util/throttle.c

   1 /*
   2  * QEMU throttling infrastructure
   3  *
   4  * Copyright (C) Nodalink, EURL. 2013-2014
   5  * Copyright (C) Igalia, S.L. 2015
   6  *
   7  * Authors:
   8  *   Benoît 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  */
  24
  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"
  30
  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)
  37 {
  38     double leak;
  39
  40     /* compute how much to leak */
  41     leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
  42
  43     /* make the bucket leak */
  44     bkt->level = MAX(bkt->level - leak, 0);
  45
  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     }
  53 }
  54
  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)
  60 {
  61     /* compute the time elapsed since the last leak */
  62     int64_t delta_ns = now - ts->previous_leak;
  63     int i;
  64
  65     ts->previous_leak = now;
  66
  67     if (delta_ns <= 0) {
  68         return;
  69     }
  70
  71     /* make each bucket leak */
  72     for (i = 0; i < BUCKETS_COUNT; i++) {
  73         throttle_leak_bucket(&ts->cfg.buckets[i], delta_ns);
  74     }
  75 }
  76
  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)
  84 {
  85     double wait = extra * NANOSECONDS_PER_SECOND;
  86     wait /= limit;
  87     return wait;
  88 }
  89
  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)
  96 {
  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 */
 100
 101     if (!bkt->avg) {
 102         return 0;
 103     }
 104
 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     }
 117
 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     }
 123
 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     }
 133
 134     return 0;
 135 }
 136
 137 /* This function compute the time that must be waited while this IO
 138  *
 139  * @direction:  throttle direction
 140  * @ret:        time to wait
 141  */
 142 static int64_t throttle_compute_wait_for(ThrottleState *ts,
 143                                          ThrottleDirection direction)
 144 {
 145     static const BucketType to_check[THROTTLE_MAX][4] = {
 146                                   {THROTTLE_BPS_TOTAL,
 147                                    THROTTLE_OPS_TOTAL,
 148                                    THROTTLE_BPS_READ,
 149                                    THROTTLE_OPS_READ},
 150                                   {THROTTLE_BPS_TOTAL,
 151                                    THROTTLE_OPS_TOTAL,
 152                                    THROTTLE_BPS_WRITE,
 153                                    THROTTLE_OPS_WRITE}, };
 154     int64_t wait, max_wait = 0;
 155     int i;
 156
 157     for (i = 0; i < ARRAY_SIZE(to_check[THROTTLE_READ]); i++) {
 158         BucketType index = to_check[direction][i];
 159         wait = throttle_compute_wait(&ts->cfg.buckets[index]);
 160         if (wait > max_wait) {
 161             max_wait = wait;
 162         }
 163     }
 164
 165     return max_wait;
 166 }
 167
 168 /* compute the timer for this type of operation
 169  *
 170  * @direction:  throttle direction
 171  * @now:        the current clock timestamp
 172  * @next_timestamp: the resulting timer
 173  * @ret:        true if a timer must be set
 174  */
 175 static bool throttle_compute_timer(ThrottleState *ts,
 176                                    ThrottleDirection direction,
 177                                    int64_t now,
 178                                    int64_t *next_timestamp)
 179 {
 180     int64_t wait;
 181
 182     /* leak proportionally to the time elapsed */
 183     throttle_do_leak(ts, now);
 184
 185     /* compute the wait time if any */
 186     wait = throttle_compute_wait_for(ts, direction);
 187
 188     /* if the code must wait compute when the next timer should fire */
 189     if (wait) {
 190         *next_timestamp = now + wait;
 191         return true;
 192     }
 193
 194     /* else no need to wait at all */
 195     *next_timestamp = now;
 196     return false;
 197 }
 198
 199 /* Add timers to event loop */
 200 void throttle_timers_attach_aio_context(ThrottleTimers *tt,
 201                                         AioContext *new_context)
