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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_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 | schedule_delayed_work(dwork, msecs_to_jiffies(10)); |
198 | return; |
199 | } |
200 | } |
201 | |
202 | spin_lock_irq(&tg_stats_alloc_lock); |
203 | |
204 | if (!list_empty(&tg_stats_alloc_list)) { |
205 | struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list, |
206 | struct throtl_grp, |
207 | stats_alloc_node); |
208 | swap(tg->stats_cpu, stats_cpu); |
209 | list_del_init(&tg->stats_alloc_node); |
210 | } |
211 | |
212 | empty = list_empty(&tg_stats_alloc_list); |
213 | spin_unlock_irq(&tg_stats_alloc_lock); |
214 | if (!empty) |
215 | goto alloc_stats; |
216 | } |
217 | |
218 | static void throtl_pd_init(struct blkcg_gq *blkg) |
219 | { |
220 | struct throtl_grp *tg = blkg_to_tg(blkg); |
221 | unsigned long flags; |
222 | |
223 | RB_CLEAR_NODE(&tg->rb_node); |
224 | bio_list_init(&tg->bio_lists[0]); |
225 | bio_list_init(&tg->bio_lists[1]); |
226 | tg->limits_changed = false; |
227 | |
228 | tg->bps[READ] = -1; |
229 | tg->bps[WRITE] = -1; |
230 | tg->iops[READ] = -1; |
231 | tg->iops[WRITE] = -1; |
232 | |
233 | /* |
234 | * Ugh... We need to perform per-cpu allocation for tg->stats_cpu |
235 | * but percpu allocator can't be called from IO path. Queue tg on |
236 | * tg_stats_alloc_list and allocate from work item. |
237 | */ |
238 | spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
239 | list_add(&tg->stats_alloc_node, &tg_stats_alloc_list); |
240 | schedule_delayed_work(&tg_stats_alloc_work, 0); |
241 | spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
242 | } |
243 | |
244 | static void throtl_pd_exit(struct blkcg_gq *blkg) |
245 | { |
246 | struct throtl_grp *tg = blkg_to_tg(blkg); |
247 | unsigned long flags; |
248 | |
249 | spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
250 | list_del_init(&tg->stats_alloc_node); |
251 | spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
252 | |
253 | free_percpu(tg->stats_cpu); |
254 | } |
255 | |
256 | static void throtl_pd_reset_stats(struct blkcg_gq *blkg) |
257 | { |
258 | struct throtl_grp *tg = blkg_to_tg(blkg); |
259 | int cpu; |
260 | |
261 | if (tg->stats_cpu == NULL) |
262 | return; |
263 | |
264 | for_each_possible_cpu(cpu) { |
265 | struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); |
266 | |
267 | blkg_rwstat_reset(&sc->service_bytes); |
268 | blkg_rwstat_reset(&sc->serviced); |
269 | } |
270 | } |
271 | |
272 | static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td, |
273 | struct blkcg *blkcg) |
274 | { |
275 | /* |
276 | * This is the common case when there are no blkcgs. Avoid lookup |
277 | * in this case |
278 | */ |
279 | if (blkcg == &blkcg_root) |
280 | return td_root_tg(td); |
281 | |
282 | return blkg_to_tg(blkg_lookup(blkcg, td->queue)); |
283 | } |
284 | |
285 | static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, |
286 | struct blkcg *blkcg) |
287 | { |
288 | struct request_queue *q = td->queue; |
289 | struct throtl_grp *tg = NULL; |
290 | |
291 | /* |
292 | * This is the common case when there are no blkcgs. Avoid lookup |
293 | * in this case |
294 | */ |
295 | if (blkcg == &blkcg_root) { |
296 | tg = td_root_tg(td); |
297 | } else { |
298 | struct blkcg_gq *blkg; |
299 | |
300 | blkg = blkg_lookup_create(blkcg, q); |
301 | |
302 | /* if %NULL and @q is alive, fall back to root_tg */ |
303 | if (!IS_ERR(blkg)) |
304 | tg = blkg_to_tg(blkg); |
305 | else if (!blk_queue_dying(q)) |
306 | tg = td_root_tg(td); |
307 | } |
308 | |
309 | return tg; |
310 | } |
311 | |
312 | static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root) |
313 | { |
314 | /* Service tree is empty */ |
315 | if (!root->count) |
316 | return NULL; |
317 | |
318 | if (!root->left) |
319 | root->left = rb_first(&root->rb); |
320 | |
321 | if (root->left) |
322 | return rb_entry_tg(root->left); |
323 | |
324 | return NULL; |
325 | } |
326 | |
327 | static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
328 | { |
329 | rb_erase(n, root); |
330 | RB_CLEAR_NODE(n); |
331 | } |
332 | |
333 | static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root) |
334 | { |
