system/dirtylimit.c

   1 /*
   2  * Dirty page rate limit implementation code
   3  *
   4  * Copyright (c) 2022 CHINA TELECOM CO.,LTD.
   5  *
   6  * Authors:
   7  *  Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "qemu/main-loop.h"
  15 #include "qapi/qapi-commands-migration.h"
  16 #include "qapi/qmp/qdict.h"
  17 #include "qapi/error.h"
  18 #include "sysemu/dirtyrate.h"
  19 #include "sysemu/dirtylimit.h"
  20 #include "monitor/hmp.h"
  21 #include "monitor/monitor.h"
  22 #include "exec/memory.h"
  23 #include "exec/target_page.h"
  24 #include "hw/boards.h"
  25 #include "sysemu/kvm.h"
  26 #include "trace.h"
  27 #include "migration/misc.h"
  28 #include "migration/migration.h"
  29 #include "migration/options.h"
  30
  31 /*
  32  * Dirtylimit stop working if dirty page rate error
  33  * value less than DIRTYLIMIT_TOLERANCE_RANGE
  34  */
  35 #define DIRTYLIMIT_TOLERANCE_RANGE  25  /* MB/s */
  36 /*
  37  * Plus or minus vcpu sleep time linearly if dirty
  38  * page rate error value percentage over
  39  * DIRTYLIMIT_LINEAR_ADJUSTMENT_PCT.
  40  * Otherwise, plus or minus a fixed vcpu sleep time.
  41  */
  42 #define DIRTYLIMIT_LINEAR_ADJUSTMENT_PCT     50
  43 /*
  44  * Max vcpu sleep time percentage during a cycle
  45  * composed of dirty ring full and sleep time.
  46  */
  47 #define DIRTYLIMIT_THROTTLE_PCT_MAX 99
  48
  49 struct {
  50     VcpuStat stat;
  51     bool running;
  52     QemuThread thread;
  53 } *vcpu_dirty_rate_stat;
  54
  55 typedef struct VcpuDirtyLimitState {
  56     int cpu_index;
  57     bool enabled;
  58     /*
  59      * Quota dirty page rate, unit is MB/s
  60      * zero if not enabled.
  61      */
  62     uint64_t quota;
  63 } VcpuDirtyLimitState;
  64
  65 struct {
  66     VcpuDirtyLimitState *states;
  67     /* Max cpus number configured by user */
  68     int max_cpus;
  69     /* Number of vcpu under dirtylimit */
  70     int limited_nvcpu;
  71 } *dirtylimit_state;
  72
  73 /* protect dirtylimit_state */
  74 static QemuMutex dirtylimit_mutex;
  75
  76 /* dirtylimit thread quit if dirtylimit_quit is true */
  77 static bool dirtylimit_quit;
  78
  79 static void vcpu_dirty_rate_stat_collect(void)
  80 {
  81     MigrationState *s = migrate_get_current();
  82     VcpuStat stat;
  83     int i = 0;
  84     int64_t period = DIRTYLIMIT_CALC_TIME_MS;
  85
  86     if (migrate_dirty_limit() &&
  87         migration_is_active(s)) {
  88         period = s->parameters.x_vcpu_dirty_limit_period;
  89     }
  90
  91     /* calculate vcpu dirtyrate */
  92     vcpu_calculate_dirtyrate(period,
  93                               &stat,
  94                               GLOBAL_DIRTY_LIMIT,
  95                               false);
  96
  97     for (i = 0; i < stat.nvcpu; i++) {
  98         vcpu_dirty_rate_stat->stat.rates[i].id = i;
  99         vcpu_dirty_rate_stat->stat.rates[i].dirty_rate =
 100             stat.rates[i].dirty_rate;
 101     }
 102
 103     g_free(stat.rates);
 104 }
 105
 106 static void *vcpu_dirty_rate_stat_thread(void *opaque)
 107 {
 108     rcu_register_thread();
 109
 110     /* start log sync */
 111     global_dirty_log_change(GLOBAL_DIRTY_LIMIT, true);
 112
 113     while (qatomic_read(&vcpu_dirty_rate_stat->running)) {
