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1 | /* |
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" |
13 | #include "blk.h" |
14 | |
15 | /* Max dispatch from a group in 1 round */ |
16 | static int throtl_grp_quantum = 8; |
17 | |
18 | /* Total max dispatch from all groups in one round */ |
19 | static int throtl_quantum = 32; |
20 | |
21 | /* Throttling is performed over 100ms slice and after that slice is renewed */ |
22 | static unsigned long throtl_slice = HZ/10; /* 100 ms */ |
23 | |
24 | static struct blkcg_policy blkcg_policy_throtl; |
25 | |
26 | /* A workqueue to queue throttle related work */ |
27 | static struct workqueue_struct *kthrotld_workqueue; |
28 | static void throtl_schedule_delayed_work(struct throtl_data *td, |
29 | unsigned long delay); |
30 | |
31 | struct 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 | |
43 | /* Per-cpu group stats */ |
44 | struct 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 | |
51 | struct throtl_grp { |
52 | /* must be the first member */ |
53 | struct blkg_policy_data pd; |
54 | |
55 | /* 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 | |
65 | 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 | |
76 | /* IOPS limits */ |
77 | unsigned int iops[2]; |
78 | |
79 | /* Number of bytes disptached in current slice */ |
80 | uint64_t bytes_disp[2]; |
81 | /* Number of bio's dispatched in current slice */ |
82 | unsigned int io_disp[2]; |
83 | |
84 | /* When did we start a new slice */ |
85 | unsigned long slice_start[2]; |
86 | unsigned long slice_end[2]; |
87 | |
88 | /* Some throttle limits got updated for the group */ |
89 | int limits_changed; |
90 | |
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; |
96 | }; |
97 | |
98 | struct throtl_data |
99 | { |
100 | /* service tree for active throtl groups */ |
101 | struct throtl_rb_root tg_service_tree; |
102 | |
103 | struct request_queue *queue; |
104 | |
105 | /* Total Number of queued bios on READ and WRITE lists */ |
106 | unsigned int nr_queued[2]; |
107 | |
108 | /* |
109 | * number of total undestroyed groups |
110 | */ |
111 | unsigned int nr_undestroyed_grps; |
112 | |
113 | /* Work for dispatching throttled bios */ |
114 | struct delayed_work throtl_work; |
115 | |
116 | int limits_changed; |
117 | }; |
118 | |
119 | /* list and work item to allocate percpu group stats */ |
120 | static DEFINE_SPINLOCK(tg_stats_alloc_lock); |
121 | static LIST_HEAD(tg_stats_alloc_list); |
122 | |
123 | static void tg_stats_alloc_fn(struct work_struct *); |
124 | static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn); |
125 | |
126 | static 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 | |
131 | static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) |
132 | { |
133 | return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); |
134 | } |
135 | |
136 | static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) |
137 | { |
138 | return pd_to_blkg(&tg->pd); |
139 | } |
140 | |
141 | static inline struct throtl_grp *td_root_tg(struct throtl_data *td) |
142 | { |
143 | return blkg_to_tg(td->queue->root_blkg); |
144 | } |
145 | |
146 | enum tg_state_flags { |
147 | THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */ |
148 | }; |
149 | |
150 | #define THROTL_TG_FNS(name) \ |
151 | static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \ |
152 | { \ |
153 | (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \ |
154 | } \ |
155 | static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \ |
156 | { \ |
157 | (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \ |
158 | } \ |
159 | static inline int throtl_tg_##name(const struct throtl_grp *tg) \ |
160 | { \ |
161 | return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \ |
162 | } |
163 | |
164 | THROTL_TG_FNS(on_rr); |
165 | |
166 | #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) |
172 | |
173 | #define throtl_log(td, fmt, args...) \ |
174 | blk_add_trace_msg((td)->queue, "throtl " fmt, ##args) |
175 | |
176 | static inline unsigned int total_nr_queued(struct throtl_data *td) |
177 | { |
178 | return td->nr_queued[0] + td->nr_queued[1]; |
179 | } |
180 | |
181 | /* |