335 | if (root->left == n) |
336 | root->left = NULL; |
337 | rb_erase_init(n, &root->rb); |
338 | --root->count; |
339 | } |
340 | |
341 | static void update_min_dispatch_time(struct throtl_rb_root *st) |
342 | { |
343 | struct throtl_grp *tg; |
344 | |
345 | tg = throtl_rb_first(st); |
346 | if (!tg) |
347 | return; |
348 | |
349 | st->min_disptime = tg->disptime; |
350 | } |
351 | |
352 | static void |
353 | tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg) |
354 | { |
355 | struct rb_node **node = &st->rb.rb_node; |
356 | struct rb_node *parent = NULL; |
357 | struct throtl_grp *__tg; |
358 | unsigned long key = tg->disptime; |
359 | int left = 1; |
360 | |
361 | while (*node != NULL) { |
362 | parent = *node; |
363 | __tg = rb_entry_tg(parent); |
364 | |
365 | if (time_before(key, __tg->disptime)) |
366 | node = &parent->rb_left; |
367 | else { |
368 | node = &parent->rb_right; |
369 | left = 0; |
370 | } |
371 | } |
372 | |
373 | if (left) |
374 | st->left = &tg->rb_node; |
375 | |
376 | rb_link_node(&tg->rb_node, parent, node); |
377 | rb_insert_color(&tg->rb_node, &st->rb); |
378 | } |
379 | |
380 | static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) |
381 | { |
382 | struct throtl_rb_root *st = &td->tg_service_tree; |
383 | |
384 | tg_service_tree_add(st, tg); |
385 | throtl_mark_tg_on_rr(tg); |
386 | st->count++; |
387 | } |
388 | |
389 | static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) |
390 | { |
391 | if (!throtl_tg_on_rr(tg)) |
392 | __throtl_enqueue_tg(td, tg); |
393 | } |
394 | |
395 | static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) |
396 | { |
397 | throtl_rb_erase(&tg->rb_node, &td->tg_service_tree); |
398 | throtl_clear_tg_on_rr(tg); |
399 | } |
400 | |
401 | static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) |
402 | { |
403 | if (throtl_tg_on_rr(tg)) |
404 | __throtl_dequeue_tg(td, tg); |
405 | } |
406 | |
407 | static void throtl_schedule_next_dispatch(struct throtl_data *td) |
408 | { |
409 | struct throtl_rb_root *st = &td->tg_service_tree; |
410 | |
411 | /* |
412 | * If there are more bios pending, schedule more work. |
413 | */ |
414 | if (!total_nr_queued(td)) |
415 | return; |
416 | |
417 | BUG_ON(!st->count); |
418 | |
419 | update_min_dispatch_time(st); |
420 | |
421 | if (time_before_eq(st->min_disptime, jiffies)) |
422 | throtl_schedule_delayed_work(td, 0); |
423 | else |
424 | throtl_schedule_delayed_work(td, (st->min_disptime - jiffies)); |
425 | } |
426 | |
427 | static inline void |
428 | throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) |
429 | { |
430 | tg->bytes_disp[rw] = 0; |
431 | tg->io_disp[rw] = 0; |
432 | tg->slice_start[rw] = jiffies; |
433 | tg->slice_end[rw] = jiffies + throtl_slice; |
434 | throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu", |
435 | rw == READ ? 'R' : 'W', tg->slice_start[rw], |
436 | tg->slice_end[rw], jiffies); |
437 | } |
438 | |
439 | static inline void throtl_set_slice_end(struct throtl_data *td, |
440 | struct throtl_grp *tg, bool rw, unsigned long jiffy_end) |
441 | { |
442 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); |
443 | } |
444 | |
445 | static inline void throtl_extend_slice(struct throtl_data *td, |
446 | struct throtl_grp *tg, bool rw, unsigned long jiffy_end) |
447 | { |
448 | tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); |
449 | throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu", |
450 | rw == READ ? 'R' : 'W', tg->slice_start[rw], |
451 | tg->slice_end[rw], jiffies); |
452 | } |
453 | |
454 | /* Determine if previously allocated or extended slice is complete or not */ |
455 | static bool |
456 | throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw) |
457 | { |
458 | if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) |
459 | return 0; |
460 | |
461 | return 1; |
462 | } |
463 | |
464 | /* Trim the used slices and adjust slice start accordingly */ |
465 | static inline void |
466 | throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw) |
467 | { |
468 | unsigned long nr_slices, time_elapsed, io_trim; |
469 | u64 bytes_trim, tmp; |
470 | |
471 | BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); |
472 | |
473 | /* |
