blob: 5b0659512047208efdcc3db7d714bc72dfd456f5 [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
183 * system_nrt_wq once there are some groups on the alloc_list waiting for
184 * 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 */
197 queue_delayed_work(system_nrt_wq, dwork,
198 msecs_to_jiffies(10));
199 return;
200 }
201 }
202
203 spin_lock_irq(&tg_stats_alloc_lock);
204
205 if (!list_empty(&tg_stats_alloc_list)) {
206 struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list,
207 struct throtl_grp,
208 stats_alloc_node);
209 swap(tg->stats_cpu, stats_cpu);
210 list_del_init(&tg->stats_alloc_node);
211 }
212
213 empty = list_empty(&tg_stats_alloc_list);
214 spin_unlock_irq(&tg_stats_alloc_lock);
215 if (!empty)
216 goto alloc_stats;
217}
218
Tejun Heo3c798392012-04-16 13:57:25 -0700219static void throtl_pd_init(struct blkcg_gq *blkg)
Vivek Goyala29a1712011-05-19 15:38:19 -0400220{
Tejun Heo03814112012-03-05 13:15:14 -0800221 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200222 unsigned long flags;
Tejun Heocd1604f2012-03-05 13:15:06 -0800223
Vivek Goyala29a1712011-05-19 15:38:19 -0400224 RB_CLEAR_NODE(&tg->rb_node);
225 bio_list_init(&tg->bio_lists[0]);
226 bio_list_init(&tg->bio_lists[1]);
227 tg->limits_changed = false;
228
Tejun Heoe56da7e2012-03-05 13:15:07 -0800229 tg->bps[READ] = -1;
230 tg->bps[WRITE] = -1;
231 tg->iops[READ] = -1;
232 tg->iops[WRITE] = -1;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700233
234 /*
235 * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
236 * but percpu allocator can't be called from IO path. Queue tg on
237 * tg_stats_alloc_list and allocate from work item.
238 */
Tejun Heoff26eaa2012-05-23 12:16:21 +0200239 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700240 list_add(&tg->stats_alloc_node, &tg_stats_alloc_list);
241 queue_delayed_work(system_nrt_wq, &tg_stats_alloc_work, 0);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200242 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700243}
244
Tejun Heo3c798392012-04-16 13:57:25 -0700245static void throtl_pd_exit(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700246{
247 struct throtl_grp *tg = blkg_to_tg(blkg);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200248 unsigned long flags;
Tejun Heo8a3d2612012-04-01 14:38:44 -0700249
Tejun Heoff26eaa2012-05-23 12:16:21 +0200250 spin_lock_irqsave(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700251 list_del_init(&tg->stats_alloc_node);
Tejun Heoff26eaa2012-05-23 12:16:21 +0200252 spin_unlock_irqrestore(&tg_stats_alloc_lock, flags);
Tejun Heo8a3d2612012-04-01 14:38:44 -0700253
254 free_percpu(tg->stats_cpu);
255}
256
Tejun Heo3c798392012-04-16 13:57:25 -0700257static void throtl_pd_reset_stats(struct blkcg_gq *blkg)
Tejun Heo8a3d2612012-04-01 14:38:44 -0700258{
259 struct throtl_grp *tg = blkg_to_tg(blkg);
260 int cpu;
261
262 if (tg->stats_cpu == NULL)
263 return;
264
265 for_each_possible_cpu(cpu) {
266 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
267
268 blkg_rwstat_reset(&sc->service_bytes);
269 blkg_rwstat_reset(&sc->serviced);
270 }
Vivek Goyala29a1712011-05-19 15:38:19 -0400271}
272
Tejun Heo3c798392012-04-16 13:57:25 -0700273static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td,
274 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400275{
Vivek Goyale43473b2010-09-15 17:06:35 -0400276 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700277 * This is the common case when there are no blkcgs. Avoid lookup
278 * in this case
Tejun Heocd1604f2012-03-05 13:15:06 -0800279 */
Tejun Heo3c798392012-04-16 13:57:25 -0700280 if (blkcg == &blkcg_root)
Tejun Heo03d8e112012-04-13 13:11:32 -0700281 return td_root_tg(td);
Vivek Goyale43473b2010-09-15 17:06:35 -0400282
Tejun Heoe8989fa2012-03-05 13:15:20 -0800283 return blkg_to_tg(blkg_lookup(blkcg, td->queue));
Vivek Goyale43473b2010-09-15 17:06:35 -0400284}
285
Tejun Heocd1604f2012-03-05 13:15:06 -0800286static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
Tejun Heo3c798392012-04-16 13:57:25 -0700287 struct blkcg *blkcg)
Vivek Goyale43473b2010-09-15 17:06:35 -0400288{
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400289 struct request_queue *q = td->queue;
Tejun Heocd1604f2012-03-05 13:15:06 -0800290 struct throtl_grp *tg = NULL;
Tejun Heo0a5a7d02012-03-05 13:15:02 -0800291
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400292 /*
Tejun Heo3c798392012-04-16 13:57:25 -0700293 * This is the common case when there are no blkcgs. Avoid lookup
294 * in this case
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400295 */
Tejun Heo3c798392012-04-16 13:57:25 -0700296 if (blkcg == &blkcg_root) {
Tejun Heo03d8e112012-04-13 13:11:32 -0700297 tg = td_root_tg(td);
Tejun Heocd1604f2012-03-05 13:15:06 -0800298 } else {
Tejun Heo3c798392012-04-16 13:57:25 -0700299 struct blkcg_gq *blkg;
Tejun Heocd1604f2012-03-05 13:15:06 -0800300
Tejun Heo3c96cb32012-04-13 13:11:34 -0700301 blkg = blkg_lookup_create(blkcg, q);
Tejun Heocd1604f2012-03-05 13:15:06 -0800302
303 /* if %NULL and @q is alive, fall back to root_tg */
304 if (!IS_ERR(blkg))
Tejun Heo03814112012-03-05 13:15:14 -0800305 tg = blkg_to_tg(blkg);
Tejun Heocd1604f2012-03-05 13:15:06 -0800306 else if (!blk_queue_dead(q))
Tejun Heo03d8e112012-04-13 13:11:32 -0700307 tg = td_root_tg(td);
