2 * Interface for controlling IO bandwidth on a request queue
4 * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com>
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"
15 /* Max dispatch from a group in 1 round */
16 static int throtl_grp_quantum
= 8;
18 /* Total max dispatch from all groups in one round */
19 static int throtl_quantum
= 32;
21 /* Throttling is performed over 100ms slice and after that slice is renewed */
22 static unsigned long throtl_slice
= HZ
/10; /* 100 ms */
24 static struct blkcg_policy blkcg_policy_throtl
;
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
,
31 struct throtl_rb_root
{
35 unsigned long min_disptime
;
38 #define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
39 .count = 0, .min_disptime = 0}
41 #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
43 /* Per-cpu group stats */
45 /* total bytes transferred */
46 struct blkg_rwstat service_bytes
;
47 /* total IOs serviced, post merge */
48 struct blkg_rwstat serviced
;
52 /* must be the first member */
53 struct blkg_policy_data pd
;
55 /* active throtl group service_tree member */
56 struct rb_node rb_node
;
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.
63 unsigned long disptime
;
67 /* Two lists for READ and WRITE */
68 struct bio_list bio_lists
[2];
70 /* Number of queued bios on READ and WRITE lists */
71 unsigned int nr_queued
[2];
73 /* bytes per second rate limits */
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];
84 /* When did we start a new slice */
85 unsigned long slice_start
[2];
86 unsigned long slice_end
[2];
88 /* Per cpu stats pointer */
89 struct tg_stats_cpu __percpu
*stats_cpu
;
91 /* List of tgs waiting for per cpu stats memory to be allocated */
92 struct list_head stats_alloc_node
;
97 /* service tree for active throtl groups */
98 struct throtl_rb_root tg_service_tree
;
100 struct request_queue
*queue
;
102 /* Total Number of queued bios on READ and WRITE lists */
103 unsigned int nr_queued
[2];
106 * number of total undestroyed groups
108 unsigned int nr_undestroyed_grps
;
110 /* Work for dispatching throttled bios */
111 struct delayed_work dispatch_work
;
114 /* list and work item to allocate percpu group stats */
115 static DEFINE_SPINLOCK(tg_stats_alloc_lock
);
116 static LIST_HEAD(tg_stats_alloc_list
);
118 static void tg_stats_alloc_fn(struct work_struct
*);
119 static DECLARE_DELAYED_WORK(tg_stats_alloc_work
, tg_stats_alloc_fn
);
121 static inline struct throtl_grp
*pd_to_tg(struct blkg_policy_data
*pd
)
123 return pd
? container_of(pd
, struct throtl_grp
, pd
) : NULL
;
126 static inline struct throtl_grp
*blkg_to_tg(struct blkcg_gq
*blkg
)
128 return pd_to_tg(blkg_to_pd(blkg
, &blkcg_policy_throtl
));
131 static inline struct blkcg_gq
*tg_to_blkg(struct throtl_grp
*tg
)
133 return pd_to_blkg(&tg
->pd
);
136 static inline struct throtl_grp
*td_root_tg(struct throtl_data
*td
)
138 return blkg_to_tg(td
->queue
->root_blkg
);
141 enum tg_state_flags
{
142 THROTL_TG_FLAG_on_rr
= 0, /* on round-robin busy list */
145 #define THROTL_TG_FNS(name) \
146 static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
148 (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
150 static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
152 (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
154 static inline int throtl_tg_##name(const struct throtl_grp *tg) \
156 return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
159 THROTL_TG_FNS(on_rr
);
161 #define throtl_log_tg(td, tg, fmt, args...) do { \
164 blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf)); \
165 blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \
168 #define throtl_log(td, fmt, args...) \
169 blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
171 static inline unsigned int total_nr_queued(struct throtl_data
*td
)
173 return td
->nr_queued
[0] + td
->nr_queued
[1];
177 * Worker for allocating per cpu stat for tgs. This is scheduled on the
178 * system_wq once there are some groups on the alloc_list waiting for
181 static void tg_stats_alloc_fn(struct work_struct
*work
)
183 static struct tg_stats_cpu
*stats_cpu
; /* this fn is non-reentrant */
184 struct delayed_work
*dwork
= to_delayed_work(work
);
189 stats_cpu
= alloc_percpu(struct tg_stats_cpu
);
191 /* allocation failed, try again after some time */
192 schedule_delayed_work(dwork
, msecs_to_jiffies(10));
197 spin_lock_irq(&tg_stats_alloc_lock
);
199 if (!list_empty(&tg_stats_alloc_list
)) {
200 struct throtl_grp
*tg
= list_first_entry(&tg_stats_alloc_list
,
203 swap(tg
->stats_cpu
, stats_cpu
);
204 list_del_init(&tg
->stats_alloc_node
);
207 empty
= list_empty(&tg_stats_alloc_list
);
208 spin_unlock_irq(&tg_stats_alloc_lock
);
213 static void throtl_pd_init(struct blkcg_gq
*blkg
)
215 struct throtl_grp
*tg
= blkg_to_tg(blkg
);
218 RB_CLEAR_NODE(&tg
->rb_node
);
219 bio_list_init(&tg
->bio_lists
[0]);
220 bio_list_init(&tg
->bio_lists
[1]);
225 tg
->iops
[WRITE
] = -1;
228 * Ugh... We need to perform per-cpu allocation for tg->stats_cpu
229 * but percpu allocator can't be called from IO path. Queue tg on
230 * tg_stats_alloc_list and allocate from work item.
