Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
[qemu/ar7.git] / util / throttle.c
blob81f247a8d18fccffc6c05ec36940fc04a617215b
1 /*
2 * QEMU throttling infrastructure
4 * Copyright (C) Nodalink, EURL. 2013-2014
5 * Copyright (C) Igalia, S.L. 2015
7 * Authors:
8 * BenoƮt Canet <benoit.canet@nodalink.com>
9 * Alberto Garcia <berto@igalia.com>
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 or
14 * (at your option) version 3 of the License.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, see <http://www.gnu.org/licenses/>.
25 #include "qemu/osdep.h"
26 #include "qapi/error.h"
27 #include "qemu/throttle.h"
28 #include "qemu/timer.h"
29 #include "block/aio.h"
31 /* This function make a bucket leak
33 * @bkt: the bucket to make leak
34 * @delta_ns: the time delta
36 void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta_ns)
38 double leak;
40 /* compute how much to leak */
41 leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
43 /* make the bucket leak */
44 bkt->level = MAX(bkt->level - leak, 0);
46 /* if we allow bursts for more than one second we also need to
47 * keep track of bkt->burst_level so the bkt->max goal per second
48 * is attained */
49 if (bkt->burst_length > 1) {
50 leak = (bkt->max * (double) delta_ns) / NANOSECONDS_PER_SECOND;
51 bkt->burst_level = MAX(bkt->burst_level - leak, 0);
55 /* Calculate the time delta since last leak and make proportionals leaks
57 * @now: the current timestamp in ns
59 static void throttle_do_leak(ThrottleState *ts, int64_t now)
61 /* compute the time elapsed since the last leak */
62 int64_t delta_ns = now - ts->previous_leak;
63 int i;
65 ts->previous_leak = now;
67 if (delta_ns <= 0) {
68 return;
71 /* make each bucket leak */
72 for (i = 0; i < BUCKETS_COUNT; i++) {
73 throttle_leak_bucket(&ts->cfg.buckets[i], delta_ns);
77 /* do the real job of computing the time to wait
79 * @limit: the throttling limit
80 * @extra: the number of operation to delay
81 * @ret: the time to wait in ns
83 static int64_t throttle_do_compute_wait(double limit, double extra)
85 double wait = extra * NANOSECONDS_PER_SECOND;
86 wait /= limit;
87 return wait;
90 /* This function compute the wait time in ns that a leaky bucket should trigger
92 * @bkt: the leaky bucket we operate on
93 * @ret: the resulting wait time in ns or 0 if the operation can go through
95 int64_t throttle_compute_wait(LeakyBucket *bkt)
97 double extra; /* the number of extra units blocking the io */
98 double bucket_size; /* I/O before throttling to bkt->avg */
99 double burst_bucket_size; /* Before throttling to bkt->max */
101 if (!bkt->avg) {
102 return 0;
105 if (!bkt->max) {
106 /* If bkt->max is 0 we still want to allow short bursts of I/O
107 * from the guest, otherwise every other request will be throttled
108 * and performance will suffer considerably. */
109 bucket_size = (double) bkt->avg / 10;
110 burst_bucket_size = 0;
111 } else {
112 /* If we have a burst limit then we have to wait until all I/O
113 * at burst rate has finished before throttling to bkt->avg */
114 bucket_size = bkt->max * bkt->burst_length;
115 burst_bucket_size = (double) bkt->max / 10;
118 /* If the main bucket is full then we have to wait */
119 extra = bkt->level - bucket_size;
120 if (extra > 0) {
121 return throttle_do_compute_wait(bkt->avg, extra);
124 /* If the main bucket is not full yet we still have to check the
125 * burst bucket in order to enforce the burst limit */
126 if (bkt->burst_length > 1) {
127 assert(bkt->max > 0); /* see throttle_is_valid() */
