027 spin_lock_irqsave(td->queue->queue_lock, flags);
1028 throtl_destroy_tg(td, tg_of_blkg(blkg));
1029 spin_unlock_irqrestore(td->queue->queue_lock, flags);
1030}
1031
Vivek Goyalde701c72011-03-07 21:09:32 +01001032static void throtl_update_blkio_group_common(struct throtl_data *td,
1033 struct throtl_grp *tg)
1034{
1035 xchg(&tg->limits_changed, true);
1036 xchg(&td->limits_changed, true);
1037 /* Schedule a work now to process the limit change */
1038 throtl_schedule_delayed_work(td, 0);
1039}
1040
Vivek Goyalfe071432010-10-01 14:49:49 +02001041/*
1042 * For all update functions, key should be a valid pointer because these
1043 * update functions are called under blkcg_lock, that means, blkg is
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001044 * valid and in turn key is valid. queue exit path can not race because
Vivek Goyalfe071432010-10-01 14:49:49 +02001045 * of blkcg_lock
1046 *
1047 * Can not take queue lock in update functions as queue lock under blkcg_lock
1048 * is not allowed. Under other paths we take blkcg_lock under queue_lock.
1049 */
1050static void throtl_update_blkio_group_read_bps(void *key,
1051 struct blkio_group *blkg, u64 read_bps)
Vivek Goyale43473b2010-09-15 17:06:35 -04001052{
Vivek Goyalfe071432010-10-01 14:49:49 +02001053 struct throtl_data *td = key;
Vivek Goyalde701c72011-03-07 21:09:32 +01001054 struct throtl_grp *tg = tg_of_blkg(blkg);
Vivek Goyalfe071432010-10-01 14:49:49 +02001055
Vivek Goyalde701c72011-03-07 21:09:32 +01001056 tg->bps[READ] = read_bps;
1057 throtl_update_blkio_group_common(td, tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001058}
1059
Vivek Goyalfe071432010-10-01 14:49:49 +02001060static void throtl_update_blkio_group_write_bps(void *key,
1061 struct blkio_group *blkg, u64 write_bps)
Vivek Goyale43473b2010-09-15 17:06:35 -04001062{
Vivek Goyalfe071432010-10-01 14:49:49 +02001063 struct throtl_data *td = key;
Vivek Goyalde701c72011-03-07 21:09:32 +01001064 struct throtl_grp *tg = tg_of_blkg(blkg);
Vivek Goyalfe071432010-10-01 14:49:49 +02001065
Vivek Goyalde701c72011-03-07 21:09:32 +01001066 tg->bps[WRITE] = write_bps;
1067 throtl_update_blkio_group_common(td, tg);
Vivek Goyale43473b2010-09-15 17:06:35 -04001068}
1069
Vivek Goyalfe071432010-10-01 14:49:49 +02001070static void throtl_update_blkio_group_read_iops(void *key,
1071 struct blkio_group *blkg, unsigned int read_iops)
Vivek Goyal8e89d132010-09-15 17:06:37 -04001072{
Vivek Goyalfe071432010-10-01 14:49:49 +02001073 struct throtl_data *td = key;
Vivek Goyalde701c72011-03-07 21:09:32 +01001074 struct throtl_grp *tg = tg_of_blkg(blkg);
Vivek Goyalfe071432010-10-01 14:49:49 +02001075
Vivek Goyalde701c72011-03-07 21:09:32 +01001076 tg->iops[READ] = read_iops;
1077 throtl_update_blkio_group_common(td, tg);
Vivek Goyal8e89d132010-09-15 17:06:37 -04001078}
1079
Vivek Goyalfe071432010-10-01 14:49:49 +02001080static void throtl_update_blkio_group_write_iops(void *key,
1081 struct blkio_group *blkg, unsigned int write_iops)
Vivek Goyal8e89d132010-09-15 17:06:37 -04001082{
Vivek Goyalfe071432010-10-01 14:49:49 +02001083 struct throtl_data *td = key;
Vivek Goyalde701c72011-03-07 21:09:32 +01001084 struct throtl_grp *tg = tg_of_blkg(blkg);
Vivek Goyalfe071432010-10-01 14:49:49 +02001085