232 spin_lock_irqsave(&tg_stats_alloc_lock
, flags
);
233 list_add(&tg
->stats_alloc_node
, &tg_stats_alloc_list
);
234 schedule_delayed_work(&tg_stats_alloc_work
, 0);
235 spin_unlock_irqrestore(&tg_stats_alloc_lock
, flags
);
238 static void throtl_pd_exit(struct blkcg_gq
*blkg
)
240 struct throtl_grp
*tg
= blkg_to_tg(blkg
);
243 spin_lock_irqsave(&tg_stats_alloc_lock
, flags
);
244 list_del_init(&tg
->stats_alloc_node
);
245 spin_unlock_irqrestore(&tg_stats_alloc_lock
, flags
);
247 free_percpu(tg
->stats_cpu
);
250 static void throtl_pd_reset_stats(struct blkcg_gq
*blkg
)
252 struct throtl_grp
*tg
= blkg_to_tg(blkg
);
255 if (tg
->stats_cpu
== NULL
)
258 for_each_possible_cpu(cpu
) {
259 struct tg_stats_cpu
*sc
= per_cpu_ptr(tg
->stats_cpu
, cpu
);
261 blkg_rwstat_reset(&sc
->service_bytes
);
262 blkg_rwstat_reset(&sc
->serviced
);
266 static struct throtl_grp
*throtl_lookup_tg(struct throtl_data
*td
,
270 * This is the common case when there are no blkcgs. Avoid lookup
273 if (blkcg
== &blkcg_root
)
274 return td_root_tg(td
);
276 return blkg_to_tg(blkg_lookup(blkcg
, td
->queue
));
279 static struct throtl_grp
*throtl_lookup_create_tg(struct throtl_data
*td
,
282 struct request_queue
*q
= td
->queue
;
283 struct throtl_grp
*tg
= NULL
;
286 * This is the common case when there are no blkcgs. Avoid lookup
289 if (blkcg
== &blkcg_root
) {
292 struct blkcg_gq
*blkg
;
294 blkg
= blkg_lookup_create(blkcg
, q
);
296 /* if %NULL and @q is alive, fall back to root_tg */
298 tg
= blkg_to_tg(blkg
);
299 else if (!blk_queue_dying(q
))
306 static struct throtl_grp
*throtl_rb_first(struct throtl_rb_root
*root
)
308 /* Service tree is empty */
313 root
->left
= rb_first(&root
->rb
);
316 return rb_entry_tg(root
->left
);
321 static void rb_erase_init(struct rb_node
*n
, struct rb_root
*root
)
327 static void throtl_rb_erase(struct rb_node
*n
, struct throtl_rb_root
*root
)
331 rb_erase_init(n
, &root
->rb
);
335 static void update_min_dispatch_time(struct throtl_rb_root
*st
)
337 struct throtl_grp
*tg
;
339 tg
= throtl_rb_first(st
);
343 st
->min_disptime
= tg
->disptime
;
347 tg_service_tree_add(struct throtl_rb_root
*st
, struct throtl_grp
*tg
)
349 struct rb_node
**node
= &st
->rb
.rb_node
;
350 struct rb_node
*parent
= NULL
;
351 struct throtl_grp
*__tg
;
352 unsigned long key
= tg
->disptime
;
355 while (*node
!= NULL
) {
357 __tg
= rb_entry_tg(parent
);
359 if (time_before(key
, __tg
->disptime
))
360 node
= &parent
->rb_left
;
362 node
= &parent
->rb_right
;
368 st
->left
= &tg
->rb_node
;
370 rb_link_node(&tg
->rb_node
, parent
, node
);
371 rb_insert_color(&tg
->rb_node
, &st
->rb
);
374 static void __throtl_enqueue_tg(struct throtl_data
*td
, struct throtl_grp
*tg
)
376 struct throtl_rb_root
*st
= &td
->tg_service_tree
;
378 tg_service_tree_add(st
, tg
);
379 throtl_mark_tg_on_rr(tg
);
383 static void throtl_enqueue_tg(struct throtl_data
*td
, struct throtl_grp
*tg
)
385 if (!throtl_tg_on_rr(tg
))
386 __throtl_enqueue_tg(td
, tg
);
389 static void __throtl_dequeue_tg(struct throtl_data
*td
, struct throtl_grp
*tg
)
391 throtl_rb_erase(&tg
->rb_node
, &td
->tg_service_tree
);
392 throtl_clear_tg_on_rr(tg
);
395 static void throtl_dequeue_tg(struct throtl_data
*td
, struct throtl_grp
*tg
)
397 if (throtl_tg_on_rr(tg
))
398 __throtl_dequeue_tg(td
, tg
);
401 static void throtl_schedule_next_dispatch(struct throtl_data
*td
)
403 struct throtl_rb_root
*st
= &td
->tg_service_tree
;
406 * If there are more bios pending, schedule more work.