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 | */ |
186 | static 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 | |
192 | alloc_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 | |
219 | static void throtl_pd_init(struct blkcg_gq *blkg) |
220 | { |
221 | struct throtl_grp *tg = blkg_to_tg(blkg); |
222 | unsigned long flags; |
223 | |
224 | 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 | |
229 | tg->bps[READ] = -1; |
230 | tg->bps[WRITE] = -1; |
231 | tg->iops[READ] = -1; |
232 | tg->iops[WRITE] = -1; |
233 | |
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 | */ |
239 | spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
240 | list_add(&tg->stats_alloc_node, &tg_stats_alloc_list); |
241 | queue_delayed_work(system_nrt_wq, &tg_stats_alloc_work, 0); |
242 | spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
243 | } |
244 | |
245 | static void throtl_pd_exit(struct blkcg_gq *blkg) |
246 | { |
247 | struct throtl_grp *tg = blkg_to_tg(blkg); |
248 | unsigned long flags; |
249 | |
250 | spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
251 | list_del_init(&tg->stats_alloc_node); |
252 | spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
253 | |
254 | free_percpu(tg->stats_cpu); |
255 | } |
256 | |
257 | static void throtl_pd_reset_stats(struct blkcg_gq *blkg) |
258 | { |
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 | } |
271 | } |
272 | |
273 | static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td, |
274 | struct blkcg *blkcg) |
275 | { |
276 | /* |
277 | * This is the common case when there are no blkcgs. Avoid lookup |
278 | * in this case |
279 | */ |
280 | if (blkcg == &blkcg_root) |
281 | return td_root_tg(td); |
282 | |
283 | return blkg_to_tg(blkg_lookup(blkcg, td->queue)); |
284 | } |
285 | |
286 | static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, |
287 | struct blkcg *blkcg) |
288 | { |
289 | struct request_queue *q = td->queue; |
290 | struct throtl_grp *tg = NULL; |
291 | |
292 | /* |
293 | * This is the common case when there are no blkcgs. Avoid lookup |
294 | * in this case |
295 | */ |
296 | if (blkcg == &blkcg_root) { |
297 | tg = td_root_tg(td); |
298 | } else { |
299 | struct blkcg_gq *blkg; |
300 | |
301 | blkg = blkg_lookup_create(blkcg, q); |
302 | |
303 | /* if %NULL and @q is alive, fall back to root_tg */ |
304 | if (!IS_ERR(blkg)) |
305 | tg = blkg_to_tg(blkg); |
306 | else if (!blk_queue_dead(q)) |
307 | tg = td_root_tg(td); |
308 | } |
309 | |
310 | return tg; |
311 | } |
312 | |
313 | static 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 | |
328 | static 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 | |
334 | static 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 | |
342 | static 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 | |
353 | static void |
354 | tg_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 | |
381 | static 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 | |
390 | static 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 | |
396 | static 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 | |
402 | static 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 | |
408 | static 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)) |
423 | throtl_schedule_delayed_work(td, 0); |
424 | else |
425 | throtl_schedule_delayed_work(td, (st->min_disptime - jiffies)); |
426 | } |
427 | |
428 | static inline void |
429 | throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) |
430 | { |
431 | tg->bytes_disp[rw] = 0; |
432 | tg->io_disp[rw] = 0; |
433 | 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 | |
440 | static 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 | |
446 | static 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 */ |
456 | static bool |
457 | throtl_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 */ |
466 | static inline void |
467 | throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) |
468 | { |
469 | unsigned long nr_slices, time_elapsed, io_trim; |
470 | u64 bytes_trim, tmp; |
471 | |
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 | |
482 | /* |