Vivek Goyalf469a7b2011-05-19 15:38:23 -0400308 }
309
Vivek Goyale43473b2010-09-15 17:06:35 -0400310 return tg;
311}
312
313static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
314{
315 /* Service tree is empty */
316 if (!root->count)
317 return NULL;
318
319 if (!root->left)
320 root->left = rb_first(&root->rb);
321
322 if (root->left)
323 return rb_entry_tg(root->left);
324
325 return NULL;
326}
327
328static void rb_erase_init(struct rb_node *n, struct rb_root *root)
329{
330 rb_erase(n, root);
331 RB_CLEAR_NODE(n);
332}
333
334static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root)
335{
336 if (root->left == n)
337 root->left = NULL;
338 rb_erase_init(n, &root->rb);
339 --root->count;
340}
341
342static void update_min_dispatch_time(struct throtl_rb_root *st)
343{
344 struct throtl_grp *tg;
345
346 tg = throtl_rb_first(st);
347 if (!tg)
348 return;
349
350 st->min_disptime = tg->disptime;
351}
352
353static void
354tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
355{
356 struct rb_node **node = &st->rb.rb_node;
357 struct rb_node *parent = NULL;
358 struct throtl_grp *__tg;
359 unsigned long key = tg->disptime;
360 int left = 1;
361
362 while (*node != NULL) {
363 parent = *node;
364 __tg = rb_entry_tg(parent);
365
366 if (time_before(key, __tg->disptime))
367 node = &parent->rb_left;
368 else {
369 node = &parent->rb_right;
370 left = 0;
371 }
372 }
373
374 if (left)
375 st->left = &tg->rb_node;
376
377 rb_link_node(&tg->rb_node, parent, node);
378 rb_insert_color(&tg->rb_node, &st->rb);
379}
380
381static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
382{
383 struct throtl_rb_root *st = &td->tg_service_tree;
384
385 tg_service_tree_add(st, tg);
386 throtl_mark_tg_on_rr(tg);
387 st->count++;
388}
389
390static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
391{
392 if (!throtl_tg_on_rr(tg))
393 __throtl_enqueue_tg(td, tg);
394}
395
396static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
397{
398 throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
399 throtl_clear_tg_on_rr(tg);
400}
401
402static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
403{
404 if (throtl_tg_on_rr(tg))
405 __throtl_dequeue_tg(td, tg);
406}
407
408static void throtl_schedule_next_dispatch(struct throtl_data *td)
409{
410 struct throtl_rb_root *st = &td->tg_service_tree;
411
412 /*
413 * If there are more bios pending, schedule more work.
414 */
415 if (!total_nr_queued(td))
416 return;
417
418 BUG_ON(!st->count);
419
420 update_min_dispatch_time(st);
421
422 if (time_before_eq(st->min_disptime, jiffies))
Vivek Goyal450adcb2011-03-01 13:40:54 -0500423 throtl_schedule_delayed_work(td, 0);
Vivek Goyale43473b2010-09-15 17:06:35 -0400424 else
Vivek Goyal450adcb2011-03-01 13:40:54 -0500425 throtl_schedule_delayed_work(td, (st->min_disptime - jiffies));
Vivek Goyale43473b2010-09-15 17:06:35 -0400426}
427
428static inline void
429throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
430{
431 tg->bytes_disp[rw] = 0;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400432 tg->io_disp[rw] = 0;
Vivek Goyale43473b2010-09-15 17:06:35 -0400433 tg->slice_start[rw] = jiffies;
434 tg->slice_end[rw] = jiffies + throtl_slice;
435 throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
436 rw == READ ? 'R' : 'W', tg->slice_start[rw],
437 tg->slice_end[rw], jiffies);
438}
439
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100440static inline void throtl_set_slice_end(struct throtl_data *td,
441 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
442{
443 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
444}
445
Vivek Goyale43473b2010-09-15 17:06:35 -0400446static inline void throtl_extend_slice(struct throtl_data *td,
447 struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
448{
449 tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
450 throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
451 rw == READ ? 'R' : 'W', tg->slice_start[rw],
452 tg->slice_end[rw], jiffies);
453}
454
455/* Determine if previously allocated or extended slice is complete or not */
456static bool
457throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
458{
459 if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
460 return 0;
461
462 return 1;
463}
464
465/* Trim the used slices and adjust slice start accordingly */
466static inline void
467throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
468{
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200469 unsigned long nr_slices, time_elapsed, io_trim;
470 u64 bytes_trim, tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400471
472 BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
473
474 /*
475 * If bps are unlimited (-1), then time slice don't get
476 * renewed. Don't try to trim the slice if slice is used. A new
477 * slice will start when appropriate.
478 */
479 if (throtl_slice_used(td, tg, rw))
480 return;
481
Vivek Goyald1ae8ff2010-12-01 19:34:46 +0100482 /*
483 * A bio has been dispatched. Also adjust slice_end. It might happen
484 * that initially cgroup limit was very low resulting in high
485 * slice_end, but later limit was bumped up and bio was dispached
486 * sooner, then we need to reduce slice_end. A high bogus slice_end
487 * is bad because it does not allow new slice to start.