474 | * If bps are unlimited (-1), then time slice don't get |
475 | * renewed. Don't try to trim the slice if slice is used. A new |
476 | * slice will start when appropriate. |
477 | */ |
478 | if (throtl_slice_used(td, tg, rw)) |
479 | return; |
480 | |
481 | /* |
482 | * A bio has been dispatched. Also adjust slice_end. It might happen |
483 | * that initially cgroup limit was very low resulting in high |
484 | * slice_end, but later limit was bumped up and bio was dispached |
485 | * sooner, then we need to reduce slice_end. A high bogus slice_end |
486 | * is bad because it does not allow new slice to start. |
487 | */ |
488 | |
489 | throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice); |
490 | |
491 | time_elapsed = jiffies - tg->slice_start[rw]; |
492 | |
493 | nr_slices = time_elapsed / throtl_slice; |
494 | |
495 | if (!nr_slices) |
496 | return; |
497 | tmp = tg->bps[rw] * throtl_slice * nr_slices; |
498 | do_div(tmp, HZ); |
499 | bytes_trim = tmp; |
500 | |
501 | io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; |
502 | |
503 | if (!bytes_trim && !io_trim) |
504 | return; |
505 | |
506 | if (tg->bytes_disp[rw] >= bytes_trim) |
507 | tg->bytes_disp[rw] -= bytes_trim; |
508 | else |
509 | tg->bytes_disp[rw] = 0; |
510 | |
511 | if (tg->io_disp[rw] >= io_trim) |
512 | tg->io_disp[rw] -= io_trim; |
513 | else |
514 | tg->io_disp[rw] = 0; |
515 | |
516 | tg->slice_start[rw] += nr_slices * throtl_slice; |
517 | |
518 | throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu" |
519 | " start=%lu end=%lu jiffies=%lu", |
520 | rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
521 | tg->slice_start[rw], tg->slice_end[rw], jiffies); |
522 | } |
523 | |
524 | static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg, |
525 | struct bio *bio, unsigned long *wait) |
526 | { |
527 | bool rw = bio_data_dir(bio); |
528 | unsigned int io_allowed; |
529 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
530 | u64 tmp; |
531 | |
532 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
533 | |
534 | /* Slice has just started. Consider one slice interval */ |
535 | if (!jiffy_elapsed) |
536 | jiffy_elapsed_rnd = throtl_slice; |
537 | |
538 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); |
539 | |
540 | /* |
541 | * jiffy_elapsed_rnd should not be a big value as minimum iops can be |
542 | * 1 then at max jiffy elapsed should be equivalent of 1 second as we |
543 | * will allow dispatch after 1 second and after that slice should |
544 | * have been trimmed. |
545 | */ |
546 | |
547 | tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd; |
548 | do_div(tmp, HZ); |
549 | |
550 | if (tmp > UINT_MAX) |
551 | io_allowed = UINT_MAX; |
552 | else |
553 | io_allowed = tmp; |
554 | |
555 | if (tg->io_disp[rw] + 1 <= io_allowed) { |
556 | if (wait) |
557 | *wait = 0; |
558 | return 1; |
559 | } |
560 | |
561 | /* Calc approx time to dispatch */ |
562 | jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1; |
563 | |
564 | if (jiffy_wait > jiffy_elapsed) |
565 | jiffy_wait = jiffy_wait - jiffy_elapsed; |
566 | else |
567 | jiffy_wait = 1; |
568 | |
569 | if (wait) |
570 | *wait = jiffy_wait; |
571 | return 0; |
572 | } |
573 | |
574 | static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg, |
575 | struct bio *bio, unsigned long *wait) |
576 | { |
577 | bool rw = bio_data_dir(bio); |
578 | u64 bytes_allowed, extra_bytes, tmp; |
579 | unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
580 | |
581 | jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
582 | |
583 | /* Slice has just started. Consider one slice interval */ |
584 | if (!jiffy_elapsed) |
585 | jiffy_elapsed_rnd = throtl_slice; |
586 | |
587 | jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); |
588 | |
589 | tmp = tg->bps[rw] * jiffy_elapsed_rnd; |
590 | do_div(tmp, HZ); |
591 | bytes_allowed = tmp; |
592 | |
593 | if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) { |
594 | if (wait) |
595 | *wait = 0; |
596 | return 1; |
597 | } |
598 | |
599 | /* Calc approx time to dispatch */ |
600 | extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed; |
601 | jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]); |
602 | |
603 | if (!jiffy_wait) |