408 if (!total_nr_queued(td
))
413 update_min_dispatch_time(st
);
415 if (time_before_eq(st
->min_disptime
, jiffies
))
416 throtl_schedule_delayed_work(td
, 0);
418 throtl_schedule_delayed_work(td
, (st
->min_disptime
- jiffies
));
422 throtl_start_new_slice(struct throtl_data
*td
, struct throtl_grp
*tg
, bool rw
)
424 tg
->bytes_disp
[rw
] = 0;
426 tg
->slice_start
[rw
] = jiffies
;
427 tg
->slice_end
[rw
] = jiffies
+ throtl_slice
;
428 throtl_log_tg(td
, tg
, "[%c] new slice start=%lu end=%lu jiffies=%lu",
429 rw
== READ
? 'R' : 'W', tg
->slice_start
[rw
],
430 tg
->slice_end
[rw
], jiffies
);
433 static inline void throtl_set_slice_end(struct throtl_data
*td
,
434 struct throtl_grp
*tg
, bool rw
, unsigned long jiffy_end
)
436 tg
->slice_end
[rw
] = roundup(jiffy_end
, throtl_slice
);
439 static inline void throtl_extend_slice(struct throtl_data
*td
,
440 struct throtl_grp
*tg
, bool rw
, unsigned long jiffy_end
)
442 tg
->slice_end
[rw
] = roundup(jiffy_end
, throtl_slice
);
443 throtl_log_tg(td
, tg
, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
444 rw
== READ
? 'R' : 'W', tg
->slice_start
[rw
],
445 tg
->slice_end
[rw
], jiffies
);
448 /* Determine if previously allocated or extended slice is complete or not */
450 throtl_slice_used(struct throtl_data
*td
, struct throtl_grp
*tg
, bool rw
)
452 if (time_in_range(jiffies
, tg
->slice_start
[rw
], tg
->slice_end
[rw
]))
458 /* Trim the used slices and adjust slice start accordingly */
460 throtl_trim_slice(struct throtl_data
*td
, struct throtl_grp
*tg
, bool rw
)
462 unsigned long nr_slices
, time_elapsed
, io_trim
;
465 BUG_ON(time_before(tg
->slice_end
[rw
], tg
->slice_start
[rw
]));
468 * If bps are unlimited (-1), then time slice don't get
469 * renewed. Don't try to trim the slice if slice is used. A new
470 * slice will start when appropriate.
472 if (throtl_slice_used(td
, tg
, rw
))
476 * A bio has been dispatched. Also adjust slice_end. It might happen
477 * that initially cgroup limit was very low resulting in high
478 * slice_end, but later limit was bumped up and bio was dispached
479 * sooner, then we need to reduce slice_end. A high bogus slice_end
480 * is bad because it does not allow new slice to start.
