Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210315...
[qemu/ar7.git] / util / throttle.c
blob81f247a8d18fccffc6c05ec36940fc04a617215b
1 /*
2  * QEMU throttling infrastructure
3  *
4  * Copyright (C) Nodalink, EURL. 2013-2014
5  * Copyright (C) Igalia, S.L. 2015
6  *
7  * Authors:
8  *   BenoĆ®t Canet <benoit.canet@nodalink.com>
9  *   Alberto Garcia <berto@igalia.com>
10  *
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.
15  *
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.
20  *
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/>.
23  */
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
32  *
33  * @bkt:   the bucket to make leak
34  * @delta_ns: the time delta
35  */
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);
52     }
55 /* Calculate the time delta since last leak and make proportionals leaks
56  *
57  * @now:      the current timestamp in ns
58  */
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;
69     }
71     /* make each bucket leak */
72     for (i = 0; i < BUCKETS_COUNT; i++) {
73         throttle_leak_bucket(&ts->cfg.buckets[i], delta_ns);
74     }
77 /* do the real job of computing the time to wait
78  *
79  * @limit: the throttling limit
80  * @extra: the number of operation to delay
81  * @ret:   the time to wait in ns
82  */
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
91  *
92  * @bkt: the leaky bucket we operate on
93  * @ret: the resulting wait time in ns or 0 if the operation can go through
94  */
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;
103     }
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;
116     }
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);
122     }
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);
131         }
132     }
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
141  */
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;
161         }
162     }
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
173  */
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;
191     }
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
211  */
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;
218     }
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]);
261     }
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;
275     }
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
284  */
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;
292         }
293     }
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
302  */
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;
329     }
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;
337     }
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;
345         }
347         if (!bkt->burst_length) {
348             error_setg(errp, "the burst length cannot be 0");
349             return false;
350         }
352         if (bkt->burst_length > 1 && !bkt->max) {
353             error_setg(errp, "burst length set without burst rate");
354             return false;
355         }
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;
360         }
362         if (bkt->max && !bkt->avg) {
363             error_setg(errp, "bps_max/iops_max require corresponding"
364                        " bps/iops values");
365             return false;
366         }
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;
371         }
372     }
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
382  */
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;
395     }
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
404  */
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
418  */
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;
435     }
437     /* request throttled and timer pending -> do nothing */
438     if (timer_pending(tt->timers[is_write])) {
439         return true;
440     }
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
451  */
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 }
457     };
458     const BucketType bucket_types_units[2][2] = {
459         { THROTTLE_OPS_TOTAL, THROTTLE_OPS_READ },
460         { THROTTLE_OPS_TOTAL, THROTTLE_OPS_WRITE }
461     };
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;
468     }
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;
477         }
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;
483         }
484     }
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
492  */
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;
498     }
499     if (arg->has_bps_read) {
500         cfg->buckets[THROTTLE_BPS_READ].avg  = arg->bps_read;
501     }
502     if (arg->has_bps_write) {
503         cfg->buckets[THROTTLE_BPS_WRITE].avg = arg->bps_write;
504     }
506     if (arg->has_iops_total) {
507         cfg->buckets[THROTTLE_OPS_TOTAL].avg = arg->iops_total;
508     }
509     if (arg->has_iops_read) {
510         cfg->buckets[THROTTLE_OPS_READ].avg  = arg->iops_read;
511     }
512     if (arg->has_iops_write) {
513         cfg->buckets[THROTTLE_OPS_WRITE].avg = arg->iops_write;
514     }
516     if (arg->has_bps_total_max) {
517         cfg->buckets[THROTTLE_BPS_TOTAL].max = arg->bps_total_max;
518     }
519     if (arg->has_bps_read_max) {
520         cfg->buckets[THROTTLE_BPS_READ].max = arg->bps_read_max;
521     }
522     if (arg->has_bps_write_max) {
523         cfg->buckets[THROTTLE_BPS_WRITE].max = arg->bps_write_max;
524     }
525     if (arg->has_iops_total_max) {
526         cfg->buckets[THROTTLE_OPS_TOTAL].max = arg->iops_total_max;
527     }
528     if (arg->has_iops_read_max) {
529         cfg->buckets[THROTTLE_OPS_READ].max = arg->iops_read_max;
530     }
531     if (arg->has_iops_write_max) {
532         cfg->buckets[THROTTLE_OPS_WRITE].max = arg->iops_write_max;
533     }
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;
540         }
541         cfg->buckets[THROTTLE_BPS_TOTAL].burst_length = arg->bps_total_max_length;
542     }
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;
548         }
549         cfg->buckets[THROTTLE_BPS_READ].burst_length = arg->bps_read_max_length;
550     }
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;
556         }
557         cfg->buckets[THROTTLE_BPS_WRITE].burst_length = arg->bps_write_max_length;
558     }
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;
564         }
565         cfg->buckets[THROTTLE_OPS_TOTAL].burst_length = arg->iops_total_max_length;
566     }
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;
572         }
573         cfg->buckets[THROTTLE_OPS_READ].burst_length = arg->iops_read_max_length;
574     }
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;
580         }
581         cfg->buckets[THROTTLE_OPS_WRITE].burst_length = arg->iops_write_max_length;
582     }
584     if (arg->has_iops_size) {
585         cfg->op_size = arg->iops_size;
586     }
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
595  */
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;