 202 {
 203     ThrottleDirection dir;
 204
 205     for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
 206         if (tt->timer_cb[dir]) {
 207             tt->timers[dir] =
 208                 aio_timer_new(new_context, tt->clock_type, SCALE_NS,
 209                               tt->timer_cb[dir], tt->timer_opaque);
 210         }
 211     }
 212 }
 213
 214 /*
 215  * Initialize the ThrottleConfig structure to a valid state
 216  * @cfg: the config to initialize
 217  */
 218 void throttle_config_init(ThrottleConfig *cfg)
 219 {
 220     unsigned i;
 221     memset(cfg, 0, sizeof(*cfg));
 222     for (i = 0; i < BUCKETS_COUNT; i++) {
 223         cfg->buckets[i].burst_length = 1;
 224     }
 225 }
 226
 227 /* To be called first on the ThrottleState */
 228 void throttle_init(ThrottleState *ts)
 229 {
 230     memset(ts, 0, sizeof(ThrottleState));
 231     throttle_config_init(&ts->cfg);
 232 }
 233
 234 /* To be called first on the ThrottleTimers */
 235 void throttle_timers_init(ThrottleTimers *tt,
 236                           AioContext *aio_context,
 237                           QEMUClockType clock_type,
 238                           QEMUTimerCB *read_timer_cb,
 239                           QEMUTimerCB *write_timer_cb,
 240                           void *timer_opaque)
 241 {
 242     assert(read_timer_cb || write_timer_cb);
 243     memset(tt, 0, sizeof(ThrottleTimers));
 244
 245     tt->clock_type = clock_type;
 246     tt->timer_cb[THROTTLE_READ] = read_timer_cb;
 247     tt->timer_cb[THROTTLE_WRITE] = write_timer_cb;
 248     tt->timer_opaque = timer_opaque;
 249     throttle_timers_attach_aio_context(tt, aio_context);
 250 }
 251
 252 /* destroy a timer */
 253 static void throttle_timer_destroy(QEMUTimer **timer)
 254 {
 255     if (*timer == NULL) {
 256         return;
 257     }
 258
 259     timer_free(*timer);
 260     *timer = NULL;
 261 }
 262
 263 /* Remove timers from event loop */
 264 void throttle_timers_detach_aio_context(ThrottleTimers *tt)
 265 {
 266     ThrottleDirection dir;
 267
 268     for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
 269         throttle_timer_destroy(&tt->timers[dir]);
 270     }
 271 }
 272
 273 /* To be called last on the ThrottleTimers */
 274 void throttle_timers_destroy(ThrottleTimers *tt)
 275 {
 276     throttle_timers_detach_aio_context(tt);
 277 }
 278
 279 /* is any throttling timer configured */
 280 bool throttle_timers_are_initialized(ThrottleTimers *tt)
 281 {
 282     ThrottleDirection dir;
 283
 284     for (dir = THROTTLE_READ; dir < THROTTLE_MAX; dir++) {
 285         if (tt->timers[dir]) {
 286             return true;
 287         }
 288     }
 289
 290     return false;
 291 }
 292
 293 /* Does any throttling must be done
 294  *
 295  * @cfg: the throttling configuration to inspect
 296  * @ret: true if throttling must be done else false
 297  */
 298 bool throttle_enabled(ThrottleConfig *cfg)
 299 {
 300     int i;
 301
 302     for (i = 0; i < BUCKETS_COUNT; i++) {
 303         if (cfg->buckets[i].avg > 0) {
 304             return true;
 305         }
 306     }
 307
 308     return false;
 309 }
 310
 311 /* check if a throttling configuration is valid
 312  * @cfg: the throttling configuration to inspect
 313  * @ret: true if valid else false
 314  * @errp: error object
 315  */
 316 bool throttle_is_valid(ThrottleConfig *cfg, Error **errp)
 317 {
 318     int i;
 319     bool bps_flag, ops_flag;
 320     bool bps_max_flag, ops_max_flag;
 321
 322     bps_flag = cfg->buckets[THROTTLE_BPS_TOTAL].avg &&
 323                (cfg->buckets[THROTTLE_BPS_READ].avg ||
 324                 cfg->buckets[THROTTLE_BPS_WRITE].avg);
 325
 326     ops_flag = cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
 327                (cfg->buckets[THROTTLE_OPS_READ].avg ||
 328                 cfg->buckets[THROTTLE_OPS_WRITE].avg);
 329
 330     bps_max_flag = cfg->buckets[THROTTLE_BPS_TOTAL].max &&
 331                   (cfg->buckets[THROTTLE_BPS_READ].max  ||
 332                    cfg->buckets[THROTTLE_BPS_WRITE].max);
 333
 334     ops_max_flag = cfg->buckets[THROTTLE_OPS_TOTAL].max &&