483 throtl_set_slice_end(td
, tg
, rw
, jiffies
+ throtl_slice
);
485 time_elapsed
= jiffies
- tg
->slice_start
[rw
];
487 nr_slices
= time_elapsed
/ throtl_slice
;
491 tmp
= tg
->bps
[rw
] * throtl_slice
* nr_slices
;
495 io_trim
= (tg
->iops
[rw
] * throtl_slice
* nr_slices
)/HZ
;
497 if (!bytes_trim
&& !io_trim
)
500 if (tg
->bytes_disp
[rw
] >= bytes_trim
)
501 tg
->bytes_disp
[rw
] -= bytes_trim
;
503 tg
->bytes_disp
[rw
] = 0;
505 if (tg
->io_disp
[rw
] >= io_trim
)
506 tg
->io_disp
[rw
] -= io_trim
;
510 tg
->slice_start
[rw
] += nr_slices
* throtl_slice
;
512 throtl_log_tg(td
, tg
, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
513 " start=%lu end=%lu jiffies=%lu",
514 rw
== READ
? 'R' : 'W', nr_slices
, bytes_trim
, io_trim
,
515 tg
->slice_start
[rw
], tg
->slice_end
[rw
], jiffies
);
518 static bool tg_with_in_iops_limit(struct throtl_data
*td
, struct throtl_grp
*tg
,
519 struct bio
*bio
, unsigned long *wait
)
521 bool rw
= bio_data_dir(bio
);
522 unsigned int io_allowed
;
523 unsigned long jiffy_elapsed
, jiffy_wait
, jiffy_elapsed_rnd
;
526 jiffy_elapsed
= jiffy_elapsed_rnd
= jiffies
- tg
->slice_start
[rw
];
528 /* Slice has just started. Consider one slice interval */
530 jiffy_elapsed_rnd
= throtl_slice
;
532 jiffy_elapsed_rnd
= roundup(jiffy_elapsed_rnd
, throtl_slice
);
535 * jiffy_elapsed_rnd should not be a big value as minimum iops can be
536 * 1 then at max jiffy elapsed should be equivalent of 1 second as we
537 * will allow dispatch after 1 second and after that slice should
541 tmp
= (u64
)tg
->iops
[rw
] * jiffy_elapsed_rnd
;
545 io_allowed
= UINT_MAX
;
549 if (tg
->io_disp
[rw
] + 1 <= io_allowed
) {
555 /* Calc approx time to dispatch */
556 jiffy_wait
= ((tg
->io_disp
[rw
] + 1) * HZ
)/tg
->iops
[rw
] + 1;
558 if (jiffy_wait
> jiffy_elapsed
)
559 jiffy_wait
= jiffy_wait
- jiffy_elapsed
;
568 static bool tg_with_in_bps_limit(struct throtl_data
*td
, struct throtl_grp
*tg
,
569 struct bio
*bio
, unsigned long *wait
)
571 bool rw
= bio_data_dir(bio
);
572 u64 bytes_allowed
, extra_bytes
, tmp
;
573 unsigned long jiffy_elapsed
, jiffy_wait
, jiffy_elapsed_rnd
;
575 jiffy_elapsed
= jiffy_elapsed_rnd
= jiffies
- tg
->slice_start
[rw
];
577 /* Slice has just started. Consider one slice interval */
579 jiffy_elapsed_rnd
= throtl_slice
;
581 jiffy_elapsed_rnd
= roundup(jiffy_elapsed_rnd
, throtl_slice
);
583 tmp
= tg
->bps
[rw
] * jiffy_elapsed_rnd
;
587 if (tg
->bytes_disp
[rw
] + bio
->bi_size
<= bytes_allowed
) {
593 /* Calc approx time to dispatch */
594 extra_bytes
= tg
->bytes_disp
[rw
] + bio
->bi_size
- bytes_allowed
;
595 jiffy_wait
= div64_u64(extra_bytes
* HZ
, tg
->bps
[rw
]);
601 * This wait time is without taking into consideration the rounding
602 * up we did. Add that time also.
604 jiffy_wait
= jiffy_wait
+ (jiffy_elapsed_rnd
- jiffy_elapsed
);
610 static bool tg_no_rule_group(struct throtl_grp
*tg
, bool rw
) {
611 if (tg
->bps
[rw
] == -1 && tg
->iops
[rw
] == -1)
617 * Returns whether one can dispatch a bio or not. Also returns approx number
618 * of jiffies to wait before this bio is with-in IO rate and can be dispatched
620 static bool tg_may_dispatch(struct throtl_data
*td
, struct throtl_grp
*tg
,
621 struct bio
*bio
, unsigned long *wait
)
623 bool rw
= bio_data_dir(bio
);
624 unsigned long bps_wait
= 0, iops_wait
= 0, max_wait
= 0;
627 * Currently whole state machine of group depends on first bio
628 * queued in the group bio list. So one should not be calling
629 * this function with a different bio if there are other bios
632 BUG_ON(tg
->nr_queued
[rw
] && bio
!= bio_list_peek(&tg
->bio_lists
[rw
]));
634 /* If tg->bps = -1, then BW is unlimited */
635 if (tg
->bps
[rw
] == -1 && tg
->iops
[rw
] == -1) {
642 * If previous slice expired, start a new one otherwise renew/extend
643 * existing slice to make sure it is at least throtl_slice interval
646 if (throtl_slice_used(td
, tg
, rw
))
647 throtl_start_new_slice(td
, tg
, rw
);
649 if (time_before(tg
->slice_end
[rw
], jiffies
+ throtl_slice
))
650 throtl_extend_slice(td
, tg
, rw
, jiffies
+ throtl_slice
);
653 if (tg_with_in_bps_limit(td
, tg
, bio
, &bps_wait
)
654 && tg_with_in_iops_limit(td
, tg
, bio
, &iops_wait
)) {
660 max_wait
= max(bps_wait
, iops_wait
);
665 if (time_before(tg
->slice_end
[rw
], jiffies
+ max_wait
))
666 throtl_extend_slice(td
, tg
, rw
, jiffies
+ max_wait
);
671 static void throtl_update_dispatch_stats(struct blkcg_gq
*blkg
, u64 bytes
,
674 struct throtl_grp
*tg
= blkg_to_tg(blkg
);
675 struct tg_stats_cpu
*stats_cpu
;
678 /* If per cpu stats are not allocated yet, don't do any accounting. */
679 if (tg
->stats_cpu
== NULL
)
683 * Disabling interrupts to provide mutual exclusion between two
684 * writes on same cpu. It probably is not needed for 64bit. Not
685 * optimizing that case yet.