 114         vcpu_dirty_rate_stat_collect();
 115         if (dirtylimit_in_service()) {
 116             dirtylimit_process();
 117         }
 118     }
 119
 120     /* stop log sync */
 121     global_dirty_log_change(GLOBAL_DIRTY_LIMIT, false);
 122
 123     rcu_unregister_thread();
 124     return NULL;
 125 }
 126
 127 int64_t vcpu_dirty_rate_get(int cpu_index)
 128 {
 129     DirtyRateVcpu *rates = vcpu_dirty_rate_stat->stat.rates;
 130     return qatomic_read_i64(&rates[cpu_index].dirty_rate);
 131 }
 132
 133 void vcpu_dirty_rate_stat_start(void)
 134 {
 135     if (qatomic_read(&vcpu_dirty_rate_stat->running)) {
 136         return;
 137     }
 138
 139     qatomic_set(&vcpu_dirty_rate_stat->running, 1);
 140     qemu_thread_create(&vcpu_dirty_rate_stat->thread,
 141                        "dirtyrate-stat",
 142                        vcpu_dirty_rate_stat_thread,
 143                        NULL,
 144                        QEMU_THREAD_JOINABLE);
 145 }
 146
 147 void vcpu_dirty_rate_stat_stop(void)
 148 {
 149     qatomic_set(&vcpu_dirty_rate_stat->running, 0);
 150     dirtylimit_state_unlock();
 151     qemu_mutex_unlock_iothread();
 152     qemu_thread_join(&vcpu_dirty_rate_stat->thread);
 153     qemu_mutex_lock_iothread();
 154     dirtylimit_state_lock();
 155 }
 156
 157 void vcpu_dirty_rate_stat_initialize(void)
 158 {
 159     MachineState *ms = MACHINE(qdev_get_machine());
 160     int max_cpus = ms->smp.max_cpus;
 161
 162     vcpu_dirty_rate_stat =
 163         g_malloc0(sizeof(*vcpu_dirty_rate_stat));
 164
 165     vcpu_dirty_rate_stat->stat.nvcpu = max_cpus;
 166     vcpu_dirty_rate_stat->stat.rates =
 167         g_new0(DirtyRateVcpu, max_cpus);
 168
 169     vcpu_dirty_rate_stat->running = false;
 170 }
 171
 172 void vcpu_dirty_rate_stat_finalize(void)
 173 {
 174     g_free(vcpu_dirty_rate_stat->stat.rates);
 175     vcpu_dirty_rate_stat->stat.rates = NULL;
 176
 177     g_free(vcpu_dirty_rate_stat);
 178     vcpu_dirty_rate_stat = NULL;
 179 }
 180
 181 void dirtylimit_state_lock(void)
 182 {
 183     qemu_mutex_lock(&dirtylimit_mutex);
 184 }
 185
 186 void dirtylimit_state_unlock(void)
 187 {
 188     qemu_mutex_unlock(&dirtylimit_mutex);
 189 }
 190
 191 static void
 192 __attribute__((__constructor__)) dirtylimit_mutex_init(void)
 193 {
 194     qemu_mutex_init(&dirtylimit_mutex);
 195 }
 196
 197 static inline VcpuDirtyLimitState *dirtylimit_vcpu_get_state(int cpu_index)
 198 {
 199     return &dirtylimit_state->states[cpu_index];
 200 }
 201
 202 void dirtylimit_state_initialize(void)
 203 {
 204     MachineState *ms = MACHINE(qdev_get_machine());
 205     int max_cpus = ms->smp.max_cpus;
 206     int i;
 207
 208     dirtylimit_state = g_malloc0(sizeof(*dirtylimit_state));
 209
 210     dirtylimit_state->states =
 211             g_new0(VcpuDirtyLimitState, max_cpus);
 212
 213     for (i = 0; i < max_cpus; i++) {
 214         dirtylimit_state->states[i].cpu_index = i;
 215     }
 216
 217     dirtylimit_state->max_cpus = max_cpus;
 218     trace_dirtylimit_state_initialize(max_cpus);
 219 }
 220
 221 void dirtylimit_state_finalize(void)
 222 {
 223     g_free(dirtylimit_state->states);
 224     dirtylimit_state->states = NULL;
 225