 335                    (cfg->buckets[THROTTLE_OPS_READ].max ||
 336                    cfg->buckets[THROTTLE_OPS_WRITE].max);
 337
 338     if (bps_flag || ops_flag || bps_max_flag || ops_max_flag) {
 339         error_setg(errp, "bps/iops/max total values and read/write values"
 340                    " cannot be used at the same time");
 341         return false;
 342     }
 343
 344     if (cfg->op_size &&
 345         !cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
 346         !cfg->buckets[THROTTLE_OPS_READ].avg &&
 347         !cfg->buckets[THROTTLE_OPS_WRITE].avg) {
 348         error_setg(errp, "iops size requires an iops value to be set");
 349         return false;
 350     }
 351
 352     for (i = 0; i < BUCKETS_COUNT; i++) {
 353         LeakyBucket *bkt = &cfg->buckets[i];
 354         if (bkt->avg > THROTTLE_VALUE_MAX || bkt->max > THROTTLE_VALUE_MAX) {
 355             error_setg(errp, "bps/iops/max values must be within [0, %lld]",
 356                        THROTTLE_VALUE_MAX);
 357             return false;
 358         }
 359
 360         if (!bkt->burst_length) {
 361             error_setg(errp, "the burst length cannot be 0");
 362             return false;
 363         }
 364
 365         if (bkt->burst_length > 1 && !bkt->max) {
 366             error_setg(errp, "burst length set without burst rate");
 367             return false;
 368         }
 369
 370         if (bkt->max && bkt->burst_length > THROTTLE_VALUE_MAX / bkt->max) {
 371             error_setg(errp, "burst length too high for this burst rate");
 372             return false;
 373         }
 374
 375         if (bkt->max && !bkt->avg) {
 376             error_setg(errp, "bps_max/iops_max require corresponding"
 377                        " bps/iops values");
 378             return false;
 379         }
 380
 381         if (bkt->max && bkt->max < bkt->avg) {
 382             error_setg(errp, "bps_max/iops_max cannot be lower than bps/iops");
 383             return false;
 384         }
 385     }
 386
 387     return true;
 388 }
 389
 390 /* Used to configure the throttle
 391  *
 392  * @ts: the throttle state we are working on
 393  * @clock_type: the group's clock_type
 394  * @cfg: the config to set
 395  */
 396 void throttle_config(ThrottleState *ts,
 397                      QEMUClockType clock_type,
 398                      ThrottleConfig *cfg)
 399 {
 400     int i;
 401
 402     ts->cfg = *cfg;
 403
 404     /* Zero bucket level */
 405     for (i = 0; i < BUCKETS_COUNT; i++) {
 406         ts->cfg.buckets[i].level = 0;
 407         ts->cfg.buckets[i].burst_level = 0;
 408     }
 409
 410     ts->previous_leak = qemu_clock_get_ns(clock_type);
 411 }
 412
 413 /* used to get config
 414  *
 415  * @ts:  the throttle state we are working on
 416  * @cfg: the config to write
 417  */
 418 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg)
 419 {
 420     *cfg = ts->cfg;
 421 }
 422
 423
 424 /* Schedule the read or write timer if needed
 425  *
 426  * NOTE: this function is not unit tested due to it's usage of timer_mod
 427  *
 428  * @tt:       the timers structure
 429  * @direction: throttle direction
 430  * @ret:      true if the timer has been scheduled else false
 431  */
 432 bool throttle_schedule_timer(ThrottleState *ts,
 433                              ThrottleTimers *tt,
 434                              ThrottleDirection direction)
 435 {
 436     int64_t now = qemu_clock_get_ns(tt->clock_type);
 437     int64_t next_timestamp;
 438     QEMUTimer *timer;
 439     bool must_wait;
 440
 441     assert(direction < THROTTLE_MAX);
 442     timer = tt->timers[direction];
 443     assert(timer);
 444
 445     must_wait = throttle_compute_timer(ts,
 446                                        direction,
 447                                        now,
 448                                        &next_timestamp);
 449
 450     /* request not throttled */
 451     if (!must_wait) {
 452         return false;
 453     }
 454
 455     /* request throttled and timer pending -> do nothing */
 456     if (timer_pending(timer)) {
 457         return true;
 458     }
 459
 460     /* request throttled and timer not pending -> arm timer */