128 extra = bkt->burst_level - burst_bucket_size;
129 if (extra > 0) {
130 return throttle_do_compute_wait(bkt->max, extra);
134 return 0;
137 /* This function compute the time that must be waited while this IO
139 * @is_write: true if the current IO is a write, false if it's a read
140 * @ret: time to wait
142 static int64_t throttle_compute_wait_for(ThrottleState *ts,
143 bool is_write)
145 BucketType to_check[2][4] = { {THROTTLE_BPS_TOTAL,
146 THROTTLE_OPS_TOTAL,
147 THROTTLE_BPS_READ,
148 THROTTLE_OPS_READ},
149 {THROTTLE_BPS_TOTAL,
150 THROTTLE_OPS_TOTAL,
151 THROTTLE_BPS_WRITE,
152 THROTTLE_OPS_WRITE}, };
153 int64_t wait, max_wait = 0;
154 int i;
156 for (i = 0; i < 4; i++) {
157 BucketType index = to_check[is_write][i];
158 wait = throttle_compute_wait(&ts->cfg.buckets[index]);
159 if (wait > max_wait) {
160 max_wait = wait;
164 return max_wait;
167 /* compute the timer for this type of operation
169 * @is_write: the type of operation
170 * @now: the current clock timestamp
171 * @next_timestamp: the resulting timer
172 * @ret: true if a timer must be set
174 static bool throttle_compute_timer(ThrottleState *ts,
175 bool is_write,
176 int64_t now,
177 int64_t *next_timestamp)
179 int64_t wait;
181 /* leak proportionally to the time elapsed */
182 throttle_do_leak(ts, now);
184 /* compute the wait time if any */
185 wait = throttle_compute_wait_for(ts, is_write);
187 /* if the code must wait compute when the next timer should fire */
188 if (wait) {
189 *next_timestamp = now + wait;
190 return true;
193 /* else no need to wait at all */
194 *next_timestamp = now;
195 return false;
198 /* Add timers to event loop */
199 void throttle_timers_attach_aio_context(ThrottleTimers *tt,
200 AioContext *new_context)
202 tt->timers[0] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
203 tt->read_timer_cb, tt->timer_opaque);
204 tt->timers[1] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
205 tt->write_timer_cb, tt->timer_opaque);
209 * Initialize the ThrottleConfig structure to a valid state
210 * @cfg: the config to initialize
212 void throttle_config_init(ThrottleConfig *cfg)
214 unsigned i;
215 memset(cfg, 0, sizeof(*cfg));
216 for (i = 0; i < BUCKETS_COUNT; i++) {
217 cfg->buckets[i].burst_length = 1;
221 /* To be called first on the ThrottleState */
222 void throttle_init(ThrottleState *ts)
224 memset(ts, 0, sizeof(ThrottleState));
225 throttle_config_init(&ts->cfg);
228 /* To be called first on the ThrottleTimers */
229 void throttle_timers_init(ThrottleTimers *tt,
230 AioContext *aio_context,
231 QEMUClockType clock_type,
232 QEMUTimerCB *read_timer_cb,
233 QEMUTimerCB *write_timer_cb,
234 void *timer_opaque)
236 memset(tt, 0, sizeof(ThrottleTimers));
238 tt->clock_type = clock_type;
239 tt->read_timer_cb = read_timer_cb;
240 tt->write_timer_cb = write_timer_cb;
241 tt->timer_opaque = timer_opaque;
242 throttle_timers_attach_aio_context(tt, aio_context);
245 /* destroy a timer */
246 static void throttle_timer_destroy(QEMUTimer **timer)
248 assert(*timer != NULL);
250 timer_free(*timer);
251 *timer = NULL;
254 /* Remove timers from event loop */
255 void throttle_timers_detach_aio_context(ThrottleTimers *tt)
257 int i;
259 for (i = 0; i < 2; i++) {
260 throttle_timer_destroy(&tt->timers[i]);
264 /* To be called last on the ThrottleTimers */
265 void throttle_timers_destroy(ThrottleTimers *tt)
267 throttle_timers_detach_aio_context(tt);
270 /* is any throttling timer configured */
271 bool throttle_timers_are_initialized(ThrottleTimers *tt)