 226     g_free(dirtylimit_state);
 227     dirtylimit_state = NULL;
 228
 229     trace_dirtylimit_state_finalize();
 230 }
 231
 232 bool dirtylimit_in_service(void)
 233 {
 234     return !!dirtylimit_state;
 235 }
 236
 237 bool dirtylimit_vcpu_index_valid(int cpu_index)
 238 {
 239     MachineState *ms = MACHINE(qdev_get_machine());
 240
 241     return !(cpu_index < 0 ||
 242              cpu_index >= ms->smp.max_cpus);
 243 }
 244
 245 static uint64_t dirtylimit_dirty_ring_full_time(uint64_t dirtyrate)
 246 {
 247     static uint64_t max_dirtyrate;
 248     uint64_t dirty_ring_size_MiB;
 249
 250     dirty_ring_size_MiB = qemu_target_pages_to_MiB(kvm_dirty_ring_size());
 251
 252     if (max_dirtyrate < dirtyrate) {
 253         max_dirtyrate = dirtyrate;
 254     }
 255
 256     return dirty_ring_size_MiB * 1000000 / max_dirtyrate;
 257 }
 258
 259 static inline bool dirtylimit_done(uint64_t quota,
 260                                    uint64_t current)
 261 {
 262     uint64_t min, max;
 263
 264     min = MIN(quota, current);
 265     max = MAX(quota, current);
 266
 267     return ((max - min) <= DIRTYLIMIT_TOLERANCE_RANGE) ? true : false;
 268 }
 269
 270 static inline bool
 271 dirtylimit_need_linear_adjustment(uint64_t quota,
 272                                   uint64_t current)
 273 {
 274     uint64_t min, max;
 275
 276     min = MIN(quota, current);
 277     max = MAX(quota, current);
 278
 279     return ((max - min) * 100 / max) > DIRTYLIMIT_LINEAR_ADJUSTMENT_PCT;
 280 }
 281
 282 static void dirtylimit_set_throttle(CPUState *cpu,
 283                                     uint64_t quota,
 284                                     uint64_t current)
 285 {
 286     int64_t ring_full_time_us = 0;
 287     uint64_t sleep_pct = 0;
 288     uint64_t throttle_us = 0;
 289
 290     if (current == 0) {
 291         cpu->throttle_us_per_full = 0;
 292         return;
 293     }
 294
 295     ring_full_time_us = dirtylimit_dirty_ring_full_time(current);
 296
 297     if (dirtylimit_need_linear_adjustment(quota, current)) {
 298         if (quota < current) {
 299             sleep_pct = (current - quota) * 100 / current;
 300             throttle_us =
 301                 ring_full_time_us * sleep_pct / (double)(100 - sleep_pct);
 302             cpu->throttle_us_per_full += throttle_us;
 303         } else {
 304             sleep_pct = (quota - current) * 100 / quota;
 305             throttle_us =
 306                 ring_full_time_us * sleep_pct / (double)(100 - sleep_pct);
 307             cpu->throttle_us_per_full -= throttle_us;
 308         }
 309
 310         trace_dirtylimit_throttle_pct(cpu->cpu_index,
 311                                       sleep_pct,
 312                                       throttle_us);
 313     } else {
 314         if (quota < current) {
 315             cpu->throttle_us_per_full += ring_full_time_us / 10;
 316         } else {
 317             cpu->throttle_us_per_full -= ring_full_time_us / 10;
 318         }
 319     }
 320
 321     /*
 322      * TODO: in the big kvm_dirty_ring_size case (eg: 65536, or other scenario),
 323      *       current dirty page rate may never reach the quota, we should stop
 324      *       increasing sleep time?