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 | |
492 | time_elapsed = jiffies - tg->slice_start[rw]; |
493 | |
494 | nr_slices = time_elapsed / throtl_slice; |
495 | |
496 | if (!nr_slices) |
497 | return; |
498 | tmp = tg->bps[rw] * throtl_slice * nr_slices; |
499 | do_div(tmp, HZ); |
500 | bytes_trim = tmp; |
501 | |
502 | io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; |
503 | |
504 | if (!bytes_trim && !io_trim) |
505 | 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 | |
512 | if (tg->io_disp[rw] >= io_trim) |
513 | tg->io_disp[rw] -= io_trim; |
514 | else |
515 | tg->io_disp[rw] = 0; |
516 | |
517 | tg->slice_start[rw] += nr_slices * throtl_slice; |
518 | |
519 | throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu" |
520 | " start=%lu end=%lu jiffies=%lu", |
521 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
522 | tg->slice_start[rw], tg->slice_end[rw], jiffies); |
523 | } |
524 | |
525 | static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg, |
526 | struct bio *bio, unsigned long *wait) |
527 | { |
528 | bool rw = bio_data_dir(bio); |
529 | unsigned int io_allowed; |
530 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
531 | u64 tmp; |
532 | |
533 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
534 | |
535 | /* 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 | |
541 | /* |
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; |
555 | |
556 | if (tg->io_disp[rw] + 1 <= io_allowed) { |
557 | if (wait) |
558 | *wait = 0; |
559 | return 1; |
560 | } |
561 | |
562 | /* 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 | |
575 | static 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); |
579 | u64 bytes_allowed, extra_bytes, tmp; |
580 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
581 | |
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 | |
590 | tmp = tg->bps[rw] * jiffy_elapsed_rnd; |
591 | do_div(tmp, HZ); |
592 | bytes_allowed = tmp; |
593 | |
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); |
612 | if (wait) |
613 | *wait = jiffy_wait; |
614 | return 0; |
615 | } |
616 | |
617 | static 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 | |
623 | /* |
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 | */ |
627 | static 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); |
674 | |
675 | return 0; |
676 | } |
677 | |
678 | static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes, |
679 | int rw) |
680 | { |
681 | struct throtl_grp *tg = blkg_to_tg(blkg); |
682 | struct tg_stats_cpu *stats_cpu; |
683 | unsigned long flags; |
684 | |
685 | /* If per cpu stats are not allocated yet, don't do any accounting. */ |
686 | if (tg->stats_cpu == NULL) |
687 | 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 | |
696 | stats_cpu = this_cpu_ptr(tg->stats_cpu); |
697 | |
698 | 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 | |
704 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) |
705 | { |
706 | bool rw = bio_data_dir(bio); |
707 | |
708 | /* Charge the bio to the group */ |
709 | tg->bytes_disp[rw] += bio->bi_size; |
710 | tg->io_disp[rw]++; |
711 | |
712 | throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw); |
713 | } |
714 | |
715 | static 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 */ |
722 | blkg_get(tg_to_blkg(tg)); |
723 | tg->nr_queued[rw]++; |
724 | td->nr_queued[rw]++; |
725 | throtl_enqueue_tg(td, tg); |
726 | } |
727 | |
728 | static 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 | |
742 | /* Update dispatch time */ |
743 | throtl_dequeue_tg(td, tg); |
744 | tg->disptime = disptime; |
745 | throtl_enqueue_tg(td, tg); |
746 | } |
747 | |
748 | static 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]--; |
755 | /* Drop bio reference on blkg */ |
756 | blkg_put(tg_to_blkg(tg)); |
757 | |
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 | |
768 | static 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; |
773 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
774 | 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 | |
801 | static 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 | |
832 | static void throtl_process_limit_change(struct throtl_data *td) |