273 if (tt->timers[0]) {
274 return true;
277 return false;
280 /* Does any throttling must be done
282 * @cfg: the throttling configuration to inspect
283 * @ret: true if throttling must be done else false
285 bool throttle_enabled(ThrottleConfig *cfg)
287 int i;
289 for (i = 0; i < BUCKETS_COUNT; i++) {
290 if (cfg->buckets[i].avg > 0) {
291 return true;
295 return false;
298 /* check if a throttling configuration is valid
299 * @cfg: the throttling configuration to inspect
300 * @ret: true if valid else false
301 * @errp: error object
303 bool throttle_is_valid(ThrottleConfig *cfg, Error **errp)
305 int i;
306 bool bps_flag, ops_flag;
307 bool bps_max_flag, ops_max_flag;
309 bps_flag = cfg->buckets[THROTTLE_BPS_TOTAL].avg &&
310 (cfg->buckets[THROTTLE_BPS_READ].avg ||
311 cfg->buckets[THROTTLE_BPS_WRITE].avg);
313 ops_flag = cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
314 (cfg->buckets[THROTTLE_OPS_READ].avg ||
315 cfg->buckets[THROTTLE_OPS_WRITE].avg);
317 bps_max_flag = cfg->buckets[THROTTLE_BPS_TOTAL].max &&
318 (cfg->buckets[THROTTLE_BPS_READ].max ||
319 cfg->buckets[THROTTLE_BPS_WRITE].max);
321 ops_max_flag = cfg->buckets[THROTTLE_OPS_TOTAL].max &&
322 (cfg->buckets[THROTTLE_OPS_READ].max ||
323 cfg->buckets[THROTTLE_OPS_WRITE].max);
325 if (bps_flag || ops_flag || bps_max_flag || ops_max_flag) {
326 error_setg(errp, "bps/iops/max total values and read/write values"
327 " cannot be used at the same time");
328 return false;
331 if (cfg->op_size &&
332 !cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
333 !cfg->buckets[THROTTLE_OPS_READ].avg &&
334 !cfg->buckets[THROTTLE_OPS_WRITE].avg) {
335 error_setg(errp, "iops size requires an iops value to be set");
336 return false;
339 for (i = 0; i < BUCKETS_COUNT; i++) {
340 LeakyBucket *bkt = &cfg->buckets[i];
341 if (bkt->avg > THROTTLE_VALUE_MAX || bkt->max > THROTTLE_VALUE_MAX) {
342 error_setg(errp, "bps/iops/max values must be within [0, %lld]",
343 THROTTLE_VALUE_MAX);
344 return false;
347 if (!bkt->burst_length) {
348 error_setg(errp, "the burst length cannot be 0");
349 return false;
352 if (bkt->burst_length > 1 && !bkt->max) {
353 error_setg(errp, "burst length set without burst rate");
354 return false;
357 if (bkt->max && bkt->burst_length > THROTTLE_VALUE_MAX / bkt->max) {
358 error_setg(errp, "burst length too high for this burst rate");
359 return false;
362 if (bkt->max && !bkt->avg) {
363 error_setg(errp, "bps_max/iops_max require corresponding"
364 " bps/iops values");
365 return false;
368 if (bkt->max && bkt->max < bkt->avg) {
369 error_setg(errp, "bps_max/iops_max cannot be lower than bps/iops");
370 return false;
374 return true;
377 /* Used to configure the throttle
379 * @ts: the throttle state we are working on
380 * @clock_type: the group's clock_type
381 * @cfg: the config to set
383 void throttle_config(ThrottleState *ts,
384 QEMUClockType clock_type,
385 ThrottleConfig *cfg)
387 int i;
389 ts->cfg = *cfg;
391 /* Zero bucket level */
392 for (i = 0; i < BUCKETS_COUNT; i++) {
393 ts->cfg.buckets[i].level = 0;
394 ts->cfg.buckets[i].burst_level = 0;
397 ts->previous_leak = qemu_clock_get_ns(clock_type);
400 /* used to get config
402 * @ts: the throttle state we are working on
403 * @cfg: the config to write
405 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg)
407 *cfg = ts->cfg;
411 /* Schedule the read or write timer if needed
413 * NOTE: this function is not unit tested due to it's usage of timer_mod
415 * @tt: the timers structure
416 * @is_write: the type of operation (read/write)