604 | jiffy_wait = 1; |
605 | |
606 | /* |
607 | * This wait time is without taking into consideration the rounding |
608 | * up we did. Add that time also. |
609 | */ |
610 | jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); |
611 | if (wait) |
612 | *wait = jiffy_wait; |
613 | return 0; |
614 | } |
615 | |
616 | static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) { |
617 | if (tg->bps[rw] == -1 && tg->iops[rw] == -1) |
618 | return 1; |
619 | return 0; |
620 | } |
621 | |
622 | /* |
623 | * Returns whether one can dispatch a bio or not. Also returns approx number |
624 | * of jiffies to wait before this bio is with-in IO rate and can be dispatched |
625 | */ |
626 | static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg, |
627 | struct bio *bio, unsigned long *wait) |
628 | { |
629 | bool rw = bio_data_dir(bio); |
630 | unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; |
631 | |
632 | /* |
633 | * Currently whole state machine of group depends on first bio |
634 | * queued in the group bio list. So one should not be calling |
635 | * this function with a different bio if there are other bios |
636 | * queued. |
637 | */ |
638 | BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw])); |
639 | |
640 | /* If tg->bps = -1, then BW is unlimited */ |
641 | if (tg->bps[rw] == -1 && tg->iops[rw] == -1) { |
642 | if (wait) |
643 | *wait = 0; |
644 | return 1; |
645 | } |
646 | |
647 | /* |
648 | * If previous slice expired, start a new one otherwise renew/extend |
649 | * existing slice to make sure it is at least throtl_slice interval |
650 | * long since now. |
651 | */ |
652 | if (throtl_slice_used(td, tg, rw)) |
653 | throtl_start_new_slice(td, tg, rw); |
654 | else { |
655 | if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) |
656 | throtl_extend_slice(td, tg, rw, jiffies + throtl_slice); |
657 | } |
658 | |
659 | if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) |
660 | && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) { |
661 | if (wait) |
662 | *wait = 0; |
663 | return 1; |
664 | } |
665 | |
666 | max_wait = max(bps_wait, iops_wait); |
667 | |
668 | if (wait) |
669 | *wait = max_wait; |
670 | |
671 | if (time_before(tg->slice_end[rw], jiffies + max_wait)) |
672 | throtl_extend_slice(td, tg, rw, jiffies + max_wait); |
673 | |
674 | return 0; |
675 | } |
676 | |
677 | static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes, |
678 | int rw) |
679 | { |
680 | struct throtl_grp *tg = blkg_to_tg(blkg); |
681 | struct tg_stats_cpu *stats_cpu; |
682 | unsigned long flags; |
683 | |
684 | /* If per cpu stats are not allocated yet, don't do any accounting. */ |
685 | if (tg->stats_cpu == NULL) |
686 | return; |
687 | |
688 | /* |
689 | * Disabling interrupts to provide mutual exclusion between two |
690 | * writes on same cpu. It probably is not needed for 64bit. Not |
691 | * optimizing that case yet. |
692 | */ |
693 | local_irq_save(flags); |
694 | |
695 | stats_cpu = this_cpu_ptr(tg->stats_cpu); |
696 | |
697 | blkg_rwstat_add(&stats_cpu->serviced, rw, 1); |
698 | blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes); |
699 | |
700 | local_irq_restore(flags); |
701 | } |
702 | |
703 | static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) |
704 | { |
705 | bool rw = bio_data_dir(bio); |
706 | |
707 | /* Charge the bio to the group */ |
708 | tg->bytes_disp[rw] += bio->bi_size; |
709 | tg->io_disp[rw]++; |
710 | |
711 | throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw); |
712 | } |
713 | |
714 | static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg, |
715 | struct bio *bio) |
716 | { |
717 | bool rw = bio_data_dir(bio); |
718 | |
719 | bio_list_add(&tg->bio_lists[rw], bio); |
720 | /* Take a bio reference on tg */ |
721 | blkg_get(tg_to_blkg(tg)); |
722 | tg->nr_queued[rw]++; |
723 | td->nr_queued[rw]++; |
724 | throtl_enqueue_tg(td, tg); |
725 | } |
726 | |
727 | static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg) |
728 | { |
729 | unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
730 | struct bio *bio; |
731 | |
732 | if ((bio = bio_list_peek(&tg->bio_lists[READ]))) |
733 | tg_may_dispatch(td, tg, bio, &read_wait); |
734 | |