 325      */
 326     cpu->throttle_us_per_full = MIN(cpu->throttle_us_per_full,
 327         ring_full_time_us * DIRTYLIMIT_THROTTLE_PCT_MAX);
 328
 329     cpu->throttle_us_per_full = MAX(cpu->throttle_us_per_full, 0);
 330 }
 331
 332 static void dirtylimit_adjust_throttle(CPUState *cpu)
 333 {
 334     uint64_t quota = 0;
 335     uint64_t current = 0;
 336     int cpu_index = cpu->cpu_index;
 337
 338     quota = dirtylimit_vcpu_get_state(cpu_index)->quota;
 339     current = vcpu_dirty_rate_get(cpu_index);
 340
 341     if (!dirtylimit_done(quota, current)) {
 342         dirtylimit_set_throttle(cpu, quota, current);
 343     }
 344
 345     return;
 346 }
 347
 348 void dirtylimit_process(void)
 349 {
 350     CPUState *cpu;
 351
 352     if (!qatomic_read(&dirtylimit_quit)) {
 353         dirtylimit_state_lock();
 354
 355         if (!dirtylimit_in_service()) {
 356             dirtylimit_state_unlock();
 357             return;
 358         }
 359
 360         CPU_FOREACH(cpu) {
 361             if (!dirtylimit_vcpu_get_state(cpu->cpu_index)->enabled) {
 362                 continue;
 363             }
 364             dirtylimit_adjust_throttle(cpu);
 365         }
 366         dirtylimit_state_unlock();
 367     }
 368 }
 369
 370 void dirtylimit_change(bool start)
 371 {
 372     if (start) {
 373         qatomic_set(&dirtylimit_quit, 0);
 374     } else {
 375         qatomic_set(&dirtylimit_quit, 1);
 376     }
 377 }
 378
 379 void dirtylimit_set_vcpu(int cpu_index,
 380                          uint64_t quota,
 381                          bool enable)
 382 {
 383     trace_dirtylimit_set_vcpu(cpu_index, quota);
 384
 385     if (enable) {
 386         dirtylimit_state->states[cpu_index].quota = quota;
 387         if (!dirtylimit_vcpu_get_state(cpu_index)->enabled) {
 388             dirtylimit_state->limited_nvcpu++;
 389         }
 390     } else {
 391         dirtylimit_state->states[cpu_index].quota = 0;
 392         if (dirtylimit_state->states[cpu_index].enabled) {
 393             dirtylimit_state->limited_nvcpu--;
 394         }
 395     }
 396
 397     dirtylimit_state->states[cpu_index].enabled = enable;
 398 }
 399
 400 void dirtylimit_set_all(uint64_t quota,
 401                         bool enable)
 402 {
 403     MachineState *ms = MACHINE(qdev_get_machine());
 404     int max_cpus = ms->smp.max_cpus;
 405     int i;
 406
 407     for (i = 0; i < max_cpus; i++) {
 408         dirtylimit_set_vcpu(i, quota, enable);
 409     }
 410 }
 411
 412 void dirtylimit_vcpu_execute(CPUState *cpu)
 413 {
 414     if (dirtylimit_in_service() &&
 415         dirtylimit_vcpu_get_state(cpu->cpu_index)->enabled &&
 416         cpu->throttle_us_per_full) {
 417         trace_dirtylimit_vcpu_execute(cpu->cpu_index,
 418                 cpu->throttle_us_per_full);
 419         usleep(cpu->throttle_us_per_full);
 420     }
 421 }
 422
 423 static void dirtylimit_init(void)
 424 {
 425     dirtylimit_state_initialize();
 426     dirtylimit_change(true);
 427     vcpu_dirty_rate_stat_initialize();
 428     vcpu_dirty_rate_stat_start();
 429 }
 430
 431 static void dirtylimit_cleanup(void)
 432 {
 433     vcpu_dirty_rate_stat_stop();
 434     vcpu_dirty_rate_stat_finalize();
 435     dirtylimit_change(false);
 436     dirtylimit_state_finalize();
 437 }
 438
 439 /*
 440  * dirty page rate limit is not allowed to set if migration
 441  * is running with dirty-limit capability enabled.