687 local_irq_save(flags
);
689 stats_cpu
= this_cpu_ptr(tg
->stats_cpu
);
691 blkg_rwstat_add(&stats_cpu
->serviced
, rw
, 1);
692 blkg_rwstat_add(&stats_cpu
->service_bytes
, rw
, bytes
);
694 local_irq_restore(flags
);
697 static void throtl_charge_bio(struct throtl_grp
*tg
, struct bio
*bio
)
699 bool rw
= bio_data_dir(bio
);
701 /* Charge the bio to the group */
702 tg
->bytes_disp
[rw
] += bio
->bi_size
;
705 throtl_update_dispatch_stats(tg_to_blkg(tg
), bio
->bi_size
, bio
->bi_rw
);
708 static void throtl_add_bio_tg(struct throtl_data
*td
, struct throtl_grp
*tg
,
711 bool rw
= bio_data_dir(bio
);
713 bio_list_add(&tg
->bio_lists
[rw
], bio
);
714 /* Take a bio reference on tg */
715 blkg_get(tg_to_blkg(tg
));
718 throtl_enqueue_tg(td
, tg
);
721 static void tg_update_disptime(struct throtl_data
*td
, struct throtl_grp
*tg
)
723 unsigned long read_wait
= -1, write_wait
= -1, min_wait
= -1, disptime
;
726 if ((bio
= bio_list_peek(&tg
->bio_lists
[READ
])))
727 tg_may_dispatch(td
, tg
, bio
, &read_wait
);
729 if ((bio
= bio_list_peek(&tg
->bio_lists
[WRITE
])))
730 tg_may_dispatch(td
, tg
, bio
, &write_wait
);
732 min_wait
= min(read_wait
, write_wait
);
733 disptime
= jiffies
+ min_wait
;
735 /* Update dispatch time */
736 throtl_dequeue_tg(td
, tg
);
737 tg
->disptime
= disptime
;
738 throtl_enqueue_tg(td
, tg
);
741 static void tg_dispatch_one_bio(struct throtl_data
*td
, struct throtl_grp
*tg
,
742 bool rw
, struct bio_list
*bl
)
746 bio
= bio_list_pop(&tg
->bio_lists
[rw
]);
748 /* Drop bio reference on blkg */
749 blkg_put(tg_to_blkg(tg
));
751 BUG_ON(td
->nr_queued
[rw
] <= 0);
754 throtl_charge_bio(tg
, bio
);
755 bio_list_add(bl
, bio
);
756 bio
->bi_rw
|= REQ_THROTTLED
;
758 throtl_trim_slice(td
, tg
, rw
);
761 static int throtl_dispatch_tg(struct throtl_data
*td
, struct throtl_grp
*tg
,
764 unsigned int nr_reads
= 0, nr_writes
= 0;
765 unsigned int max_nr_reads
= throtl_grp_quantum
*3/4;
766 unsigned int max_nr_writes
= throtl_grp_quantum
- max_nr_reads
;
769 /* Try to dispatch 75% READS and 25% WRITES */
771 while ((bio
= bio_list_peek(&tg
->bio_lists
[READ
]))
772 && tg_may_dispatch(td
, tg
, bio
, NULL
)) {
774 tg_dispatch_one_bio(td
, tg
, bio_data_dir(bio
), bl
);
777 if (nr_reads
>= max_nr_reads
)
781 while ((bio
= bio_list_peek(&tg
->bio_lists
[WRITE
]))
782 && tg_may_dispatch(td
, tg
, bio
, NULL
)) {
784 tg_dispatch_one_bio(td
, tg
, bio_data_dir(bio
), bl
);
787 if (nr_writes
>= max_nr_writes
)
791 return nr_reads
+ nr_writes
;
794 static int throtl_select_dispatch(struct throtl_data
*td
, struct bio_list
*bl
)
796 unsigned int nr_disp
= 0;
797 struct throtl_grp
*tg
;
798 struct throtl_rb_root
*st
= &td
->tg_service_tree
;
801 tg
= throtl_rb_first(st
);
806 if (time_before(jiffies
, tg
->disptime
))
809 throtl_dequeue_tg(td
, tg
);
811 nr_disp
+= throtl_dispatch_tg(td
, tg
, bl
);
813 if (tg
->nr_queued
[0] || tg
->nr_queued
[1])
814 tg_update_disptime(td
, tg
);
816 if (nr_disp
>= throtl_quantum
)
823 /* work function to dispatch throttled bios */
824 void blk_throtl_dispatch_work_fn(struct work_struct
*work
)
826 struct throtl_data
*td
= container_of(to_delayed_work(work
),
827 struct throtl_data
, dispatch_work
);
828 struct request_queue
*q
= td
->queue
;
829 unsigned int nr_disp
= 0;
830 struct bio_list bio_list_on_stack