488 */
489
490 throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
491
Vivek Goyale43473b2010-09-15 17:06:35 -0400492 time_elapsed = jiffies - tg->slice_start[rw];
493
494 nr_slices = time_elapsed / throtl_slice;
495
496 if (!nr_slices)
497 return;
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200498 tmp = tg->bps[rw] * throtl_slice * nr_slices;
499 do_div(tmp, HZ);
500 bytes_trim = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400501
Vivek Goyal8e89d132010-09-15 17:06:37 -0400502 io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
Vivek Goyale43473b2010-09-15 17:06:35 -0400503
Vivek Goyal8e89d132010-09-15 17:06:37 -0400504 if (!bytes_trim && !io_trim)
Vivek Goyale43473b2010-09-15 17:06:35 -0400505 return;
506
507 if (tg->bytes_disp[rw] >= bytes_trim)
508 tg->bytes_disp[rw] -= bytes_trim;
509 else
510 tg->bytes_disp[rw] = 0;
511
Vivek Goyal8e89d132010-09-15 17:06:37 -0400512 if (tg->io_disp[rw] >= io_trim)
513 tg->io_disp[rw] -= io_trim;
514 else
515 tg->io_disp[rw] = 0;
516
Vivek Goyale43473b2010-09-15 17:06:35 -0400517 tg->slice_start[rw] += nr_slices * throtl_slice;
518
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200519 throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
Vivek Goyale43473b2010-09-15 17:06:35 -0400520 " start=%lu end=%lu jiffies=%lu",
Vivek Goyal8e89d132010-09-15 17:06:37 -0400521 rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
Vivek Goyale43473b2010-09-15 17:06:35 -0400522 tg->slice_start[rw], tg->slice_end[rw], jiffies);
523}
524
Vivek Goyal8e89d132010-09-15 17:06:37 -0400525static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
526 struct bio *bio, unsigned long *wait)
Vivek Goyale43473b2010-09-15 17:06:35 -0400527{
528 bool rw = bio_data_dir(bio);
Vivek Goyal8e89d132010-09-15 17:06:37 -0400529 unsigned int io_allowed;
Vivek Goyale43473b2010-09-15 17:06:35 -0400530 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200531 u64 tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400532
Vivek Goyal8e89d132010-09-15 17:06:37 -0400533 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
Vivek Goyale43473b2010-09-15 17:06:35 -0400534
Vivek Goyal8e89d132010-09-15 17:06:37 -0400535 /* Slice has just started. Consider one slice interval */
536 if (!jiffy_elapsed)
537 jiffy_elapsed_rnd = throtl_slice;
538
539 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
540
Vivek Goyalc49c06e2010-10-01 21:16:42 +0200541 /*
542 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
543 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
544 * will allow dispatch after 1 second and after that slice should
545 * have been trimmed.
546 */
547
548 tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
549 do_div(tmp, HZ);
550
551 if (tmp > UINT_MAX)
552 io_allowed = UINT_MAX;
553 else
554 io_allowed = tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400555
556 if (tg->io_disp[rw] + 1 <= io_allowed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400557 if (wait)
558 *wait = 0;
559 return 1;
560 }
561
Vivek Goyal8e89d132010-09-15 17:06:37 -0400562 /* Calc approx time to dispatch */
563 jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
564
565 if (jiffy_wait > jiffy_elapsed)
566 jiffy_wait = jiffy_wait - jiffy_elapsed;
567 else
568 jiffy_wait = 1;
569
570 if (wait)
571 *wait = jiffy_wait;
572 return 0;
573}
574
575static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
576 struct bio *bio, unsigned long *wait)
577{
578 bool rw = bio_data_dir(bio);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200579 u64 bytes_allowed, extra_bytes, tmp;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400580 unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
Vivek Goyale43473b2010-09-15 17:06:35 -0400581
582 jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
583
584 /* Slice has just started. Consider one slice interval */
585 if (!jiffy_elapsed)
586 jiffy_elapsed_rnd = throtl_slice;
587
588 jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
589
Vivek Goyal5e901a22010-10-01 21:16:38 +0200590 tmp = tg->bps[rw] * jiffy_elapsed_rnd;
591 do_div(tmp, HZ);
Vivek Goyal3aad5d32010-10-01 14:51:14 +0200592 bytes_allowed = tmp;
Vivek Goyale43473b2010-09-15 17:06:35 -0400593
594 if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
595 if (wait)
596 *wait = 0;
597 return 1;
598 }
599
600 /* Calc approx time to dispatch */
601 extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
602 jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
603
604 if (!jiffy_wait)
605 jiffy_wait = 1;
606
607 /*
608 * This wait time is without taking into consideration the rounding
609 * up we did. Add that time also.
610 */
611 jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
Vivek Goyale43473b2010-09-15 17:06:35 -0400612 if (wait)
613 *wait = jiffy_wait;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400614 return 0;
615}
Vivek Goyale43473b2010-09-15 17:06:35 -0400616
Vivek Goyalaf75cd32011-05-19 15:38:31 -0400617static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
618 if (tg->bps[rw] == -1 && tg->iops[rw] == -1)
619 return 1;
620 return 0;
621}
622
Vivek Goyal8e89d132010-09-15 17:06:37 -0400623/*
624 * Returns whether one can dispatch a bio or not. Also returns approx number
625 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
626 */
627static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
628 struct bio *bio, unsigned long *wait)
629{
630 bool rw = bio_data_dir(bio);
631 unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
632
633 /*
634 * Currently whole state machine of group depends on first bio
635 * queued in the group bio list. So one should not be calling
636 * this function with a different bio if there are other bios
637 * queued.
638 */
639 BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
640
641 /* If tg->bps = -1, then BW is unlimited */
642 if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
643 if (wait)
644 *wait = 0;
645 return 1;
646 }
647
648 /*
649 * If previous slice expired, start a new one otherwise renew/extend
650 * existing slice to make sure it is at least throtl_slice interval
651 * long since now.