833 | { |
834 | struct request_queue *q = td->queue; |
835 | struct blkcg_gq *blkg, *n; |
836 | |
837 | if (!td->limits_changed) |
838 | return; |
839 | |
840 | xchg(&td->limits_changed, false); |
841 | |
842 | throtl_log(td, "limits changed"); |
843 | |
844 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
845 | struct throtl_grp *tg = blkg_to_tg(blkg); |
846 | |
847 | if (!tg->limits_changed) |
848 | continue; |
849 | |
850 | 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 | |
857 | /* |
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 | |
866 | if (throtl_tg_on_rr(tg)) |
867 | tg_update_disptime(td, tg); |
868 | } |
869 | } |
870 | |
871 | /* Dispatch throttled bios. Should be called without queue lock held. */ |
872 | static 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; |
878 | struct blk_plug plug; |
879 | |
880 | spin_lock_irq(q->queue_lock); |
881 | |
882 | throtl_process_limit_change(td); |
883 | |
884 | if (!total_nr_queued(td)) |
885 | goto out; |
886 | |
887 | bio_list_init(&bio_list_on_stack); |
888 | |
889 | throtl_log(td, "dispatch nr_queued=%u read=%u write=%u", |
890 | 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); |
899 | out: |
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) { |
907 | blk_start_plug(&plug); |
908 | while((bio = bio_list_pop(&bio_list_on_stack))) |
909 | generic_make_request(bio); |
910 | blk_finish_plug(&plug); |
911 | } |
912 | return nr_disp; |
913 | } |
914 | |
915 | void 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 */ |
925 | static void |
926 | throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) |
927 | { |
928 | |
929 | struct delayed_work *dwork = &td->throtl_work; |
930 | |
931 | /* schedule work if limits changed even if no bio is queued */ |
932 | if (total_nr_queued(td) || td->limits_changed) { |
933 | /* |
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); |
938 | queue_delayed_work(kthrotld_workqueue, dwork, delay); |
939 | throtl_log(td, "schedule work. delay=%lu jiffies=%lu", |
940 | delay, jiffies); |
941 | } |
942 | } |
943 | |
944 | static u64 tg_prfill_cpu_rwstat(struct seq_file *sf, |
945 | struct blkg_policy_data *pd, int off) |
946 | { |
947 | struct throtl_grp *tg = pd_to_tg(pd); |
948 | struct blkg_rwstat rwstat = { }, tmp; |
949 | int i, cpu; |
950 | |
951 | for_each_possible_cpu(cpu) { |
952 | struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); |
953 | |
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 | |
959 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
960 | } |
961 | |
962 | static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft, |
963 | struct seq_file *sf) |
964 | { |
965 | struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
966 | |
967 | blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl, |
968 | cft->private, true); |
969 | return 0; |
970 | } |
971 | |
972 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
973 | int off) |
974 | { |
975 | struct throtl_grp *tg = pd_to_tg(pd); |
976 | u64 v = *(u64 *)((void *)tg + off); |
977 | |
978 | if (v == -1) |
979 | return 0; |
980 | return __blkg_prfill_u64(sf, pd, v); |
981 | } |
982 | |
983 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
984 | int off) |
985 | { |
986 | struct throtl_grp *tg = pd_to_tg(pd); |
987 | unsigned int v = *(unsigned int *)((void *)tg + off); |
988 | |
989 | if (v == -1) |
990 | return 0; |
991 | return __blkg_prfill_u64(sf, pd, v); |
992 | } |
993 | |
994 | static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
995 | struct seq_file *sf) |
996 | { |
997 | blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64, |
998 | &blkcg_policy_throtl, cft->private, false); |
999 | return 0; |
1000 | } |
1001 | |
1002 | static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
1003 | struct seq_file *sf) |
1004 | { |
1005 | blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint, |
1006 | &blkcg_policy_throtl, cft->private, false); |
1007 | return 0; |
1008 | } |
1009 | |
1010 | static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, |
1011 | bool is_u64) |
1012 | { |
1013 | struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
