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         extra = bkt->burst_level - burst_bucket_size;
 128         if (extra > 0) {
 129             return throttle_do_compute_wait(bkt->max, extra);
 130         }
 131     }
 132
 133     return 0;
 134 }
 135
 136 /* This function compute the time that must be waited while this IO
 137  *
 138  * @is_write:   true if the current IO is a write, false if it's a read
 139  * @ret:        time to wait
 140  */
 141 static int64_t throttle_compute_wait_for(ThrottleState *ts,
 142                                          bool is_write)
 143 {
 144     BucketType to_check[2][4] = { {THROTTLE_BPS_TOTAL,
 145                                    THROTTLE_OPS_TOTAL,
 146                                    THROTTLE_BPS_READ,
 147                                    THROTTLE_OPS_READ},
 148                                   {THROTTLE_BPS_TOTAL,
 149                                    THROTTLE_OPS_TOTAL,
 150                                    THROTTLE_BPS_WRITE,
 151                                    THROTTLE_OPS_WRITE}, };
 152     int64_t wait, max_wait = 0;
 153     int i;
 154
 155     for (i = 0; i < 4; i++) {
 156         BucketType index = to_check[is_write][i];
 157         wait = throttle_compute_wait(&ts->cfg.buckets[index]);
 158         if (wait > max_wait) {
 159             max_wait = wait;
 160         }
 161     }
 162
 163     return max_wait;
 164 }
 165
 166 /* compute the timer for this type of operation
 167  *
 168  * @is_write:   the type of operation
 169  * @now:        the current clock timestamp
 170  * @next_timestamp: the resulting timer
 171  * @ret:        true if a timer must be set
 172  */
 173 static bool throttle_compute_timer(ThrottleState *ts,
 174                                    bool is_write,
 175                                    int64_t now,
 176                                    int64_t *next_timestamp)
 177 {
 178     int64_t wait;
 179
 180     /* leak proportionally to the time elapsed */
 181     throttle_do_leak(ts, now);
 182
 183     /* compute the wait time if any */
 184     wait = throttle_compute_wait_for(ts, is_write);
 185
 186     /* if the code must wait compute when the next timer should fire */
 187     if (wait) {
 188         *next_timestamp = now + wait;
 189         return true;
 190     }
 191
 192     /* else no need to wait at all */
 193     *next_timestamp = now;
 194     return false;
 195 }
 196
 197 /* Add timers to event loop */
 198 void throttle_timers_attach_aio_context(ThrottleTimers *tt,
 199                                         AioContext *new_context)
 200 {
 201     tt->timers[0] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
 202                                   tt->read_timer_cb, tt->timer_opaque);
 203     tt->timers[1] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
 204                                   tt->write_timer_cb, tt->timer_opaque);
 205 }
 206
 207 /*
 208  * Initialize the ThrottleConfig structure to a valid state
 209  * @cfg: the config to initialize
 210  */
 211 void throttle_config_init(ThrottleConfig *cfg)
 212 {
 213     unsigned i;
 214     memset(cfg, 0, sizeof(*cfg));
 215     for (i = 0; i < BUCKETS_COUNT; i++) {
 216         cfg->buckets[i].burst_length = 1;
 217     }
 218 }
 219
 220 /* To be called first on the ThrottleState */
 221 void throttle_init(ThrottleState *ts)
 222 {
 223     memset(ts, 0, sizeof(ThrottleState));
 224     throttle_config_init(&ts->cfg);
 225 }
 226
 227 /* To be called first on the ThrottleTimers */
 228 void throttle_timers_init(ThrottleTimers *tt,
 229                           AioContext *aio_context,
 230                           QEMUClockType clock_type,
 231                           QEMUTimerCB *read_timer_cb,
 232                           QEMUTimerCB *write_timer_cb,
 233                           void *timer_opaque)
 234 {
 235     memset(tt, 0, sizeof(ThrottleTimers));
 236
 237     tt->clock_type = clock_type;
 238     tt->read_timer_cb = read_timer_cb;
 239     tt->write_timer_cb = write_timer_cb;
 240     tt->timer_opaque = timer_opaque;
 241     throttle_timers_attach_aio_context(tt, aio_context);
 242 }
 243
 244 /* destroy a timer */
 245 static void throttle_timer_destroy(QEMUTimer **timer)
 246 {
 247     assert(*timer != NULL);
 248
 249     timer_del(*timer);
 250     timer_free(*timer);
 251     *timer = NULL;
 252 }
 253
 254 /* Remove timers from event loop */
 255 void throttle_timers_detach_aio_context(ThrottleTimers *tt)
 256 {
 257     int i;
 258
 259     for (i = 0; i < 2; i++) {
 260         throttle_timer_destroy(&tt->timers[i]);
 261     }
 262 }
 263
 264 /* To be called last on the ThrottleTimers */
 265 void throttle_timers_destroy(ThrottleTimers *tt)
 266 {
 267     throttle_timers_detach_aio_context(tt);
 268 }
 269
 270 /* is any throttling timer configured */
 271 bool throttle_timers_are_initialized(ThrottleTimers *tt)
 272 {
 273     if (tt->timers[0]) {
 274         return true;
 275     }