652 */
653 if (throtl_slice_used(td, tg, rw))
654 throtl_start_new_slice(td, tg, rw);
655 else {
656 if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
657 throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
658 }
659
660 if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
661 && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
662 if (wait)
663 *wait = 0;
664 return 1;
665 }
666
667 max_wait = max(bps_wait, iops_wait);
668
669 if (wait)
670 *wait = max_wait;
671
672 if (time_before(tg->slice_end[rw], jiffies + max_wait))
673 throtl_extend_slice(td, tg, rw, jiffies + max_wait);
Vivek Goyale43473b2010-09-15 17:06:35 -0400674
675 return 0;
676}
677
Tejun Heo3c798392012-04-16 13:57:25 -0700678static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes,
Tejun Heo629ed0b2012-04-01 14:38:44 -0700679 int rw)
680{
Tejun Heo8a3d2612012-04-01 14:38:44 -0700681 struct throtl_grp *tg = blkg_to_tg(blkg);
682 struct tg_stats_cpu *stats_cpu;
Tejun Heo629ed0b2012-04-01 14:38:44 -0700683 unsigned long flags;
684
685 /* If per cpu stats are not allocated yet, don't do any accounting. */
Tejun Heo8a3d2612012-04-01 14:38:44 -0700686 if (tg->stats_cpu == NULL)
Tejun Heo629ed0b2012-04-01 14:38:44 -0700687 return;
688
689 /*
690 * Disabling interrupts to provide mutual exclusion between two
691 * writes on same cpu. It probably is not needed for 64bit. Not
692 * optimizing that case yet.
693 */
694 local_irq_save(flags);
695
Tejun Heo8a3d2612012-04-01 14:38:44 -0700696 stats_cpu = this_cpu_ptr(tg->stats_cpu);
Tejun Heo629ed0b2012-04-01 14:38:44 -0700697
Tejun Heo629ed0b2012-04-01 14:38:44 -0700698 blkg_rwstat_add(&stats_cpu->serviced, rw, 1);
699 blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes);
700
701 local_irq_restore(flags);
702}
703
Vivek Goyale43473b2010-09-15 17:06:35 -0400704static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
705{
706 bool rw = bio_data_dir(bio);
Vivek Goyale43473b2010-09-15 17:06:35 -0400707
708 /* Charge the bio to the group */
709 tg->bytes_disp[rw] += bio->bi_size;
Vivek Goyal8e89d132010-09-15 17:06:37 -0400710 tg->io_disp[rw]++;
Vivek Goyale43473b2010-09-15 17:06:35 -0400711
Tejun Heo629ed0b2012-04-01 14:38:44 -0700712 throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw);
Vivek Goyale43473b2010-09-15 17:06:35 -0400713}
714
715static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
716 struct bio *bio)
717{
718 bool rw = bio_data_dir(bio);
719
720 bio_list_add(&tg->bio_lists[rw], bio);
721 /* Take a bio reference on tg */
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800722 blkg_get(tg_to_blkg(tg));
Vivek Goyale43473b2010-09-15 17:06:35 -0400723 tg->nr_queued[rw]++;
724 td->nr_queued[rw]++;
725 throtl_enqueue_tg(td, tg);
726}
727
728static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
729{
730 unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
731 struct bio *bio;
732
733 if ((bio = bio_list_peek(&tg->bio_lists[READ])))
734 tg_may_dispatch(td, tg, bio, &read_wait);
735
736 if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
737 tg_may_dispatch(td, tg, bio, &write_wait);
738
739 min_wait = min(read_wait, write_wait);
740 disptime = jiffies + min_wait;
741
Vivek Goyale43473b2010-09-15 17:06:35 -0400742 /* Update dispatch time */
743 throtl_dequeue_tg(td, tg);
744 tg->disptime = disptime;
745 throtl_enqueue_tg(td, tg);
746}
747
748static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
749 bool rw, struct bio_list *bl)
750{
751 struct bio *bio;
752
753 bio = bio_list_pop(&tg->bio_lists[rw]);
754 tg->nr_queued[rw]--;
Tejun Heo1adaf3d2012-03-05 13:15:15 -0800755 /* Drop bio reference on blkg */
756 blkg_put(tg_to_blkg(tg));
Vivek Goyale43473b2010-09-15 17:06:35 -0400757
758 BUG_ON(td->nr_queued[rw] <= 0);
759 td->nr_queued[rw]--;
760
761 throtl_charge_bio(tg, bio);
762 bio_list_add(bl, bio);
763 bio->bi_rw |= REQ_THROTTLED;
764
765 throtl_trim_slice(td, tg, rw);
766}
767
768static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
769 struct bio_list *bl)
770{
771 unsigned int nr_reads = 0, nr_writes = 0;
772 unsigned int max_nr_reads = throtl_grp_quantum*3/4;
Vivek Goyalc2f68052010-11-15 19:32:42 +0100773 unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
Vivek Goyale43473b2010-09-15 17:06:35 -0400774 struct bio *bio;
775
776 /* Try to dispatch 75% READS and 25% WRITES */
777
778 while ((bio = bio_list_peek(&tg->bio_lists[READ]))
779 && tg_may_dispatch(td, tg, bio, NULL)) {
780
781 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
782 nr_reads++;
783
784 if (nr_reads >= max_nr_reads)
785 break;
786 }
787
788 while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
789 && tg_may_dispatch(td, tg, bio, NULL)) {
790
791 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
792 nr_writes++;
793
794 if (nr_writes >= max_nr_writes)
795 break;
796 }
797
798 return nr_reads + nr_writes;
799}
800