735 | if ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) |
736 | tg_may_dispatch(td, tg, bio, &write_wait); |
737 | |
738 | min_wait = min(read_wait, write_wait); |
739 | disptime = jiffies + min_wait; |
740 | |
741 | /* Update dispatch time */ |
742 | throtl_dequeue_tg(td, tg); |
743 | tg->disptime = disptime; |
744 | throtl_enqueue_tg(td, tg); |
745 | } |
746 | |
747 | static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg, |
748 | bool rw, struct bio_list *bl) |
749 | { |
750 | struct bio *bio; |
751 | |
752 | bio = bio_list_pop(&tg->bio_lists[rw]); |
753 | tg->nr_queued[rw]--; |
754 | /* Drop bio reference on blkg */ |
755 | blkg_put(tg_to_blkg(tg)); |
756 | |
757 | BUG_ON(td->nr_queued[rw] <= 0); |
758 | td->nr_queued[rw]--; |
759 | |
760 | throtl_charge_bio(tg, bio); |
761 | bio_list_add(bl, bio); |
762 | bio->bi_rw |= REQ_THROTTLED; |
763 | |
764 | throtl_trim_slice(td, tg, rw); |
765 | } |
766 | |
767 | static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg, |
768 | struct bio_list *bl) |
769 | { |
770 | unsigned int nr_reads = 0, nr_writes = 0; |
771 | unsigned int max_nr_reads = throtl_grp_quantum*3/4; |
772 | unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
773 | struct bio *bio; |
774 | |
775 | /* Try to dispatch 75% READS and 25% WRITES */ |
776 | |
777 | while ((bio = bio_list_peek(&tg->bio_lists[READ])) |
778 | && tg_may_dispatch(td, tg, bio, NULL)) { |
779 | |
780 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); |
781 | nr_reads++; |
782 | |
783 | if (nr_reads >= max_nr_reads) |
784 | break; |
785 | } |
786 | |
787 | while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) |
788 | && tg_may_dispatch(td, tg, bio, NULL)) { |
789 | |
790 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); |
791 | nr_writes++; |
792 | |
793 | if (nr_writes >= max_nr_writes) |
794 | break; |
795 | } |
796 | |
797 | return nr_reads + nr_writes; |
798 | } |
799 | |
800 | static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl) |
801 | { |
802 | unsigned int nr_disp = 0; |
803 | struct throtl_grp *tg; |
804 | struct throtl_rb_root *st = &td->tg_service_tree; |
805 | |
806 | while (1) { |
807 | tg = throtl_rb_first(st); |
808 | |
809 | if (!tg) |
810 | break; |
811 | |
812 | if (time_before(jiffies, tg->disptime)) |
813 | break; |
814 | |
815 | throtl_dequeue_tg(td, tg); |
816 | |
817 | nr_disp += throtl_dispatch_tg(td, tg, bl); |
818 | |
819 | if (tg->nr_queued[0] || tg->nr_queued[1]) { |
820 | tg_update_disptime(td, tg); |
821 | throtl_enqueue_tg(td, tg); |
822 | } |
823 | |
824 | if (nr_disp >= throtl_quantum) |
825 | break; |
826 | } |
827 | |
828 | return nr_disp; |
829 | } |
830 | |
831 | static void throtl_process_limit_change(struct throtl_data *td) |
832 | { |
833 | struct request_queue *q = td->queue; |
834 | struct blkcg_gq *blkg, *n; |
835 | |
836 | if (!td->limits_changed) |
837 | return; |
838 | |
839 | xchg(&td->limits_changed, false); |
840 | |
841 | throtl_log(td, "limits changed"); |
842 | |
843 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
844 | struct throtl_grp *tg = blkg_to_tg(blkg); |
845 | |
846 | if (!tg->limits_changed) |
847 | continue; |
848 | |
849 | if (!xchg(&tg->limits_changed, false)) |
850 | continue; |
851 | |
852 | throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" |
853 | " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE], |
854 | tg->iops[READ], tg->iops[WRITE]); |
855 | |
856 | /* |
857 | * Restart the slices for both READ and WRITES. It |
858 | * might happen that a group's limit are dropped |
859 | * suddenly and we don't want to account recently |
860 | * dispatched IO with new low rate |
861 | */ |
862 | throtl_start_new_slice(td, tg, 0); |
863 | throtl_start_new_slice(td, tg, 1); |
864 | |
865 | if (throtl_tg_on_rr(tg)) |
866 | tg_update_disptime(td, tg); |
867 | } |
868 | } |
869 | |
870 | /* Dispatch throttled bios. Should be called without queue lock held. */ |
871 | static int throtl_dispatch(struct request_queue *q) |
872 | { |
873 | struct throtl_data *td = q->td; |
874 | unsigned int nr_disp = 0; |
875 | struct bio_list bio_list_on_stack; |
876 | struct bio *bio; |
877 | struct blk_plug plug; |
878 | |
879 | spin_lock_irq(q->queue_lock); |