;
832 struct blk_plug plug
;
834 spin_lock_irq(q
->queue_lock
);
836 if (!total_nr_queued(td
))
839 bio_list_init(&bio_list_on_stack
);
841 throtl_log(td
, "dispatch nr_queued=%u read=%u write=%u",
842 total_nr_queued(td
), td
->nr_queued
[READ
],
843 td
->nr_queued
[WRITE
]);
845 nr_disp
= throtl_select_dispatch(td
, &bio_list_on_stack
);
848 throtl_log(td
, "bios disp=%u", nr_disp
);
850 throtl_schedule_next_dispatch(td
);
852 spin_unlock_irq(q
->queue_lock
);
855 * If we dispatched some requests, unplug the queue to make sure
859 blk_start_plug(&plug
);
860 while((bio
= bio_list_pop(&bio_list_on_stack
)))
861 generic_make_request(bio
);
862 blk_finish_plug(&plug
);
866 /* Call with queue lock held */
868 throtl_schedule_delayed_work(struct throtl_data
*td
, unsigned long delay
)
871 struct delayed_work
*dwork
= &td
->dispatch_work
;
873 if (total_nr_queued(td
)) {
874 mod_delayed_work(kthrotld_workqueue
, dwork
, delay
);
875 throtl_log(td
, "schedule work. delay=%lu jiffies=%lu",
880 static u64
tg_prfill_cpu_rwstat(struct seq_file
*sf
,
881 struct blkg_policy_data
*pd
, int off
)
883 struct throtl_grp
*tg
= pd_to_tg(pd
);
884 struct blkg_rwstat rwstat
= { }, tmp
;
887 for_each_possible_cpu(cpu
) {
888 struct tg_stats_cpu
*sc
= per_cpu_ptr(tg
->stats_cpu
, cpu
);
890 tmp
= blkg_rwstat_read((void *)sc
+ off
);
891 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
892 rwstat
.cnt
[i
] += tmp
.cnt
[i
];
895 return __blkg_prfill_rwstat(sf
, pd
, &rwstat
);
898 static int tg_print_cpu_rwstat(struct cgroup
*cgrp
, struct cftype
*cft
,
901 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
903 blkcg_print_blkgs(sf
, blkcg
, tg_prfill_cpu_rwstat
, &blkcg_policy_throtl
,
908 static u64
tg_prfill_conf_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
911 struct throtl_grp
*tg
= pd_to_tg(pd
);
912 u64 v
= *(u64
*)((void *)tg
+ off
);
916 return __blkg_prfill_u64(sf
, pd
, v
);
919 static u64
tg_prfill_conf_uint(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
922 struct throtl_grp
*tg
= pd_to_tg(pd
);
923 unsigned int v
= *(unsigned int *)((void *)tg
+ off
);
927 return __blkg_prfill_u64(sf
, pd
, v
);
930 static int tg_print_conf_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
933 blkcg_print_blkgs(sf
, cgroup_to_blkcg(cgrp
), tg_prfill_conf_u64
,
934 &blkcg_policy_throtl
, cft
->private, false);
938 static int tg_print_conf_uint(struct cgroup
*cgrp
, struct cftype
*cft
,
941 blkcg_print_blkgs(sf
, cgroup_to_blkcg(cgrp
), tg_prfill_conf_uint
,
942 &blkcg_policy_throtl
, cft
->private, false);
946 static int tg_set_conf(struct cgroup
*cgrp
, struct cftype
*cft
, const char *buf
,
949 struct blkcg
*blkcg
= cgroup_to_blkcg(cgrp
);
950 struct blkg_conf_ctx ctx
;
951 struct throtl_grp
*tg
;
952 struct throtl_data
*td
;
955 ret
= blkg_conf_prep(blkcg
, &blkcg_policy_throtl
, buf
, &ctx
);
959 tg
= blkg_to_tg(ctx
.blkg
);
960 td
= ctx
.blkg
->q
->td
;
966 *(u64
*)((void *)tg
+ cft
->private) = ctx
.v
;
968 *(unsigned int *)((void *)tg
+ cft
->private) = ctx
.v
;
970 throtl_log_tg(td
, tg
, "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
971 tg
->bps
[READ
], tg
->bps
[WRITE
],
972 tg
->iops
[READ
], tg
->iops
[WRITE
]);
975 * We're already holding queue_lock and know @tg is valid. Let's
976 * apply the new config directly.