 461     timer_mod(timer, next_timestamp);
 462     return true;
 463 }
 464
 465 /* do the accounting for this operation
 466  *
 467  * @direction: throttle direction
 468  * @size:     the size of the operation
 469  */
 470 void throttle_account(ThrottleState *ts, ThrottleDirection direction,
 471                       uint64_t size)
 472 {
 473     static const BucketType bucket_types_size[THROTTLE_MAX][2] = {
 474         { THROTTLE_BPS_TOTAL, THROTTLE_BPS_READ },
 475         { THROTTLE_BPS_TOTAL, THROTTLE_BPS_WRITE }
 476     };
 477     static const BucketType bucket_types_units[THROTTLE_MAX][2] = {
 478         { THROTTLE_OPS_TOTAL, THROTTLE_OPS_READ },
 479         { THROTTLE_OPS_TOTAL, THROTTLE_OPS_WRITE }
 480     };
 481     double units = 1.0;
 482     unsigned i;
 483
 484     assert(direction < THROTTLE_MAX);
 485     /* if cfg.op_size is defined and smaller than size we compute unit count */
 486     if (ts->cfg.op_size && size > ts->cfg.op_size) {
 487         units = (double) size / ts->cfg.op_size;
 488     }
 489
 490     for (i = 0; i < ARRAY_SIZE(bucket_types_size[THROTTLE_READ]); i++) {
 491         LeakyBucket *bkt;
 492
 493         bkt = &ts->cfg.buckets[bucket_types_size[direction][i]];
 494         bkt->level += size;
 495         if (bkt->burst_length > 1) {
 496             bkt->burst_level += size;
 497         }
 498
 499         bkt = &ts->cfg.buckets[bucket_types_units[direction][i]];
 500         bkt->level += units;
 501         if (bkt->burst_length > 1) {
 502             bkt->burst_level += units;
 503         }
 504     }
 505 }
 506
 507 /* return a ThrottleConfig based on the options in a ThrottleLimits
 508  *
 509  * @arg:    the ThrottleLimits object to read from
 510  * @cfg:    the ThrottleConfig to edit
 511  * @errp:   error object
 512  */
 513 void throttle_limits_to_config(ThrottleLimits *arg, ThrottleConfig *cfg,
 514                                Error **errp)
 515 {
 516     if (arg->has_bps_total) {
 517         cfg->buckets[THROTTLE_BPS_TOTAL].avg = arg->bps_total;
 518     }
 519     if (arg->has_bps_read) {
 520         cfg->buckets[THROTTLE_BPS_READ].avg  = arg->bps_read;
 521     }
 522     if (arg->has_bps_write) {
 523         cfg->buckets[THROTTLE_BPS_WRITE].avg = arg->bps_write;
 524     }
 525
 526     if (arg->has_iops_total) {
 527         cfg->buckets[THROTTLE_OPS_TOTAL].avg = arg->iops_total;
 528     }
 529     if (arg->has_iops_read) {
 530         cfg->buckets[THROTTLE_OPS_READ].avg  = arg->iops_read;
 531     }
 532     if (arg->has_iops_write) {
 533         cfg->buckets[THROTTLE_OPS_WRITE].avg = arg->iops_write;
 534     }
 535
 536     if (arg->has_bps_total_max) {
 537         cfg->buckets[THROTTLE_BPS_TOTAL].max = arg->bps_total_max;
 538     }
 539     if (arg->has_bps_read_max) {
 540         cfg->buckets[THROTTLE_BPS_READ].max = arg->bps_read_max;
 541     }
 542     if (arg->has_bps_write_max) {
 543         cfg->buckets[THROTTLE_BPS_WRITE].max = arg->bps_write_max;
 544     }
 545     if (arg->has_iops_total_max) {
 546         cfg->buckets[THROTTLE_OPS_TOTAL].max = arg->iops_total_max;
 547     }
 548     if (arg->has_iops_read_max) {
 549         cfg->buckets[THROTTLE_OPS_READ].max = arg->iops_read_max;
 550     }
 551     if (arg->has_iops_write_max) {
 552         cfg->buckets[THROTTLE_OPS_WRITE].max = arg->iops_write_max;
 553     }
 554
 555     if (arg->has_bps_total_max_length) {
 556         if (arg->bps_total_max_length > UINT_MAX) {
 557             error_setg(errp, "bps-total-max-length value must be in"
 558                              " the range [0, %u]", UINT_MAX);
 559             return;
 560         }
 561         cfg->buckets[THROTTLE_BPS_TOTAL].burst_length = arg->bps_total_max_length;
 562     }
 563     if (arg->has_bps_read_max_length) {
 564         if (arg->bps_read_max_length > UINT_MAX) {
 565             error_setg(errp, "bps-read-max-length value must be in"
 566                              " the range [0, %u]", UINT_MAX);
 567             return;
 568         }
 569         cfg->buckets[THROTTLE_BPS_READ].burst_length = arg->bps_read_max_length;
 570     }
 571     if (arg->has_bps_write_max_length) {