1014 | struct blkg_conf_ctx ctx; |
1015 | struct throtl_grp *tg; |
1016 | struct throtl_data *td; |
1017 | int ret; |
1018 | |
1019 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
1020 | if (ret) |
1021 | return ret; |
1022 | |
1023 | tg = blkg_to_tg(ctx.blkg); |
1024 | td = ctx.blkg->q->td; |
1025 | |
1026 | if (!ctx.v) |
1027 | ctx.v = -1; |
1028 | |
1029 | if (is_u64) |
1030 | *(u64 *)((void *)tg + cft->private) = ctx.v; |
1031 | else |
1032 | *(unsigned int *)((void *)tg + cft->private) = ctx.v; |
1033 | |
1034 | /* 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); |
1038 | |
1039 | blkg_conf_finish(&ctx); |
1040 | return 0; |
1041 | } |
1042 | |
1043 | static int tg_set_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
1044 | const char *buf) |
1045 | { |
1046 | return tg_set_conf(cgrp, cft, buf, true); |
1047 | } |
1048 | |
1049 | static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
1050 | const char *buf) |
1051 | { |
1052 | return tg_set_conf(cgrp, cft, buf, false); |
1053 | } |
1054 | |
1055 | static struct cftype throtl_files[] = { |
1056 | { |
1057 | .name = "throttle.read_bps_device", |
1058 | .private = offsetof(struct throtl_grp, bps[READ]), |
1059 | .read_seq_string = tg_print_conf_u64, |
1060 | .write_string = tg_set_conf_u64, |
1061 | .max_write_len = 256, |
1062 | }, |
1063 | { |
1064 | .name = "throttle.write_bps_device", |
1065 | .private = offsetof(struct throtl_grp, bps[WRITE]), |
1066 | .read_seq_string = tg_print_conf_u64, |
1067 | .write_string = tg_set_conf_u64, |
1068 | .max_write_len = 256, |
1069 | }, |
1070 | { |
1071 | .name = "throttle.read_iops_device", |
1072 | .private = offsetof(struct throtl_grp, iops[READ]), |
1073 | .read_seq_string = tg_print_conf_uint, |
1074 | .write_string = tg_set_conf_uint, |
1075 | .max_write_len = 256, |
1076 | }, |
1077 | { |
1078 | .name = "throttle.write_iops_device", |
1079 | .private = offsetof(struct throtl_grp, iops[WRITE]), |
1080 | .read_seq_string = tg_print_conf_uint, |
1081 | .write_string = tg_set_conf_uint, |
1082 | .max_write_len = 256, |
1083 | }, |
1084 | { |
1085 | .name = "throttle.io_service_bytes", |
1086 | .private = offsetof(struct tg_stats_cpu, service_bytes), |
1087 | .read_seq_string = tg_print_cpu_rwstat, |
1088 | }, |
1089 | { |
1090 | .name = "throttle.io_serviced", |
1091 | .private = offsetof(struct tg_stats_cpu, serviced), |
1092 | .read_seq_string = tg_print_cpu_rwstat, |
1093 | }, |
1094 | { } /* terminate */ |
1095 | }; |
1096 | |
1097 | static void throtl_shutdown_wq(struct request_queue *q) |
1098 | { |
1099 | struct throtl_data *td = q->td; |
1100 | |
1101 | cancel_delayed_work_sync(&td->throtl_work); |
1102 | } |
1103 | |
1104 | static struct blkcg_policy blkcg_policy_throtl = { |
1105 | .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, |
1111 | }; |
1112 | |
1113 | bool blk_throtl_bio(struct request_queue *q, struct bio *bio) |
1114 | { |
1115 | struct throtl_data *td = q->td; |
1116 | struct throtl_grp *tg; |
1117 | bool rw = bio_data_dir(bio), update_disptime = true; |
1118 | struct blkcg *blkcg; |
1119 | bool throttled = false; |
1120 | |
1121 | if (bio->bi_rw & REQ_THROTTLED) { |
1122 | bio->bi_rw &= ~REQ_THROTTLED; |
1123 | goto out; |
1124 | } |
1125 | |
1126 | /* |
1127 | * A throtl_grp pointer retrieved under rcu can be used to access |
1128 | * basic fields like stats and io rates. If a group has no rules, |
1129 | * just update the dispatch stats in lockless manner and return. |
1130 | */ |
1131 | rcu_read_lock(); |
1132 | blkcg = bio_blkcg(bio); |
1133 | tg = throtl_lookup_tg(td, blkcg); |
1134 | if (tg) { |
1135 | if (tg_no_rule_group(tg, rw)) { |
1136 | throtl_update_dispatch_stats(tg_to_blkg(tg), |
1137 | bio->bi_size, bio->bi_rw); |
1138 | goto out_unlock_rcu; |
1139 | } |
1140 | } |
1141 | |
1142 | /* |
1143 | * Either group has not been allocated yet or it is not an unlimited |
1144 | * IO group |
1145 | */ |
1146 | spin_lock_irq(q->queue_lock); |
1147 | tg = throtl_lookup_create_tg(td, blkcg); |
1148 | if (unlikely(!tg)) |
1149 | goto out_unlock; |
1150 | |
1151 | if (tg->nr_queued[rw]) { |
1152 | /* |
1153 | * There is already another bio queued in same dir. No |