 442  */
 443 static bool dirtylimit_is_allowed(void)
 444 {
 445     MigrationState *ms = migrate_get_current();
 446
 447     if (migration_is_running(ms->state) &&
 448         (!qemu_thread_is_self(&ms->thread)) &&
 449         migrate_dirty_limit() &&
 450         dirtylimit_in_service()) {
 451         return false;
 452     }
 453     return true;
 454 }
 455
 456 void qmp_cancel_vcpu_dirty_limit(bool has_cpu_index,
 457                                  int64_t cpu_index,
 458                                  Error **errp)
 459 {
 460     if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
 461         return;
 462     }
 463
 464     if (has_cpu_index && !dirtylimit_vcpu_index_valid(cpu_index)) {
 465         error_setg(errp, "incorrect cpu index specified");
 466         return;
 467     }
 468
 469     if (!dirtylimit_is_allowed()) {
 470         error_setg(errp, "can't cancel dirty page rate limit while"
 471                    " migration is running");
 472         return;
 473     }
 474
 475     if (!dirtylimit_in_service()) {
 476         return;
 477     }
 478
 479     dirtylimit_state_lock();
 480
 481     if (has_cpu_index) {
 482         dirtylimit_set_vcpu(cpu_index, 0, false);
 483     } else {
 484         dirtylimit_set_all(0, false);
 485     }
 486
 487     if (!dirtylimit_state->limited_nvcpu) {
 488         dirtylimit_cleanup();
 489     }
 490
 491     dirtylimit_state_unlock();
 492 }
 493
 494 void hmp_cancel_vcpu_dirty_limit(Monitor *mon, const QDict *qdict)
 495 {
 496     int64_t cpu_index = qdict_get_try_int(qdict, "cpu_index", -1);
 497     Error *err = NULL;
 498
 499     qmp_cancel_vcpu_dirty_limit(!!(cpu_index != -1), cpu_index, &err);
 500     if (err) {
 501         hmp_handle_error(mon, err);
 502         return;
 503     }
 504
 505     monitor_printf(mon, "[Please use 'info vcpu_dirty_limit' to query "
 506                    "dirty limit for virtual CPU]\n");
 507 }
 508
 509 void qmp_set_vcpu_dirty_limit(bool has_cpu_index,
 510                               int64_t cpu_index,
 511                               uint64_t dirty_rate,
 512                               Error **errp)
 513 {
 514     if (!kvm_enabled() || !kvm_dirty_ring_enabled()) {
 515         error_setg(errp, "dirty page limit feature requires KVM with"
 516                    " accelerator property 'dirty-ring-size' set'");
 517         return;
 518     }
 519
 520     if (has_cpu_index && !dirtylimit_vcpu_index_valid(cpu_index)) {
 521         error_setg(errp, "incorrect cpu index specified");
 522         return;
 523     }
 524
 525     if (!dirtylimit_is_allowed()) {
 526         error_setg(errp, "can't set dirty page rate limit while"
 527                    " migration is running");
 528         return;
 529     }
 530
 531     if (!dirty_rate) {
 532         qmp_cancel_vcpu_dirty_limit(has_cpu_index, cpu_index, errp);
 533         return;
 534     }
 535
 536     dirtylimit_state_lock();
 537
 538     if (!dirtylimit_in_service()) {
 539         dirtylimit_init();
 540     }
 541
 542     if (has_cpu_index) {
 543         dirtylimit_set_vcpu(cpu_index, dirty_rate, true);
 544     } else {
 545         dirtylimit_set_all(dirty_rate, true);
 546     }
 547
 548     dirtylimit_state_unlock();
 549 }
 550
 551 void hmp_set_vcpu_dirty_limit(Monitor *mon, const QDict *qdict)
 552 {
 553     int64_t dirty_rate = qdict_get_int(qdict, "dirty_rate");
 554     int64_t cpu_index = qdict_get_try_int(qdict, "cpu_index", -1);
 555     Error *err = NULL;
 556
 557     if (dirty_rate < 0) {
 558         error_setg(&err, "invalid dirty page limit %" PRId64, dirty_rate);
 559         goto out;
 560     }
 561
 562     qmp_set_vcpu_dirty_limit(!!(cpu_index != -1), cpu_index, dirty_rate, &err);
 563
 564 out:
 565     hmp_handle_error(mon, err);
 566 }
 567
 568 /* Return the max throttle time of each virtual CPU */
 569 uint64_t dirtylimit_throttle_time_per_round(void)
 570 {
 571     CPUState *cpu;
 572     int64_t max = 0;
 573
 574     CPU_FOREACH(cpu) {
 575         if (cpu->throttle_us_per_full > max) {
 576             max = cpu->throttle_us_per_full;
 577         }
 578     }
 579
 580     return max;
 581 }
 582
 583 /*
 584  * Estimate average dirty ring full time of each virtaul CPU.