417 * @ret: true if the timer has been scheduled else false
419 bool throttle_schedule_timer(ThrottleState *ts,
420 ThrottleTimers *tt,
421 bool is_write)
423 int64_t now = qemu_clock_get_ns(tt->clock_type);
424 int64_t next_timestamp;
425 bool must_wait;
427 must_wait = throttle_compute_timer(ts,
428 is_write,
429 now,
430 &next_timestamp);
432 /* request not throttled */
433 if (!must_wait) {
434 return false;
437 /* request throttled and timer pending -> do nothing */
438 if (timer_pending(tt->timers[is_write])) {
439 return true;
442 /* request throttled and timer not pending -> arm timer */
443 timer_mod(tt->timers[is_write], next_timestamp);
444 return true;
447 /* do the accounting for this operation
449 * @is_write: the type of operation (read/write)
450 * @size: the size of the operation
452 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size)
454 const BucketType bucket_types_size[2][2] = {
455 { THROTTLE_BPS_TOTAL, THROTTLE_BPS_READ },
456 { THROTTLE_BPS_TOTAL, THROTTLE_BPS_WRITE }
458 const BucketType bucket_types_units[2][2] = {
459 { THROTTLE_OPS_TOTAL, THROTTLE_OPS_READ },
460 { THROTTLE_OPS_TOTAL, THROTTLE_OPS_WRITE }
462 double units = 1.0;
463 unsigned i;
465 /* if cfg.op_size is defined and smaller than size we compute unit count */
466 if (ts->cfg.op_size && size > ts->cfg.op_size) {
467 units = (double) size / ts->cfg.op_size;
470 for (i = 0; i < 2; i++) {
471 LeakyBucket *bkt;
473 bkt = &ts->cfg.buckets[bucket_types_size[is_write][i]];
474 bkt->level += size;
475 if (bkt->burst_length > 1) {
476 bkt->burst_level += size;
479 bkt = &ts->cfg.buckets[bucket_types_units[is_write][i]];
480 bkt->level += units;
481 if (bkt->burst_length > 1) {
482 bkt->burst_level += units;
487 /* return a ThrottleConfig based on the options in a ThrottleLimits
489 * @arg: the ThrottleLimits object to read from
490 * @cfg: the ThrottleConfig to edit
491 * @errp: error object
493 void throttle_limits_to_config(ThrottleLimits *arg, ThrottleConfig *cfg,
494 Error **errp)
496 if (arg->has_bps_total) {
497 cfg->buckets[THROTTLE_BPS_TOTAL].avg = arg->bps_total;
499 if (arg->has_bps_read) {
500 cfg->buckets[THROTTLE_BPS_READ].avg = arg->bps_read;
502 if (arg->has_bps_write) {
503 cfg->buckets[THROTTLE_BPS_WRITE].avg = arg->bps_write;
506 if (arg->has_iops_total) {
507 cfg->buckets[THROTTLE_OPS_TOTAL].avg = arg->iops_total;
509 if (arg->has_iops_read) {
510 cfg->buckets[THROTTLE_OPS_READ].avg = arg->iops_read;
512 if (arg->has_iops_write) {
513 cfg->buckets[THROTTLE_OPS_WRITE].avg = arg->iops_write;
516 if (arg->has_bps_total_max) {
517 cfg->buckets[THROTTLE_BPS_TOTAL].max = arg->bps_total_max;
519 if (arg->has_bps_read_max) {
520 cfg->buckets[THROTTLE_BPS_READ].max = arg->bps_read_max;
522 if (arg->has_bps_write_max) {
523 cfg->buckets[THROTTLE_BPS_WRITE].max = arg->bps_write_max;
525 if (arg->has_iops_total_max) {
526 cfg->buckets[THROTTLE_OPS_TOTAL].max = arg->iops_total_max;
528 if (arg->has_iops_read_max) {
529 cfg->buckets[THROTTLE_OPS_READ].max = arg->iops_read_max;
531 if (arg->has_iops_write_max) {
532 cfg->buckets[THROTTLE_OPS_WRITE].max = arg->iops_write_max;
535 if (arg->has_bps_total_max_length) {
536 if (arg->bps_total_max_length > UINT_MAX) {
537 error_setg(errp, "bps-total-max-length value must be in"
538 " the range [0, %u]", UINT_MAX);
539 return;
541 cfg->buckets[THROTTLE_BPS_TOTAL].burst_length = arg->bps_total_max_length;
543 if (arg->has_bps_read_max_length) {
544 if (arg->bps_read_max_length > UINT_MAX) {