978 * Restart the slices for both READ and WRITES. It might happen
979 * that a group's limit are dropped suddenly and we don't want to
980 * account recently dispatched IO with new low rate.
982 throtl_start_new_slice(td
, tg
, 0);
983 throtl_start_new_slice(td
, tg
, 1);
985 if (throtl_tg_on_rr(tg
)) {
986 tg_update_disptime(td
, tg
);
987 throtl_schedule_next_dispatch(td
);
990 blkg_conf_finish(&ctx
);
994 static int tg_set_conf_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
997 return tg_set_conf(cgrp
, cft
, buf
, true);
1000 static int tg_set_conf_uint(struct cgroup
*cgrp
, struct cftype
*cft
,
1003 return tg_set_conf(cgrp
, cft
, buf
, false);
1006 static struct cftype throtl_files
[] = {
1008 .name
= "throttle.read_bps_device",
1009 .private = offsetof(struct throtl_grp
, bps
[READ
]),
1010 .read_seq_string
= tg_print_conf_u64
,
1011 .write_string
= tg_set_conf_u64
,
1012 .max_write_len
= 256,
1015 .name
= "throttle.write_bps_device",
1016 .private = offsetof(struct throtl_grp
, bps
[WRITE
]),
1017 .read_seq_string
= tg_print_conf_u64
,
1018 .write_string
= tg_set_conf_u64
,
1019 .max_write_len
= 256,
1022 .name
= "throttle.read_iops_device",
1023 .private = offsetof(struct throtl_grp
, iops
[READ
]),
1024 .read_seq_string
= tg_print_conf_uint
,
1025 .write_string
= tg_set_conf_uint
,
1026 .max_write_len
= 256,
1029 .name
= "throttle.write_iops_device",
1030 .private = offsetof(struct throtl_grp
, iops
[WRITE
]),
1031 .read_seq_string
= tg_print_conf_uint
,
1032 .write_string
= tg_set_conf_uint
,
1033 .max_write_len
= 256,
1036 .name
= "throttle.io_service_bytes",
1037 .private = offsetof(struct tg_stats_cpu
, service_bytes
),
1038 .read_seq_string
= tg_print_cpu_rwstat
,
1041 .name
= "throttle.io_serviced",
1042 .private = offsetof(struct tg_stats_cpu
, serviced
),
1043 .read_seq_string
= tg_print_cpu_rwstat
,
1048 static void throtl_shutdown_wq(struct request_queue
*q
)
1050 struct throtl_data
*td
= q
->td
;
1052 cancel_delayed_work_sync(&td
->dispatch_work
);
1055 static struct blkcg_policy blkcg_policy_throtl
= {
1056 .pd_size
= sizeof(struct throtl_grp
),
1057 .cftypes
= throtl_files
,
1059 .pd_init_fn
= throtl_pd_init
,
1060 .pd_exit_fn
= throtl_pd_exit
,
1061 .pd_reset_stats_fn
= throtl_pd_reset_stats
,
1064 bool blk_throtl_bio(struct request_queue
*q
, struct bio
*bio
)
1066 struct throtl_data
*td
= q
->td
;
1067 struct throtl_grp
*tg
;
1068 bool rw
= bio_data_dir(bio
), update_disptime
= true;
1069 struct blkcg
*blkcg
;
1070 bool throttled
= false;
1072 if (bio
->bi_rw
& REQ_THROTTLED
) {
1073 bio
->bi_rw
&= ~REQ_THROTTLED
;
1078 * A throtl_grp pointer retrieved under rcu can be used to access
1079 * basic fields like stats and io rates. If a group has no rules,
1080 * just update the dispatch stats in lockless manner and return.