801static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl)
802{
803 unsigned int nr_disp = 0;
804 struct throtl_grp *tg;
805 struct throtl_rb_root *st = &td->tg_service_tree;
806
807 while (1) {
808 tg = throtl_rb_first(st);
809
810 if (!tg)
811 break;
812
813 if (time_before(jiffies, tg->disptime))
814 break;
815
816 throtl_dequeue_tg(td, tg);
817
818 nr_disp += throtl_dispatch_tg(td, tg, bl);
819
820 if (tg->nr_queued[0] || tg->nr_queued[1]) {
821 tg_update_disptime(td, tg);
822 throtl_enqueue_tg(td, tg);
823 }
824
825 if (nr_disp >= throtl_quantum)
826 break;
827 }
828
829 return nr_disp;
830}
831
Vivek Goyalfe071432010-10-01 14:49:49 +0200832static void throtl_process_limit_change(struct throtl_data *td)
833{
Tejun Heo4eef3042012-03-05 13:15:18 -0800834 struct request_queue *q = td->queue;
Tejun Heo3c798392012-04-16 13:57:25 -0700835 struct blkcg_gq *blkg, *n;
Vivek Goyalfe071432010-10-01 14:49:49 +0200836
Vivek Goyalde701c72011-03-07 21:09:32 +0100837 if (!td->limits_changed)
Vivek Goyalfe071432010-10-01 14:49:49 +0200838 return;
839
Vivek Goyalde701c72011-03-07 21:09:32 +0100840 xchg(&td->limits_changed, false);
Vivek Goyalfe071432010-10-01 14:49:49 +0200841
Vivek Goyalde701c72011-03-07 21:09:32 +0100842 throtl_log(td, "limits changed");
Vivek Goyalfe071432010-10-01 14:49:49 +0200843
Tejun Heoe8989fa2012-03-05 13:15:20 -0800844 list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
Tejun Heo4eef3042012-03-05 13:15:18 -0800845 struct throtl_grp *tg = blkg_to_tg(blkg);
846
Vivek Goyalde701c72011-03-07 21:09:32 +0100847 if (!tg->limits_changed)
848 continue;
Vivek Goyalfe071432010-10-01 14:49:49 +0200849
Vivek Goyalde701c72011-03-07 21:09:32 +0100850 if (!xchg(&tg->limits_changed, false))
851 continue;
852
853 throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
854 " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
855 tg->iops[READ], tg->iops[WRITE]);
856
Vivek Goyal04521db2011-03-22 21:54:29 +0100857 /*
858 * Restart the slices for both READ and WRITES. It
859 * might happen that a group's limit are dropped
860 * suddenly and we don't want to account recently
861 * dispatched IO with new low rate
862 */
863 throtl_start_new_slice(td, tg, 0);
864 throtl_start_new_slice(td, tg, 1);
865
Vivek Goyalde701c72011-03-07 21:09:32 +0100866 if (throtl_tg_on_rr(tg))
867 tg_update_disptime(td, tg);
868 }
Vivek Goyalfe071432010-10-01 14:49:49 +0200869}
870
Vivek Goyale43473b2010-09-15 17:06:35 -0400871/* Dispatch throttled bios. Should be called without queue lock held. */
872static int throtl_dispatch(struct request_queue *q)
873{
874 struct throtl_data *td = q->td;
875 unsigned int nr_disp = 0;
876 struct bio_list bio_list_on_stack;
877 struct bio *bio;
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100878 struct blk_plug plug;
Vivek Goyale43473b2010-09-15 17:06:35 -0400879
880 spin_lock_irq(q->queue_lock);
881
Vivek Goyalfe071432010-10-01 14:49:49 +0200882 throtl_process_limit_change(td);
883
Vivek Goyale43473b2010-09-15 17:06:35 -0400884 if (!total_nr_queued(td))
885 goto out;
886
887 bio_list_init(&bio_list_on_stack);
888
Joe Perchesd2f31a52011-06-13 20:19:27 +0200889 throtl_log(td, "dispatch nr_queued=%u read=%u write=%u",
Vivek Goyale43473b2010-09-15 17:06:35 -0400890 total_nr_queued(td), td->nr_queued[READ],
891 td->nr_queued[WRITE]);
892
893 nr_disp = throtl_select_dispatch(td, &bio_list_on_stack);
894
895 if (nr_disp)
896 throtl_log(td, "bios disp=%u", nr_disp);
897
898 throtl_schedule_next_dispatch(td);
899out:
900 spin_unlock_irq(q->queue_lock);
901
902 /*
903 * If we dispatched some requests, unplug the queue to make sure
904 * immediate dispatch
905 */
906 if (nr_disp) {
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100907 blk_start_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400908 while((bio = bio_list_pop(&bio_list_on_stack)))
909 generic_make_request(bio);
Vivek Goyal69d60eb2011-03-09 08:27:37 +0100910 blk_finish_plug(&plug);
Vivek Goyale43473b2010-09-15 17:06:35 -0400911 }
912 return nr_disp;
913}
914
915void blk_throtl_work(struct work_struct *work)
916{
917 struct throtl_data *td = container_of(work, struct throtl_data,
918 throtl_work.work);
919 struct request_queue *q = td->queue;
920
921 throtl_dispatch(q);
922}
923
924/* Call with queue lock held */
Vivek Goyal450adcb2011-03-01 13:40:54 -0500925static void
926throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay)
Vivek Goyale43473b2010-09-15 17:06:35 -0400927{
928
Vivek Goyale43473b2010-09-15 17:06:35 -0400929 struct delayed_work *dwork = &td->throtl_work;
930
Vivek Goyal04521db2011-03-22 21:54:29 +0100931 /* schedule work if limits changed even if no bio is queued */
Joe Perchesd2f31a52011-06-13 20:19:27 +0200932 if (total_nr_queued(td) || td->limits_changed) {
Vivek Goyale43473b2010-09-15 17:06:35 -0400933 /*
934 * We might have a work scheduled to be executed in future.
935 * Cancel that and schedule a new one.