880 | |
881 | throtl_process_limit_change(td); |
882 | |
883 | if (!total_nr_queued(td)) |
884 | goto out; |
885 | |
886 | bio_list_init(&bio_list_on_stack); |
887 | |
888 | throtl_log(td, "dispatch nr_queued=%u read=%u write=%u", |
889 | total_nr_queued(td), td->nr_queued[READ], |
890 | td->nr_queued[WRITE]); |
891 | |
892 | nr_disp = throtl_select_dispatch(td, &bio_list_on_stack); |
893 | |
894 | if (nr_disp) |
895 | throtl_log(td, "bios disp=%u", nr_disp); |
896 | |
897 | throtl_schedule_next_dispatch(td); |
898 | out: |
899 | spin_unlock_irq(q->queue_lock); |
900 | |
901 | /* |
902 | * If we dispatched some requests, unplug the queue to make sure |
903 | * immediate dispatch |
904 | */ |
905 | if (nr_disp) { |
906 | blk_start_plug(&plug); |
907 | while((bio = bio_list_pop(&bio_list_on_stack))) |
908 | generic_make_request(bio); |
909 | blk_finish_plug(&plug); |
910 | } |
911 | return nr_disp; |
912 | } |
913 | |
914 | void blk_throtl_work(struct work_struct *work) |
915 | { |
916 | struct throtl_data *td = container_of(work, struct throtl_data, |
917 | throtl_work.work); |
918 | struct request_queue *q = td->queue; |
919 | |
920 | throtl_dispatch(q); |
921 | } |
922 | |
923 | /* Call with queue lock held */ |
924 | static void |
925 | throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) |
926 | { |
927 | |
928 | struct delayed_work *dwork = &td->throtl_work; |
929 | |
930 | /* schedule work if limits changed even if no bio is queued */ |
931 | if (total_nr_queued(td) || td->limits_changed) { |
932 | mod_delayed_work(kthrotld_workqueue, dwork, delay); |
933 | throtl_log(td, "schedule work. delay=%lu jiffies=%lu", |
934 | delay, jiffies); |
935 | } |
936 | } |
937 | |
938 | static u64 tg_prfill_cpu_rwstat(struct seq_file *sf, |
939 | struct blkg_policy_data *pd, int off) |
940 | { |
941 | struct throtl_grp *tg = pd_to_tg(pd); |
942 | struct blkg_rwstat rwstat = { }, tmp; |
943 | int i, cpu; |
944 | |
945 | for_each_possible_cpu(cpu) { |
946 | struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); |
947 | |
948 | tmp = blkg_rwstat_read((void *)sc + off); |
949 | for (i = 0; i < BLKG_RWSTAT_NR; i++) |
950 | rwstat.cnt[i] += tmp.cnt[i]; |
951 | } |
952 | |
953 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
954 | } |
955 | |
956 | static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft, |
957 | struct seq_file *sf) |
958 | { |
959 | struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
960 | |
961 | blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl, |
962 | cft->private, true); |
963 | return 0; |
964 | } |
965 | |
966 | static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
967 | int off) |
968 | { |
969 | struct throtl_grp *tg = pd_to_tg(pd); |
970 | u64 v = *(u64 *)((void *)tg + off); |
971 | |
972 | if (v == -1) |
973 | return 0; |
974 | return __blkg_prfill_u64(sf, pd, v); |
975 | } |
976 | |
977 | static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
978 | int off) |
979 | { |
980 | struct throtl_grp *tg = pd_to_tg(pd); |
981 | unsigned int v = *(unsigned int *)((void *)tg + off); |
982 | |
983 | if (v == -1) |
984 | return 0; |
985 | return __blkg_prfill_u64(sf, pd, v); |
986 | } |
987 | |
988 | static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
989 | struct seq_file *sf) |
990 | { |
991 | blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64, |
992 | &blkcg_policy_throtl, cft->private, false); |
993 | return 0; |
994 | } |
995 | |
996 | static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
997 | struct seq_file *sf) |
998 | { |
999 | blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint, |
1000 | &blkcg_policy_throtl, cft->private, false); |
1001 | return 0; |
1002 | } |
1003 | |
1004 | static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, |
1005 | bool is_u64) |
1006 | { |
1007 | struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
1008 | struct blkg_conf_ctx ctx; |
1009 | struct throtl_grp *tg; |
1010 | struct throtl_data *td; |
1011 | int ret; |
1012 | |
1013 | ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
1014 | if (ret) |
1015 | return ret; |
1016 | |
1017 | tg = blkg_to_tg(ctx.blkg); |
1018 | td = ctx.blkg->q->td; |