Vivek Goyalde701c72011-03-07 21:09:32 +01001086 tg->iops[WRITE] = write_iops;
1087 throtl_update_blkio_group_common(td, tg);
Vivek Goyal8e89d132010-09-15 17:06:37 -04001088}
1089
Vivek Goyalda527772011-03-02 19:05:33 -05001090static void throtl_shutdown_wq(struct request_queue *q)
Vivek Goyale43473b2010-09-15 17:06:35 -04001091{
1092 struct throtl_data *td = q->td;
1093
1094 cancel_delayed_work_sync(&td->throtl_work);
1095}
1096
1097static struct blkio_policy_type blkio_policy_throtl = {
1098 .ops = {
1099 .blkio_unlink_group_fn = throtl_unlink_blkio_group,
1100 .blkio_update_group_read_bps_fn =
1101 throtl_update_blkio_group_read_bps,
1102 .blkio_update_group_write_bps_fn =
1103 throtl_update_blkio_group_write_bps,
Vivek Goyal8e89d132010-09-15 17:06:37 -04001104 .blkio_update_group_read_iops_fn =
1105 throtl_update_blkio_group_read_iops,
1106 .blkio_update_group_write_iops_fn =
1107 throtl_update_blkio_group_write_iops,
Vivek Goyale43473b2010-09-15 17:06:35 -04001108 },
Vivek Goyal8e89d132010-09-15 17:06:37 -04001109 .plid = BLKIO_POLICY_THROTL,
Vivek Goyale43473b2010-09-15 17:06:35 -04001110};
1111
Tejun Heobc16a4f2011-10-19 14:33:01 +02001112bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
Vivek Goyale43473b2010-09-15 17:06:35 -04001113{
1114 struct throtl_data *td = q->td;
1115 struct throtl_grp *tg;
Vivek Goyale43473b2010-09-15 17:06:35 -04001116 bool rw = bio_data_dir(bio), update_disptime = true;
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001117 struct blkio_cgroup *blkcg;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001118 bool throttled = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001119
1120 if (bio->bi_rw & REQ_THROTTLED) {
1121 bio->bi_rw &= ~REQ_THROTTLED;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001122 goto out;
Vivek Goyale43473b2010-09-15 17:06:35 -04001123 }
1124
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001125 /*
1126 * A throtl_grp pointer retrieved under rcu can be used to access
1127 * basic fields like stats and io rates. If a group has no rules,
1128 * just update the dispatch stats in lockless manner and return.
1129 */
1130
1131 rcu_read_lock();
1132 blkcg = task_blkio_cgroup(current);
1133 tg = throtl_find_tg(td, blkcg);
1134 if (tg) {
1135 throtl_tg_fill_dev_details(td, tg);
1136
1137 if (tg_no_rule_group(tg, rw)) {
1138 blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size,
Shaohua Lie5a94f52011-08-01 10:31:06 +02001139 rw, rw_is_sync(bio->bi_rw));
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001140 rcu_read_unlock();
Tejun Heobc16a4f2011-10-19 14:33:01 +02001141 goto out;
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001142 }
1143 }
1144 rcu_read_unlock();
1145
1146 /*
1147 * Either group has not been allocated yet or it is not an unlimited
1148 * IO group
1149 */
Vivek Goyale43473b2010-09-15 17:06:35 -04001150 spin_lock_irq(q->queue_lock);
1151 tg = throtl_get_tg(td);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001152 if (unlikely(!tg))
1153 goto out_unlock;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001154
Vivek Goyale43473b2010-09-15 17:06:35 -04001155 if (tg->nr_queued[rw]) {
1156 /*
1157 * There is already another bio queued in same dir. No
1158 * need to update dispatch time.