 276
 277     return false;
 278 }
 279
 280 /* Does any throttling must be done
 281  *
 282  * @cfg: the throttling configuration to inspect
 283  * @ret: true if throttling must be done else false
 284  */
 285 bool throttle_enabled(ThrottleConfig *cfg)
 286 {
 287     int i;
 288
 289     for (i = 0; i < BUCKETS_COUNT; i++) {
 290         if (cfg->buckets[i].avg > 0) {
 291             return true;
 292         }
 293     }
 294
 295     return false;
 296 }
 297
 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)
 304 {
 305     int i;
 306     bool bps_flag, ops_flag;
 307     bool bps_max_flag, ops_max_flag;
 308
 309     bps_flag = cfg->buckets[THROTTLE_BPS_TOTAL].avg &&
 310                (cfg->buckets[THROTTLE_BPS_READ].avg ||
 311                 cfg->buckets[THROTTLE_BPS_WRITE].avg);
 312
 313     ops_flag = cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
 314                (cfg->buckets[THROTTLE_OPS_READ].avg ||
 315                 cfg->buckets[THROTTLE_OPS_WRITE].avg);
 316
 317     bps_max_flag = cfg->buckets[THROTTLE_BPS_TOTAL].max &&
 318                   (cfg->buckets[THROTTLE_BPS_READ].max  ||
 319                    cfg->buckets[THROTTLE_BPS_WRITE].max);
 320
 321     ops_max_flag = cfg->buckets[THROTTLE_OPS_TOTAL].max &&
 322                    (cfg->buckets[THROTTLE_OPS_READ].max ||
 323                    cfg->buckets[THROTTLE_OPS_WRITE].max);
 324
 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     }
 330
 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     }
 338
 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         }
 346
 347         if (!bkt->burst_length) {
 348             error_setg(errp, "the burst length cannot be 0");
 349             return false;
 350         }
 351
 352         if (bkt->burst_length > 1 && !bkt->max) {
 353             error_setg(errp, "burst length set without burst rate");
 354             return false;
 355         }
 356
 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         }
 361
 362         if (bkt->max && !bkt->avg) {
 363             error_setg(errp, "bps_max/iops_max require corresponding"
 364                        " bps/iops values");
 365             return false;
 366         }
 367
 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     }
 373
 374     return true;
 375 }
 376
 377 /* Used to configure the throttle
 378  *
 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)
 386 {
 387     int i;
 388
 389     ts->cfg = *cfg;
 390
 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     }
 396
 397     ts->previous_leak = qemu_clock_get_ns(clock_type);
 398 }
 399
 400 /* used to get config
 401  *
 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)
 406 {
 407     *cfg = ts->cfg;
 408 }
 409
 410
 411 /* Schedule the read or write timer if needed
 412  *
 413  * NOTE: this function is not unit tested due to it's usage of timer_mod
 414  *
 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)
 422 {
 423     int64_t now = qemu_clock_get_ns(tt->clock_type);
 424     int64_t next_timestamp;
 425     bool must_wait;
 426
 427     must_wait = throttle_compute_timer(ts,
 428                                        is_write,
 429                                        now,
 430                                        &next_timestamp);
 431
 432     /* request not throttled */
 433     if (!must_wait) {
 434         return false;
 435     }
 436
 437     /* request throttled and timer pending -> do nothing */
 438     if (timer_pending(tt->timers[is_write])) {
 439         return true;
 440     }
 441
 442     /* request throttled and timer not pending -> arm timer */
 443     timer_mod(tt->timers[is_write], next_timestamp);
 444     return true;
 445 }
 446
 447 /* do the accounting for this operation
 448  *
 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)
 453 {
 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;
 464
 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     }
 469
 470     for (i = 0; i < 2; i++) {
 471         LeakyBucket *bkt;
 472
 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         }
 478
 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     }
 485 }
 486
 487 /* return a ThrottleConfig based on the options in a ThrottleLimits
 488  *
 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)
 495 {
 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     }
 505
 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     }
 515
 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     }
 534
 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     }
 583
 584     if (arg->has_iops_size) {
 585         cfg->op_size = arg->iops_size;
 586     }
 587
 588     throttle_is_valid(cfg, errp);
 589 }
 590
 591 /* write the options of a ThrottleConfig to a ThrottleLimits
 592  *
 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)
 597 {
 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;
 617
 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;
 637 }