936 */
937 __cancel_delayed_work(dwork);
Vivek Goyal450adcb2011-03-01 13:40:54 -0500938 queue_delayed_work(kthrotld_workqueue, dwork, delay);
Vivek Goyale43473b2010-09-15 17:06:35 -0400939 throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
940 delay, jiffies);
941 }
942}
Vivek Goyale43473b2010-09-15 17:06:35 -0400943
Tejun Heof95a04a2012-04-16 13:57:26 -0700944static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
945 struct blkg_policy_data *pd, int off)
Tejun Heo41b38b62012-04-01 14:38:44 -0700946{
Tejun Heof95a04a2012-04-16 13:57:26 -0700947 struct throtl_grp *tg = pd_to_tg(pd);
Tejun Heo41b38b62012-04-01 14:38:44 -0700948 struct blkg_rwstat rwstat = { }, tmp;
949 int i, cpu;
950
951 for_each_possible_cpu(cpu) {
Tejun Heo8a3d2612012-04-01 14:38:44 -0700952 struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu);
Tejun Heo41b38b62012-04-01 14:38:44 -0700953
954 tmp = blkg_rwstat_read((void *)sc + off);
955 for (i = 0; i < BLKG_RWSTAT_NR; i++)
956 rwstat.cnt[i] += tmp.cnt[i];
957 }
958
Tejun Heof95a04a2012-04-16 13:57:26 -0700959 return __blkg_prfill_rwstat(sf, pd, &rwstat);
Tejun Heo41b38b62012-04-01 14:38:44 -0700960}
961
Tejun Heo8a3d2612012-04-01 14:38:44 -0700962static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft,
963 struct seq_file *sf)
Tejun Heo41b38b62012-04-01 14:38:44 -0700964{
Tejun Heo3c798392012-04-16 13:57:25 -0700965 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
Tejun Heo41b38b62012-04-01 14:38:44 -0700966
Tejun Heo3c798392012-04-16 13:57:25 -0700967 blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl,
Tejun Heo5bc4afb12012-04-01 14:38:45 -0700968 cft->private, true);
Tejun Heo41b38b62012-04-01 14:38:44 -0700969 return 0;
970}
971
Tejun Heof95a04a2012-04-16 13:57:26 -0700972static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
973 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700974{
Tejun Heof95a04a2012-04-16 13:57:26 -0700975 struct throtl_grp *tg = pd_to_tg(pd);
976 u64 v = *(u64 *)((void *)tg + off);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700977
Tejun Heoaf133ce2012-04-01 14:38:44 -0700978 if (v == -1)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700979 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -0700980 return __blkg_prfill_u64(sf, pd, v);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700981}
982
Tejun Heof95a04a2012-04-16 13:57:26 -0700983static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
984 int off)
Tejun Heo60c2bc22012-04-01 14:38:43 -0700985{
Tejun Heof95a04a2012-04-16 13:57:26 -0700986 struct throtl_grp *tg = pd_to_tg(pd);
987 unsigned int v = *(unsigned int *)((void *)tg + off);
Tejun Heoaf133ce2012-04-01 14:38:44 -0700988
989 if (v == -1)
990 return 0;
Tejun Heof95a04a2012-04-16 13:57:26 -0700991 return __blkg_prfill_u64(sf, pd, v);
Tejun Heoaf133ce2012-04-01 14:38:44 -0700992}
993
994static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft,
995 struct seq_file *sf)
996{
Tejun Heo3c798392012-04-16 13:57:25 -0700997 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64,
998 &blkcg_policy_throtl, cft->private, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -0700999 return 0;
1000}
1001
Tejun Heoaf133ce2012-04-01 14:38:44 -07001002static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft,
1003 struct seq_file *sf)
Vivek Goyale43473b2010-09-15 17:06:35 -04001004{
Tejun Heo3c798392012-04-16 13:57:25 -07001005 blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint,
1006 &blkcg_policy_throtl, cft->private, false);
Tejun Heoaf133ce2012-04-01 14:38:44 -07001007 return 0;
Vivek Goyale43473b2010-09-15 17:06:35 -04001008}
1009
Tejun Heoaf133ce2012-04-01 14:38:44 -07001010static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf,
1011 bool is_u64)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001012{
Tejun Heo3c798392012-04-16 13:57:25 -07001013 struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001014 struct blkg_conf_ctx ctx;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001015 struct throtl_grp *tg;
Tejun Heoa2b16932012-04-13 13:11:33 -07001016 struct throtl_data *td;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001017 int ret;
1018
Tejun Heo3c798392012-04-16 13:57:25 -07001019 ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001020 if (ret)
1021 return ret;
1022
Tejun Heoaf133ce2012-04-01 14:38:44 -07001023 tg = blkg_to_tg(ctx.blkg);
Tejun Heoa2b16932012-04-13 13:11:33 -07001024 td = ctx.blkg->q->td;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001025
Tejun Heoa2b16932012-04-13 13:11:33 -07001026 if (!ctx.v)
1027 ctx.v = -1;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001028
Tejun Heoa2b16932012-04-13 13:11:33 -07001029 if (is_u64)
1030 *(u64 *)((void *)tg + cft->private) = ctx.v;
1031 else
1032 *(unsigned int *)((void *)tg + cft->private) = ctx.v;
Tejun Heoaf133ce2012-04-01 14:38:44 -07001033
Tejun Heoa2b16932012-04-13 13:11:33 -07001034 /* XXX: we don't need the following deferred processing */
1035 xchg(&tg->limits_changed, true);
1036 xchg(&td->limits_changed, true);
1037 throtl_schedule_delayed_work(td, 0);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001038
1039 blkg_conf_finish(&ctx);
Tejun Heoa2b16932012-04-13 13:11:33 -07001040 return 0;
Tejun Heo60c2bc22012-04-01 14:38:43 -07001041}
1042