1159 */
Vivek Goyal231d7042011-03-07 21:05:14 +01001160 update_disptime = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001161 goto queue_bio;
Vivek Goyalde701c72011-03-07 21:09:32 +01001162
Vivek Goyale43473b2010-09-15 17:06:35 -04001163 }
1164
1165 /* Bio is with-in rate limit of group */
1166 if (tg_may_dispatch(td, tg, bio, NULL)) {
1167 throtl_charge_bio(tg, bio);
Vivek Goyal04521db2011-03-22 21:54:29 +01001168
1169 /*
1170 * We need to trim slice even when bios are not being queued
1171 * otherwise it might happen that a bio is not queued for
1172 * a long time and slice keeps on extending and trim is not
1173 * called for a long time. Now if limits are reduced suddenly
1174 * we take into account all the IO dispatched so far at new
1175 * low rate and * newly queued IO gets a really long dispatch
1176 * time.
1177 *
1178 * So keep on trimming slice even if bio is not queued.
1179 */
1180 throtl_trim_slice(td, tg, rw);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001181 goto out_unlock;
Vivek Goyale43473b2010-09-15 17:06:35 -04001182 }
1183
1184queue_bio:
Joe Perchesfd16d262011-06-13 10:42:49 +02001185 throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
Vivek Goyal8e89d132010-09-15 17:06:37 -04001186 " iodisp=%u iops=%u queued=%d/%d",
1187 rw == READ ? 'R' : 'W',
Vivek Goyale43473b2010-09-15 17:06:35 -04001188 tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
Vivek Goyal8e89d132010-09-15 17:06:37 -04001189 tg->io_disp[rw], tg->iops[rw],
Vivek Goyale43473b2010-09-15 17:06:35 -04001190 tg->nr_queued[READ], tg->nr_queued[WRITE]);
1191
1192 throtl_add_bio_tg(q->td, tg, bio);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001193 throttled = true;
Vivek Goyale43473b2010-09-15 17:06:35 -04001194
1195 if (update_disptime) {
1196 tg_update_disptime(td, tg);
1197 throtl_schedule_next_dispatch(td);
1198 }
1199
Tejun Heobc16a4f2011-10-19 14:33:01 +02001200out_unlock:
Vivek Goyale43473b2010-09-15 17:06:35 -04001201 spin_unlock_irq(q->queue_lock);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001202out:
1203 return throttled;
Vivek Goyale43473b2010-09-15 17:06:35 -04001204}
1205
Tejun Heoc9a929d2011-10-19 14:42:16 +02001206/**
1207 * blk_throtl_drain - drain throttled bios
1208 * @q: request_queue to drain throttled bios for
1209 *
1210 * Dispatch all currently throttled bios on @q through ->make_request_fn().
1211 */
1212void blk_throtl_drain(struct request_queue *q)
1213 __releases(q->queue_lock) __acquires(q->queue_lock)
1214{
1215 struct throtl_data *td = q->td;
1216 struct throtl_rb_root *st = &td->tg_service_tree;
1217 struct throtl_grp *tg;
1218 struct bio_list bl;
1219 struct bio *bio;
1220
Jens Axboe334c2b02011-10-25 15:51:48 +02001221 WARN_ON_ONCE(!queue_is_locked(q));
Tejun Heoc9a929d2011-10-19 14:42:16 +02001222
1223 bio_list_init(&bl);
1224
1225 while ((tg = throtl_rb_first(st))) {
1226 throtl_dequeue_tg(td, tg);
1227
1228 while ((bio = bio_list_peek(&tg->bio_lists[READ])))
1229 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1230 while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
1231 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1232 }
1233 spin_unlock_irq(q->queue_lock);
1234
1235 while ((bio = bio_list_pop(&bl)))
1236 generic_make_request(bio);
1237
1238 spin_lock_irq(q->queue_lock);
1239}
1240