1019 | |
1020 | if (!ctx.v) |
1021 | ctx.v = -1; |
1022 | |
1023 | if (is_u64) |
1024 | *(u64 *)((void *)tg + cft->private) = ctx.v; |
1025 | else |
1026 | *(unsigned int *)((void *)tg + cft->private) = ctx.v; |
1027 | |
1028 | /* XXX: we don't need the following deferred processing */ |
1029 | xchg(&tg->limits_changed, true); |
1030 | xchg(&td->limits_changed, true); |
1031 | throtl_schedule_delayed_work(td, 0); |
1032 | |
1033 | blkg_conf_finish(&ctx); |
1034 | return 0; |
1035 | } |
1036 | |
1037 | static int tg_set_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
1038 | const char *buf) |
1039 | { |
1040 | return tg_set_conf(cgrp, cft, buf, true); |
1041 | } |
1042 | |
1043 | static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
1044 | const char *buf) |
1045 | { |
1046 | return tg_set_conf(cgrp, cft, buf, false); |
1047 | } |
1048 | |
1049 | static struct cftype throtl_files[] = { |
1050 | { |
1051 | .name = "throttle.read_bps_device", |
1052 | .private = offsetof(struct throtl_grp, bps[READ]), |
1053 | .read_seq_string = tg_print_conf_u64, |
1054 | .write_string = tg_set_conf_u64, |
1055 | .max_write_len = 256, |
1056 | }, |
1057 | { |
1058 | .name = "throttle.write_bps_device", |
1059 | .private = offsetof(struct throtl_grp, bps[WRITE]), |
1060 | .read_seq_string = tg_print_conf_u64, |
1061 | .write_string = tg_set_conf_u64, |
1062 | .max_write_len = 256, |
1063 | }, |
1064 | { |
1065 | .name = "throttle.read_iops_device", |
1066 | .private = offsetof(struct throtl_grp, iops[READ]), |
1067 | .read_seq_string = tg_print_conf_uint, |
1068 | .write_string = tg_set_conf_uint, |
1069 | .max_write_len = 256, |
1070 | }, |
1071 | { |
1072 | .name = "throttle.write_iops_device", |
1073 | .private = offsetof(struct throtl_grp, iops[WRITE]), |
1074 | .read_seq_string = tg_print_conf_uint, |
1075 | .write_string = tg_set_conf_uint, |
1076 | .max_write_len = 256, |
1077 | }, |
1078 | { |
1079 | .name = "throttle.io_service_bytes", |
1080 | .private = offsetof(struct tg_stats_cpu, service_bytes), |
1081 | .read_seq_string = tg_print_cpu_rwstat, |
1082 | }, |
1083 | { |
1084 | .name = "throttle.io_serviced", |
1085 | .private = offsetof(struct tg_stats_cpu, serviced), |
1086 | .read_seq_string = tg_print_cpu_rwstat, |
1087 | }, |
1088 | { } /* terminate */ |
1089 | }; |
1090 | |
1091 | static void throtl_shutdown_wq(struct request_queue *q) |
1092 | { |
1093 | struct throtl_data *td = q->td; |
1094 | |
1095 | cancel_delayed_work_sync(&td->throtl_work); |
1096 | } |
1097 | |
1098 | static struct blkcg_policy blkcg_policy_throtl = { |
1099 | .pd_size = sizeof(struct throtl_grp), |
1100 | .cftypes = throtl_files, |
1101 | |
1102 | .pd_init_fn = throtl_pd_init, |
1103 | .pd_exit_fn = throtl_pd_exit, |
1104 | .pd_reset_stats_fn = throtl_pd_reset_stats, |
1105 | }; |
1106 | |
1107 | bool blk_throtl_bio(struct request_queue *q, struct bio *bio) |
1108 | { |
1109 | struct throtl_data *td = q->td; |
1110 | struct throtl_grp *tg; |
1111 | bool rw = bio_data_dir(bio), update_disptime = true; |
1112 | struct blkcg *blkcg; |
1113 | bool throttled = false; |
1114 | |
1115 | if (bio->bi_rw & REQ_THROTTLED) { |
1116 | bio->bi_rw &= ~REQ_THROTTLED; |
1117 | goto out; |
1118 | } |
1119 | |
1120 | /* |
1121 | * A throtl_grp pointer retrieved under rcu can be used to access |
1122 | * basic fields like stats and io rates. If a group has no rules, |
1123 | * just update the dispatch stats in lockless manner and return. |
1124 | */ |
1125 | rcu_read_lock(); |
1126 | blkcg = bio_blkcg(bio); |
1127 | tg = throtl_lookup_tg(td, blkcg); |
1128 | if (tg) { |
1129 | if (tg_no_rule_group(tg, rw)) { |
1130 | throtl_update_dispatch_stats(tg_to_blkg(tg), |
1131 | bio->bi_size, bio->bi_rw); |
1132 | goto out_unlock_rcu; |
1133 | } |
1134 | } |
1135 | |
1136 | /* |
1137 | * Either group has not been allocated yet or it is not an unlimited |
1138 | * IO group |
1139 | */ |
1140 | spin_lock_irq(q->queue_lock); |
1141 | tg = throtl_lookup_create_tg(td, blkcg); |
1142 | if (unlikely(!tg)) |
1143 | goto out_unlock; |
1144 | |
1145 | if (tg->nr_queued[rw]) { |
1146 | /* |
1147 | * There is already another bio queued in same dir. No |
1148 | * need to update dispatch time. |