Tejun Heoaf133ce2012-04-01 14:38:44 -07001043static int tg_set_conf_u64(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, true);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001047}
1048
Tejun Heoaf133ce2012-04-01 14:38:44 -07001049static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft,
1050 const char *buf)
Tejun Heo60c2bc22012-04-01 14:38:43 -07001051{
Tejun Heoaf133ce2012-04-01 14:38:44 -07001052 return tg_set_conf(cgrp, cft, buf, false);
Tejun Heo60c2bc22012-04-01 14:38:43 -07001053}
1054
1055static struct cftype throtl_files[] = {
1056 {
1057 .name = "throttle.read_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001058 .private = offsetof(struct throtl_grp, bps[READ]),
1059 .read_seq_string = tg_print_conf_u64,
1060 .write_string = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001061 .max_write_len = 256,
1062 },
1063 {
1064 .name = "throttle.write_bps_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001065 .private = offsetof(struct throtl_grp, bps[WRITE]),
1066 .read_seq_string = tg_print_conf_u64,
1067 .write_string = tg_set_conf_u64,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001068 .max_write_len = 256,
1069 },
1070 {
1071 .name = "throttle.read_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001072 .private = offsetof(struct throtl_grp, iops[READ]),
1073 .read_seq_string = tg_print_conf_uint,
1074 .write_string = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001075 .max_write_len = 256,
1076 },
1077 {
1078 .name = "throttle.write_iops_device",
Tejun Heoaf133ce2012-04-01 14:38:44 -07001079 .private = offsetof(struct throtl_grp, iops[WRITE]),
1080 .read_seq_string = tg_print_conf_uint,
1081 .write_string = tg_set_conf_uint,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001082 .max_write_len = 256,
1083 },
1084 {
1085 .name = "throttle.io_service_bytes",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001086 .private = offsetof(struct tg_stats_cpu, service_bytes),
Tejun Heo8a3d2612012-04-01 14:38:44 -07001087 .read_seq_string = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001088 },
1089 {
1090 .name = "throttle.io_serviced",
Tejun Heo5bc4afb12012-04-01 14:38:45 -07001091 .private = offsetof(struct tg_stats_cpu, serviced),
Tejun Heo8a3d2612012-04-01 14:38:44 -07001092 .read_seq_string = tg_print_cpu_rwstat,
Tejun Heo60c2bc22012-04-01 14:38:43 -07001093 },
1094 { } /* terminate */
1095};
1096
Vivek Goyalda527772011-03-02 19:05:33 -05001097static void throtl_shutdown_wq(struct request_queue *q)
Vivek Goyale43473b2010-09-15 17:06:35 -04001098{
1099 struct throtl_data *td = q->td;
1100
1101 cancel_delayed_work_sync(&td->throtl_work);
1102}
1103
Tejun Heo3c798392012-04-16 13:57:25 -07001104static struct blkcg_policy blkcg_policy_throtl = {
Tejun Heof9fcc2d2012-04-16 13:57:27 -07001105 .pd_size = sizeof(struct throtl_grp),
1106 .cftypes = throtl_files,
1107
1108 .pd_init_fn = throtl_pd_init,
1109 .pd_exit_fn = throtl_pd_exit,
1110 .pd_reset_stats_fn = throtl_pd_reset_stats,
Vivek Goyale43473b2010-09-15 17:06:35 -04001111};
1112
Tejun Heobc16a4f2011-10-19 14:33:01 +02001113bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
Vivek Goyale43473b2010-09-15 17:06:35 -04001114{
1115 struct throtl_data *td = q->td;
1116 struct throtl_grp *tg;
Vivek Goyale43473b2010-09-15 17:06:35 -04001117 bool rw = bio_data_dir(bio), update_disptime = true;
Tejun Heo3c798392012-04-16 13:57:25 -07001118 struct blkcg *blkcg;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001119 bool throttled = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001120
1121 if (bio->bi_rw & REQ_THROTTLED) {
1122 bio->bi_rw &= ~REQ_THROTTLED;
Tejun Heobc16a4f2011-10-19 14:33:01 +02001123 goto out;
Vivek Goyale43473b2010-09-15 17:06:35 -04001124 }
1125
Tejun Heo671058f2012-03-05 13:15:29 -08001126 /* bio_associate_current() needs ioc, try creating */
1127 create_io_context(GFP_ATOMIC, q->node);
1128
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001129 /*
1130 * A throtl_grp pointer retrieved under rcu can be used to access
1131 * basic fields like stats and io rates. If a group has no rules,
1132 * just update the dispatch stats in lockless manner and return.
1133 */
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001134 rcu_read_lock();
Tejun Heo3c798392012-04-16 13:57:25 -07001135 blkcg = bio_blkcg(bio);
Tejun Heocd1604f2012-03-05 13:15:06 -08001136 tg = throtl_lookup_tg(td, blkcg);
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001137 if (tg) {
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001138 if (tg_no_rule_group(tg, rw)) {
Tejun Heo629ed0b2012-04-01 14:38:44 -07001139 throtl_update_dispatch_stats(tg_to_blkg(tg),
1140 bio->bi_size, bio->bi_rw);
Tejun Heo2a7f1242012-03-05 13:15:01 -08001141 goto out_unlock_rcu;
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001142 }
1143 }
Vivek Goyalaf75cd32011-05-19 15:38:31 -04001144
1145 /*
1146 * Either group has not been allocated yet or it is not an unlimited
1147 * IO group
1148 */
Vivek Goyale43473b2010-09-15 17:06:35 -04001149 spin_lock_irq(q->queue_lock);
Tejun Heocd1604f2012-03-05 13:15:06 -08001150 tg = throtl_lookup_create_tg(td, blkcg);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001151 if (unlikely(!tg))
1152 goto out_unlock;
Vivek Goyalf469a7b2011-05-19 15:38:23 -04001153
Vivek Goyale43473b2010-09-15 17:06:35 -04001154 if (tg->nr_queued[rw]) {
1155 /*
1156 * There is already another bio queued in same dir. No
1157 * need to update dispatch time.