1154 | * need to update dispatch time. |
1155 | */ |
1156 | update_disptime = false; |
1157 | goto queue_bio; |
1158 | |
1159 | } |
1160 | |
1161 | /* Bio is with-in rate limit of group */ |
1162 | if (tg_may_dispatch(td, tg, bio, NULL)) { |
1163 | throtl_charge_bio(tg, bio); |
1164 | |
1165 | /* |
1166 | * We need to trim slice even when bios are not being queued |
1167 | * otherwise it might happen that a bio is not queued for |
1168 | * a long time and slice keeps on extending and trim is not |
1169 | * called for a long time. Now if limits are reduced suddenly |
1170 | * we take into account all the IO dispatched so far at new |
1171 | * low rate and * newly queued IO gets a really long dispatch |
1172 | * time. |
1173 | * |
1174 | * So keep on trimming slice even if bio is not queued. |
1175 | */ |
1176 | throtl_trim_slice(td, tg, rw); |
1177 | goto out_unlock; |
1178 | } |
1179 | |
1180 | queue_bio: |
1181 | throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu" |
1182 | " iodisp=%u iops=%u queued=%d/%d", |
1183 | rw == READ ? 'R' : 'W', |
1184 | tg->bytes_disp[rw], bio->bi_size, tg->bps[rw], |
1185 | tg->io_disp[rw], tg->iops[rw], |
1186 | tg->nr_queued[READ], tg->nr_queued[WRITE]); |
1187 | |
1188 | bio_associate_current(bio); |
1189 | throtl_add_bio_tg(q->td, tg, bio); |
1190 | throttled = true; |
1191 | |
1192 | if (update_disptime) { |
1193 | tg_update_disptime(td, tg); |
1194 | throtl_schedule_next_dispatch(td); |
1195 | } |
1196 | |
1197 | out_unlock: |
1198 | spin_unlock_irq(q->queue_lock); |
1199 | out_unlock_rcu: |
1200 | rcu_read_unlock(); |
1201 | out: |
1202 | return throttled; |
1203 | } |
1204 | |
1205 | /** |
1206 | * blk_throtl_drain - drain throttled bios |
1207 | * @q: request_queue to drain throttled bios for |
1208 | * |
1209 | * Dispatch all currently throttled bios on @q through ->make_request_fn(). |
1210 | */ |
1211 | void blk_throtl_drain(struct request_queue *q) |
1212 | __releases(q->queue_lock) __acquires(q->queue_lock) |
1213 | { |
1214 | struct throtl_data *td = q->td; |
1215 | struct throtl_rb_root *st = &td->tg_service_tree; |
1216 | struct throtl_grp *tg; |
1217 | struct bio_list bl; |
1218 | struct bio *bio; |
1219 | |
1220 | queue_lockdep_assert_held(q); |
1221 | |
1222 | bio_list_init(&bl); |
1223 | |
1224 | while ((tg = throtl_rb_first(st))) { |
1225 | throtl_dequeue_tg(td, tg); |
1226 | |
1227 | while ((bio = bio_list_peek(&tg->bio_lists[READ]))) |
1228 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
1229 | while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) |
1230 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
1231 | } |
1232 | spin_unlock_irq(q->queue_lock); |
1233 | |
1234 | while ((bio = bio_list_pop(&bl))) |
1235 | generic_make_request(bio); |
1236 | |
1237 | spin_lock_irq(q->queue_lock); |
1238 | } |
1239 | |
1240 | int blk_throtl_init(struct request_queue *q) |
1241 | { |
1242 | struct throtl_data *td; |
1243 | int ret; |
1244 | |
1245 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); |
1246 | if (!td) |
1247 | return -ENOMEM; |
1248 | |
1249 | td->tg_service_tree = THROTL_RB_ROOT; |
1250 | td->limits_changed = false; |
1251 | INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); |
1252 | |
1253 | q->td = td; |
1254 | td->queue = q; |
1255 | |
1256 | /* activate policy */ |
1257 | ret = blkcg_activate_policy(q, &blkcg_policy_throtl); |
1258 | if (ret) |
1259 | kfree(td); |
1260 | return ret; |
1261 | } |
1262 | |
1263 | void blk_throtl_exit(struct request_queue *q) |
1264 | { |
1265 | BUG_ON(!q->td); |
1266 | throtl_shutdown_wq(q); |
1267 | blkcg_deactivate_policy(q, &blkcg_policy_throtl); |
1268 | kfree(q->td); |
1269 | } |
1270 | |
1271 | static int __init throtl_init(void) |
1272 | { |
1273 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
1274 | if (!kthrotld_workqueue) |
1275 | panic("Failed to create kthrotld\n"); |
1276 | |
1277 | return blkcg_policy_register(&blkcg_policy_throtl); |
1278 | } |
1279 | |
1280 | module_init(throtl_init); |
1281 |
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v2.6.34-rc5
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