1149 | */ |
1150 | update_disptime = false; |
1151 | goto queue_bio; |
1152 | |
1153 | } |
1154 | |
1155 | /* Bio is with-in rate limit of group */ |
1156 | if (tg_may_dispatch(td, tg, bio, NULL)) { |
1157 | throtl_charge_bio(tg, bio); |
1158 | |
1159 | /* |
1160 | * We need to trim slice even when bios are not being queued |
1161 | * otherwise it might happen that a bio is not queued for |
1162 | * a long time and slice keeps on extending and trim is not |
1163 | * called for a long time. Now if limits are reduced suddenly |
1164 | * we take into account all the IO dispatched so far at new |
1165 | * low rate and * newly queued IO gets a really long dispatch |
1166 | * time. |
1167 | * |
1168 | * So keep on trimming slice even if bio is not queued. |
1169 | */ |
1170 | throtl_trim_slice(td, tg, rw); |
1171 | goto out_unlock; |
1172 | } |
1173 | |
1174 | queue_bio: |
1175 | throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu" |
1176 | " iodisp=%u iops=%u queued=%d/%d", |
1177 | rw == READ ? 'R' : 'W', |
1178 | tg->bytes_disp[rw], bio->bi_size, tg->bps[rw], |
1179 | tg->io_disp[rw], tg->iops[rw], |
1180 | tg->nr_queued[READ], tg->nr_queued[WRITE]); |
1181 | |
1182 | bio_associate_current(bio); |
1183 | throtl_add_bio_tg(q->td, tg, bio); |
1184 | throttled = true; |
1185 | |
1186 | if (update_disptime) { |
1187 | tg_update_disptime(td, tg); |
1188 | throtl_schedule_next_dispatch(td); |
1189 | } |
1190 | |
1191 | out_unlock: |
1192 | spin_unlock_irq(q->queue_lock); |
1193 | out_unlock_rcu: |
1194 | rcu_read_unlock(); |
1195 | out: |
1196 | return throttled; |
1197 | } |
1198 | |
1199 | /** |
1200 | * blk_throtl_drain - drain throttled bios |
1201 | * @q: request_queue to drain throttled bios for |
1202 | * |
1203 | * Dispatch all currently throttled bios on @q through ->make_request_fn(). |
1204 | */ |
1205 | void blk_throtl_drain(struct request_queue *q) |
1206 | __releases(q->queue_lock) __acquires(q->queue_lock) |
1207 | { |
1208 | struct throtl_data *td = q->td; |
1209 | struct throtl_rb_root *st = &td->tg_service_tree; |
1210 | struct throtl_grp *tg; |
1211 | struct bio_list bl; |
1212 | struct bio *bio; |
1213 | |
1214 | queue_lockdep_assert_held(q); |
1215 | |
1216 | bio_list_init(&bl); |
1217 | |
1218 | while ((tg = throtl_rb_first(st))) { |
1219 | throtl_dequeue_tg(td, tg); |
1220 | |
1221 | while ((bio = bio_list_peek(&tg->bio_lists[READ]))) |
1222 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
1223 | while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) |
1224 | tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
1225 | } |
1226 | spin_unlock_irq(q->queue_lock); |
1227 | |
1228 | while ((bio = bio_list_pop(&bl))) |
1229 | generic_make_request(bio); |
1230 | |
1231 | spin_lock_irq(q->queue_lock); |
1232 | } |
1233 | |
1234 | int blk_throtl_init(struct request_queue *q) |
1235 | { |
1236 | struct throtl_data *td; |
1237 | int ret; |
1238 | |
1239 | td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); |
1240 | if (!td) |
1241 | return -ENOMEM; |
1242 | |
1243 | td->tg_service_tree = THROTL_RB_ROOT; |
1244 | td->limits_changed = false; |
1245 | INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); |
1246 | |
1247 | q->td = td; |
1248 | td->queue = q; |
1249 | |
1250 | /* activate policy */ |
1251 | ret = blkcg_activate_policy(q, &blkcg_policy_throtl); |
1252 | if (ret) |
1253 | kfree(td); |
1254 | return ret; |
1255 | } |
1256 | |
1257 | void blk_throtl_exit(struct request_queue *q) |
1258 | { |
1259 | BUG_ON(!q->td); |
1260 | throtl_shutdown_wq(q); |
1261 | blkcg_deactivate_policy(q, &blkcg_policy_throtl); |
1262 | kfree(q->td); |
1263 | } |
1264 | |
1265 | static int __init throtl_init(void) |
1266 | { |
1267 | kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
1268 | if (!kthrotld_workqueue) |
1269 | panic("Failed to create kthrotld\n"); |
1270 | |
1271 | return blkcg_policy_register(&blkcg_policy_throtl); |
1272 | } |
1273 | |
1274 | module_init(throtl_init); |
1275 |
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Tags:
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od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
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