1158 */
Vivek Goyal231d7042011-03-07 21:05:14 +01001159 update_disptime = false;
Vivek Goyale43473b2010-09-15 17:06:35 -04001160 goto queue_bio;
Vivek Goyalde701c72011-03-07 21:09:32 +01001161
Vivek Goyale43473b2010-09-15 17:06:35 -04001162 }
1163
1164 /* Bio is with-in rate limit of group */
1165 if (tg_may_dispatch(td, tg, bio, NULL)) {
1166 throtl_charge_bio(tg, bio);
Vivek Goyal04521db2011-03-22 21:54:29 +01001167
1168 /*
1169 * We need to trim slice even when bios are not being queued
1170 * otherwise it might happen that a bio is not queued for
1171 * a long time and slice keeps on extending and trim is not
1172 * called for a long time. Now if limits are reduced suddenly
1173 * we take into account all the IO dispatched so far at new
1174 * low rate and * newly queued IO gets a really long dispatch
1175 * time.
1176 *
1177 * So keep on trimming slice even if bio is not queued.
1178 */
1179 throtl_trim_slice(td, tg, rw);
Tejun Heobc16a4f2011-10-19 14:33:01 +02001180 goto out_unlock;
Vivek Goyale43473b2010-09-15 17:06:35 -04001181 }
1182
1183queue_bio:
Joe Perchesfd16d262011-06-13 10:42:49 +02001184 throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
Vivek Goyal8e89d132010-09-15 17:06:37 -04001185 " iodisp=%u iops=%u queued=%d/%d",
1186 rw == READ ? 'R' : 'W',
Vivek Goyale43473b2010-09-15 17:06:35 -04001187 tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
Vivek Goyal8e89d132010-09-15 17:06:37 -04001188 tg->io_disp[rw], tg->iops[rw],
Vivek Goyale43473b2010-09-15 17:06:35 -04001189 tg->nr_queued[READ], tg->nr_queued[WRITE]);
1190
Tejun Heo671058f2012-03-05 13:15:29 -08001191 bio_associate_current(bio);
Vivek Goyale43473b2010-09-15 17:06:35 -04001192 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 Heo2a7f1242012-03-05 13:15:01 -08001202out_unlock_rcu:
1203 rcu_read_unlock();
Tejun Heobc16a4f2011-10-19 14:33:01 +02001204out:
1205 return throttled;
Vivek Goyale43473b2010-09-15 17:06:35 -04001206}
1207
Tejun Heoc9a929d2011-10-19 14:42:16 +02001208/**
1209 * blk_throtl_drain - drain throttled bios
1210 * @q: request_queue to drain throttled bios for
1211 *
1212 * Dispatch all currently throttled bios on @q through ->make_request_fn().
1213 */
1214void blk_throtl_drain(struct request_queue *q)
1215 __releases(q->queue_lock) __acquires(q->queue_lock)
1216{
1217 struct throtl_data *td = q->td;
1218 struct throtl_rb_root *st = &td->tg_service_tree;
1219 struct throtl_grp *tg;
1220 struct bio_list bl;
1221 struct bio *bio;
1222
Andi Kleen8bcb6c72012-03-30 12:33:28 +02001223 queue_lockdep_assert_held(q);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001224
1225 bio_list_init(&bl);
1226
1227 while ((tg = throtl_rb_first(st))) {
1228 throtl_dequeue_tg(td, tg);
1229
1230 while ((bio = bio_list_peek(&tg->bio_lists[READ])))
1231 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1232 while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
1233 tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
1234 }
1235 spin_unlock_irq(q->queue_lock);
1236
1237 while ((bio = bio_list_pop(&bl)))
1238 generic_make_request(bio);
1239
1240 spin_lock_irq(q->queue_lock);
1241}
1242
Vivek Goyale43473b2010-09-15 17:06:35 -04001243int blk_throtl_init(struct request_queue *q)
1244{
1245 struct throtl_data *td;
Tejun Heoa2b16932012-04-13 13:11:33 -07001246 int ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001247
1248 td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
1249 if (!td)
1250 return -ENOMEM;
1251
Vivek Goyale43473b2010-09-15 17:06:35 -04001252 td->tg_service_tree = THROTL_RB_ROOT;
Vivek Goyalde701c72011-03-07 21:09:32 +01001253 td->limits_changed = false;
Vivek Goyala29a1712011-05-19 15:38:19 -04001254 INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
Vivek Goyale43473b2010-09-15 17:06:35 -04001255
Tejun Heocd1604f2012-03-05 13:15:06 -08001256 q->td = td;
Vivek Goyal29b12582011-05-19 15:38:24 -04001257 td->queue = q;
Vivek Goyal02977e42010-10-01 14:49:48 +02001258
Tejun Heoa2b16932012-04-13 13:11:33 -07001259 /* activate policy */
Tejun Heo3c798392012-04-16 13:57:25 -07001260 ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
Tejun Heoa2b16932012-04-13 13:11:33 -07001261 if (ret)
Vivek Goyal29b12582011-05-19 15:38:24 -04001262 kfree(td);
Tejun Heoa2b16932012-04-13 13:11:33 -07001263 return ret;
Vivek Goyale43473b2010-09-15 17:06:35 -04001264}
1265
1266void blk_throtl_exit(struct request_queue *q)
1267{
Tejun Heoc875f4d2012-03-05 13:15:22 -08001268 BUG_ON(!q->td);
Vivek Goyalda527772011-03-02 19:05:33 -05001269 throtl_shutdown_wq(q);
Tejun Heo3c798392012-04-16 13:57:25 -07001270 blkcg_deactivate_policy(q, &blkcg_policy_throtl);
Tejun Heoc9a929d2011-10-19 14:42:16 +02001271 kfree(q->td);
Vivek Goyale43473b2010-09-15 17:06:35 -04001272}
1273
1274static int __init throtl_init(void)
1275{
Vivek Goyal450adcb2011-03-01 13:40:54 -05001276 kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
1277 if (!kthrotld_workqueue)
1278 panic("Failed to create kthrotld\n");
1279
Tejun Heo3c798392012-04-16 13:57:25 -07001280 return blkcg_policy_register(&blkcg_policy_throtl);
Vivek Goyale43473b2010-09-15 17:06:35 -04001281}
1282
1283module_init(throtl_init);