 585  * Return 0 if guest doesn't dirty memory.
 586  */
 587 uint64_t dirtylimit_ring_full_time(void)
 588 {
 589     CPUState *cpu;
 590     uint64_t curr_rate = 0;
 591     int nvcpus = 0;
 592
 593     CPU_FOREACH(cpu) {
 594         if (cpu->running) {
 595             nvcpus++;
 596             curr_rate += vcpu_dirty_rate_get(cpu->cpu_index);
 597         }
 598     }
 599
 600     if (!curr_rate || !nvcpus) {
 601         return 0;
 602     }
 603
 604     return dirtylimit_dirty_ring_full_time(curr_rate / nvcpus);
 605 }
 606
 607 static struct DirtyLimitInfo *dirtylimit_query_vcpu(int cpu_index)
 608 {
 609     DirtyLimitInfo *info = NULL;
 610
 611     info = g_malloc0(sizeof(*info));
 612     info->cpu_index = cpu_index;
 613     info->limit_rate = dirtylimit_vcpu_get_state(cpu_index)->quota;
 614     info->current_rate = vcpu_dirty_rate_get(cpu_index);
 615
 616     return info;
 617 }
 618
 619 static struct DirtyLimitInfoList *dirtylimit_query_all(void)
 620 {
 621     int i, index;
 622     DirtyLimitInfo *info = NULL;
 623     DirtyLimitInfoList *head = NULL, **tail = &head;
 624
 625     dirtylimit_state_lock();
 626
 627     if (!dirtylimit_in_service()) {
 628         dirtylimit_state_unlock();
 629         return NULL;
 630     }
 631
 632     for (i = 0; i < dirtylimit_state->max_cpus; i++) {
 633         index = dirtylimit_state->states[i].cpu_index;
 634         if (dirtylimit_vcpu_get_state(index)->enabled) {
 635             info = dirtylimit_query_vcpu(index);
 636             QAPI_LIST_APPEND(tail, info);
 637         }
 638     }
 639
 640     dirtylimit_state_unlock();
 641
 642     return head;
 643 }
 644
 645 struct DirtyLimitInfoList *qmp_query_vcpu_dirty_limit(Error **errp)
 646 {
 647     if (!dirtylimit_in_service()) {
 648         return NULL;
 649     }
 650
 651     return dirtylimit_query_all();
 652 }
 653
 654 void hmp_info_vcpu_dirty_limit(Monitor *mon, const QDict *qdict)
 655 {
 656     DirtyLimitInfoList *info;
 657     g_autoptr(DirtyLimitInfoList) head = NULL;
 658     Error *err = NULL;
 659
 660     if (!dirtylimit_in_service()) {
 661         monitor_printf(mon, "Dirty page limit not enabled!\n");
 662         return;
 663     }
 664
 665     head = qmp_query_vcpu_dirty_limit(&err);
 666     if (err) {
 667         hmp_handle_error(mon, err);
 668         return;
 669     }
 670
 671     for (info = head; info != NULL; info = info->next) {
 672         monitor_printf(mon, "vcpu[%"PRIi64"], limit rate %"PRIi64 " (MB/s),"
 673                             " current rate %"PRIi64 " (MB/s)\n",
 674                             info->value->cpu_index,
 675                             info->value->limit_rate,
 676                             info->value->current_rate);
 677     }
 678 }