 572         if (arg->bps_write_max_length > UINT_MAX) {
 573             error_setg(errp, "bps-write-max-length value must be in"
 574                              " the range [0, %u]", UINT_MAX);
 575             return;
 576         }
 577         cfg->buckets[THROTTLE_BPS_WRITE].burst_length = arg->bps_write_max_length;
 578     }
 579     if (arg->has_iops_total_max_length) {
 580         if (arg->iops_total_max_length > UINT_MAX) {
 581             error_setg(errp, "iops-total-max-length value must be in"
 582                              " the range [0, %u]", UINT_MAX);
 583             return;
 584         }
 585         cfg->buckets[THROTTLE_OPS_TOTAL].burst_length = arg->iops_total_max_length;
 586     }
 587     if (arg->has_iops_read_max_length) {
 588         if (arg->iops_read_max_length > UINT_MAX) {
 589             error_setg(errp, "iops-read-max-length value must be in"
 590                              " the range [0, %u]", UINT_MAX);
 591             return;
 592         }
 593         cfg->buckets[THROTTLE_OPS_READ].burst_length = arg->iops_read_max_length;
 594     }
 595     if (arg->has_iops_write_max_length) {
 596         if (arg->iops_write_max_length > UINT_MAX) {
 597             error_setg(errp, "iops-write-max-length value must be in"
 598                              " the range [0, %u]", UINT_MAX);
 599             return;
 600         }
 601         cfg->buckets[THROTTLE_OPS_WRITE].burst_length = arg->iops_write_max_length;
 602     }
 603
 604     if (arg->has_iops_size) {
 605         cfg->op_size = arg->iops_size;
 606     }
 607
 608     throttle_is_valid(cfg, errp);
 609 }
 610
 611 /* write the options of a ThrottleConfig to a ThrottleLimits
 612  *
 613  * @cfg:    the ThrottleConfig to read from
 614  * @var:    the ThrottleLimits to write to
 615  */
 616 void throttle_config_to_limits(ThrottleConfig *cfg, ThrottleLimits *var)
 617 {
 618     var->bps_total               = cfg->buckets[THROTTLE_BPS_TOTAL].avg;
 619     var->bps_read                = cfg->buckets[THROTTLE_BPS_READ].avg;
 620     var->bps_write               = cfg->buckets[THROTTLE_BPS_WRITE].avg;
 621     var->iops_total              = cfg->buckets[THROTTLE_OPS_TOTAL].avg;
 622     var->iops_read               = cfg->buckets[THROTTLE_OPS_READ].avg;
 623     var->iops_write              = cfg->buckets[THROTTLE_OPS_WRITE].avg;
 624     var->bps_total_max           = cfg->buckets[THROTTLE_BPS_TOTAL].max;
 625     var->bps_read_max            = cfg->buckets[THROTTLE_BPS_READ].max;
 626     var->bps_write_max           = cfg->buckets[THROTTLE_BPS_WRITE].max;
 627     var->iops_total_max          = cfg->buckets[THROTTLE_OPS_TOTAL].max;
 628     var->iops_read_max           = cfg->buckets[THROTTLE_OPS_READ].max;
 629     var->iops_write_max          = cfg->buckets[THROTTLE_OPS_WRITE].max;
 630     var->bps_total_max_length    = cfg->buckets[THROTTLE_BPS_TOTAL].burst_length;
 631     var->bps_read_max_length     = cfg->buckets[THROTTLE_BPS_READ].burst_length;
 632     var->bps_write_max_length    = cfg->buckets[THROTTLE_BPS_WRITE].burst_length;
 633     var->iops_total_max_length   = cfg->buckets[THROTTLE_OPS_TOTAL].burst_length;
 634     var->iops_read_max_length    = cfg->buckets[THROTTLE_OPS_READ].burst_length;
 635     var->iops_write_max_length   = cfg->buckets[THROTTLE_OPS_WRITE].burst_length;
 636     var->iops_size               = cfg->op_size;
 637
 638     var->has_bps_total = true;
 639     var->has_bps_read = true;
 640     var->has_bps_write = true;
 641     var->has_iops_total = true;
 642     var->has_iops_read = true;
 643     var->has_iops_write = true;
 644     var->has_bps_total_max = true;
 645     var->has_bps_read_max = true;
 646     var->has_bps_write_max = true;
 647     var->has_iops_total_max = true;
 648     var->has_iops_read_max = true;
 649     var->has_iops_write_max = true;
 650     var->has_bps_read_max_length = true;
 651     var->has_bps_total_max_length = true;
 652     var->has_bps_write_max_length = true;
 653     var->has_iops_total_max_length = true;
 654     var->has_iops_read_max_length = true;
 655     var->has_iops_write_max_length = true;
 656     var->has_iops_size = true;
 657 }