1083 blkcg
= bio_blkcg(bio
);
1084 tg
= throtl_lookup_tg(td
, blkcg
);
1086 if (tg_no_rule_group(tg
, rw
)) {
1087 throtl_update_dispatch_stats(tg_to_blkg(tg
),
1088 bio
->bi_size
, bio
->bi_rw
);
1089 goto out_unlock_rcu
;
1094 * Either group has not been allocated yet or it is not an unlimited
1097 spin_lock_irq(q
->queue_lock
);
1098 tg
= throtl_lookup_create_tg(td
, blkcg
);
1102 if (tg
->nr_queued
[rw
]) {
1104 * There is already another bio queued in same dir. No
1105 * need to update dispatch time.
1107 update_disptime
= false;
1112 /* Bio is with-in rate limit of group */
1113 if (tg_may_dispatch(td
, tg
, bio
, NULL
)) {
1114 throtl_charge_bio(tg
, bio
);
1117 * We need to trim slice even when bios are not being queued
1118 * otherwise it might happen that a bio is not queued for
1119 * a long time and slice keeps on extending and trim is not
1120 * called for a long time. Now if limits are reduced suddenly
1121 * we take into account all the IO dispatched so far at new
1122 * low rate and * newly queued IO gets a really long dispatch
1125 * So keep on trimming slice even if bio is not queued.
1127 throtl_trim_slice(td
, tg
, rw
);
1132 throtl_log_tg(td
, tg
, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
1133 " iodisp=%u iops=%u queued=%d/%d",
1134 rw
== READ
? 'R' : 'W',
1135 tg
->bytes_disp
[rw
], bio
->bi_size
, tg
->bps
[rw
],
1136 tg
->io_disp
[rw
], tg
->iops
[rw
],
1137 tg
->nr_queued
[READ
], tg
->nr_queued
[WRITE
]);
1139 bio_associate_current(bio
);
1140 throtl_add_bio_tg(q
->td
, tg
, bio
);
1143 if (update_disptime
) {
1144 tg_update_disptime(td
, tg
);
1145 throtl_schedule_next_dispatch(td
);
1149 spin_unlock_irq(q
->queue_lock
);
1157 * blk_throtl_drain - drain throttled bios
1158 * @q: request_queue to drain throttled bios for
1160 * Dispatch all currently throttled bios on @q through ->make_request_fn().
1162 void blk_throtl_drain(struct request_queue
*q
)
1163 __releases(q
->queue_lock
) __acquires(q
->queue_lock
)
1165 struct throtl_data
*td
= q
->td
;
1166 struct throtl_rb_root
*st
= &td
->tg_service_tree
;
1167 struct throtl_grp
*tg
;
1171 queue_lockdep_assert_held(q
);
1175 while ((tg
= throtl_rb_first(st
))) {
1176 throtl_dequeue_tg(td
, tg
);
1178 while ((bio
= bio_list_peek(&tg
->bio_lists
[READ
])))
1179 tg_dispatch_one_bio(td
, tg
, bio_data_dir(bio
), &bl
);
1180 while ((bio
= bio_list_peek(&tg
->bio_lists
[WRITE
])))
1181 tg_dispatch_one_bio(td
, tg
, bio_data_dir(bio
), &bl
);
1183 spin_unlock_irq(q
->queue_lock
);
1185 while ((bio
= bio_list_pop(&bl
)))
1186 generic_make_request(bio
);
1188 spin_lock_irq(q
->queue_lock
);
1191 int blk_throtl_init(struct request_queue
*q
)
1193 struct throtl_data
*td
;
1196 td
= kzalloc_node(sizeof(*td
), GFP_KERNEL
, q
->node
);
1200 td
->tg_service_tree
= THROTL_RB_ROOT
;
1201 INIT_DELAYED_WORK(&td
->dispatch_work
, blk_throtl_dispatch_work_fn
);
1206 /* activate policy */
1207 ret
= blkcg_activate_policy(q
, &blkcg_policy_throtl
);
1213 void blk_throtl_exit(struct request_queue
*q
)
1216 throtl_shutdown_wq(q
);
1217 blkcg_deactivate_policy(q
, &blkcg_policy_throtl
);
1221 static int __init
throtl_init(void)
1223 kthrotld_workqueue
= alloc_workqueue("kthrotld", WQ_MEM_RECLAIM
, 0);
1224 if (!kthrotld_workqueue
)
1225 panic("Failed to create kthrotld\n");
1227 return blkcg_policy_register(&blkcg_policy_throtl
);
1230 module_init(throtl_init
);