545 error_setg(errp, "bps-read-max-length value must be in"
546 " the range [0, %u]", UINT_MAX);
547 return;
549 cfg->buckets[THROTTLE_BPS_READ].burst_length = arg->bps_read_max_length;
551 if (arg->has_bps_write_max_length) {
552 if (arg->bps_write_max_length > UINT_MAX) {
553 error_setg(errp, "bps-write-max-length value must be in"
554 " the range [0, %u]", UINT_MAX);
555 return;
557 cfg->buckets[THROTTLE_BPS_WRITE].burst_length = arg->bps_write_max_length;
559 if (arg->has_iops_total_max_length) {
560 if (arg->iops_total_max_length > UINT_MAX) {
561 error_setg(errp, "iops-total-max-length value must be in"
562 " the range [0, %u]", UINT_MAX);
563 return;
565 cfg->buckets[THROTTLE_OPS_TOTAL].burst_length = arg->iops_total_max_length;
567 if (arg->has_iops_read_max_length) {
568 if (arg->iops_read_max_length > UINT_MAX) {
569 error_setg(errp, "iops-read-max-length value must be in"
570 " the range [0, %u]", UINT_MAX);
571 return;
573 cfg->buckets[THROTTLE_OPS_READ].burst_length = arg->iops_read_max_length;
575 if (arg->has_iops_write_max_length) {
576 if (arg->iops_write_max_length > UINT_MAX) {
577 error_setg(errp, "iops-write-max-length value must be in"
578 " the range [0, %u]", UINT_MAX);
579 return;
581 cfg->buckets[THROTTLE_OPS_WRITE].burst_length = arg->iops_write_max_length;
584 if (arg->has_iops_size) {
585 cfg->op_size = arg->iops_size;
588 throttle_is_valid(cfg, errp);
591 /* write the options of a ThrottleConfig to a ThrottleLimits
593 * @cfg: the ThrottleConfig to read from
594 * @var: the ThrottleLimits to write to
596 void throttle_config_to_limits(ThrottleConfig *cfg, ThrottleLimits *var)
598 var->bps_total = cfg->buckets[THROTTLE_BPS_TOTAL].avg;
599 var->bps_read = cfg->buckets[THROTTLE_BPS_READ].avg;
600 var->bps_write = cfg->buckets[THROTTLE_BPS_WRITE].avg;
601 var->iops_total = cfg->buckets[THROTTLE_OPS_TOTAL].avg;
602 var->iops_read = cfg->buckets[THROTTLE_OPS_READ].avg;
603 var->iops_write = cfg->buckets[THROTTLE_OPS_WRITE].avg;
604 var->bps_total_max = cfg->buckets[THROTTLE_BPS_TOTAL].max;
605 var->bps_read_max = cfg->buckets[THROTTLE_BPS_READ].max;
606 var->bps_write_max = cfg->buckets[THROTTLE_BPS_WRITE].max;
607 var->iops_total_max = cfg->buckets[THROTTLE_OPS_TOTAL].max;
608 var->iops_read_max = cfg->buckets[THROTTLE_OPS_READ].max;
609 var->iops_write_max = cfg->buckets[THROTTLE_OPS_WRITE].max;
610 var->bps_total_max_length = cfg->buckets[THROTTLE_BPS_TOTAL].burst_length;
611 var->bps_read_max_length = cfg->buckets[THROTTLE_BPS_READ].burst_length;
612 var->bps_write_max_length = cfg->buckets[THROTTLE_BPS_WRITE].burst_length;
613 var->iops_total_max_length = cfg->buckets[THROTTLE_OPS_TOTAL].burst_length;
614 var->iops_read_max_length = cfg->buckets[THROTTLE_OPS_READ].burst_length;
615 var->iops_write_max_length = cfg->buckets[THROTTLE_OPS_WRITE].burst_length;
616 var->iops_size = cfg->op_size;
618 var->has_bps_total = true;
619 var->has_bps_read = true;
620 var->has_bps_write = true;
621 var->has_iops_total = true;
622 var->has_iops_read = true;
623 var->has_iops_write = true;
624 var->has_bps_total_max = true;
625 var->has_bps_read_max = true;
626 var->has_bps_write_max = true;
627 var->has_iops_total_max = true;
628 var->has_iops_read_max = true;
629 var->has_iops_write_max = true;
630 var->has_bps_read_max_length = true;
631 var->has_bps_total_max_length = true;
632 var->has_bps_write_max_length = true;
633 var->has_iops_total_max_length = true;
634 var->has_iops_read_max_length = true;
635 var->has_iops_write_max_length = true;
636 var->has_iops_size = true;