Vivek Goyale43473b2010-09-15 17:06:35 -04001241int blk_throtl_init(struct request_queue *q)
1242{
1243 struct throtl_data *td;
1244 struct throtl_grp *tg;
1245
1246 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
1247 if (!td)
1248 return -ENOMEM;
1249
1250 INIT_HLIST_HEAD(&td->tg_list);
1251 td->tg_service_tree = THROTL_RB_ROOT;
Vivek Goyalde701c72011-03-07 21:09:32 +01001252 td->limits_changed = false;
Vivek Goyala29a1712011-05-19 15:38:19 -04001253 INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
Vivek Goyale43473b2010-09-15 17:06:35 -04001254
Vivek Goyal29b12582011-05-19 15:38:24 -04001255 /* alloc and Init root group. */
1256 td->queue = q;
1257 tg = throtl_alloc_tg(td);
Vivek Goyal02977e42010-10-01 14:49:48 +02001258
Vivek Goyal29b12582011-05-19 15:38:24 -04001259 if (!tg) {
1260 kfree(td);
1261 return -ENOMEM;
1262 }
1263
1264 td->root_tg = tg;
Vivek Goyale43473b2010-09-15 17:06:35 -04001265
1266 rcu_read_lock();
Vivek Goyal5617cbe2011-05-19 15:38:26 -04001267 throtl_init_add_tg_lists(td, tg, &blkio_root_cgroup);
Vivek Goyale43473b2010-09-15 17:06:35 -04001268 rcu_read_unlock();
1269
1270 /* Attach throtl data to request queue */
Vivek Goyale43473b2010-09-15 17:06:35 -04001271 q->td = td;
1272 return 0;
1273}
1274
1275void blk_throtl_exit(struct request_queue *q)
1276{
1277 struct throtl_data *td = q->td;
1278 bool wait = false;
1279
1280 BUG_ON(!td);
1281
Vivek Goyalda527772011-03-02 19:05:33 -05001282 throtl_shutdown_wq(q);
Vivek Goyale43473b2010-09-15 17:06:35 -04001283
1284 spin_lock_irq(q->queue_lock);
1285 throtl_release_tgs(td);
Vivek Goyale43473b2010-09-15 17:06:35 -04001286
1287 /* If there are other groups */
Vivek Goyal02977e42010-10-01 14:49:48 +02001288 if (td->nr_undestroyed_grps > 0)
Vivek Goyale43473b2010-09-15 17:06:35 -04001289 wait = true;
1290
1291 spin_unlock_irq(q->queue_lock);
1292
1293 /*
1294 * Wait for tg->blkg->key accessors to exit their grace periods.
1295 * Do this wait only if there are other undestroyed groups out
1296 * there (other than root group). This can happen if cgroup deletion
1297 * path claimed the responsibility of cleaning up a group before
1298 * queue cleanup code get to the group.
1299 *
1300 * Do not call synchronize_rcu() unconditionally as there are drivers
1301 * which create/delete request queue hundreds of times during scan/boot
1302 * and synchronize_rcu() can take significant time and slow down boot.
1303 */
1304 if (wait)
1305 synchronize_rcu();
Vivek Goyalfe071432010-10-01 14:49:49 +02001306
1307 /*
1308 * Just being safe to make sure after previous flush if some body did
1309 * update limits through cgroup and another work got queued, cancel
1310 * it.
1311 */
Vivek Goyalda527772011-03-02 19:05:33 -05001312 throtl_shutdown_wq(q);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001313}
1314
1315void blk_throtl_release(struct request_queue *q)
1316{
1317 kfree(q->td);
Vivek Goyale43473b2010-09-15 17:06:35 -04001318}
1319
1320static int __init throtl_init(void)
1321{
Vivek Goyal450adcb2011-03-01 13:40:54 -05001322 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
1323 if (!kthrotld_workqueue)
1324 panic("Failed to create kthrotld\n");
1325
Vivek Goyale43473b2010-09-15 17:06:35 -04001326 blkio_policy_register(&blkio_policy_throtl);
1327 return 0;
1328}
1329
1330module_init(throtl_init);