migration/migration.c

   1 /*
   2  * QEMU live migration
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <[email protected]>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "qemu/main-loop.h"
  18 #include "migration/migration.h"
  19 #include "monitor/monitor.h"
  20 #include "migration/qemu-file.h"
  21 #include "sysemu/sysemu.h"
  22 #include "block/block.h"
  23 #include "qemu/sockets.h"
  24 #include "migration/block.h"
  25 #include "qemu/thread.h"
  26 #include "qmp-commands.h"
  27 #include "trace.h"
  28
  29 enum {
  30     MIG_STATE_ERROR = -1,
  31     MIG_STATE_NONE,
  32     MIG_STATE_SETUP,
  33     MIG_STATE_CANCELLING,
  34     MIG_STATE_CANCELLED,
  35     MIG_STATE_ACTIVE,
  36     MIG_STATE_COMPLETED,
  37 };
  38
  39 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
  40
  41 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
  42  * data. */
  43 #define BUFFER_DELAY     100
  44 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
  45
  46 /* Migration XBZRLE default cache size */
  47 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
  48
  49 static NotifierList migration_state_notifiers =
  50     NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  51
  52 static bool deferred_incoming;
  53
  54 /* When we add fault tolerance, we could have several
  55    migrations at once.  For now we don't need to add
  56    dynamic creation of migration */
  57
  58 MigrationState *migrate_get_current(void)
  59 {
  60     static MigrationState current_migration = {
  61         .state = MIG_STATE_NONE,
  62         .bandwidth_limit = MAX_THROTTLE,
  63         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
  64         .mbps = -1,
  65     };
  66
  67     return &current_migration;
  68 }
  69
  70 /*
  71  * Called on -incoming with a defer: uri.
  72  * The migration can be started later after any parameters have been
  73  * changed.
  74  */
  75 static void deferred_incoming_migration(Error **errp)
  76 {
  77     if (deferred_incoming) {
  78         error_setg(errp, "Incoming migration already deferred");
  79     }
  80     deferred_incoming = true;
  81 }
  82
  83 void qemu_start_incoming_migration(const char *uri, Error **errp)
  84 {
  85     const char *p;
  86
  87     if (!strcmp(uri, "defer")) {
  88         deferred_incoming_migration(errp);
  89     } else if (strstart(uri, "tcp:", &p)) {
  90         tcp_start_incoming_migration(p, errp);
  91 #ifdef CONFIG_RDMA
  92     } else if (strstart(uri, "rdma:", &p)) {
  93         rdma_start_incoming_migration(p, errp);
  94 #endif
  95 #if !defined(WIN32)
  96     } else if (strstart(uri, "exec:", &p)) {
  97         exec_start_incoming_migration(p, errp);
  98     } else if (strstart(uri, "unix:", &p)) {
  99         unix_start_incoming_migration(p, errp);
 100     } else if (strstart(uri, "fd:", &p)) {
 101         fd_start_incoming_migration(p, errp);
 102 #endif
 103     } else {
 104         error_setg(errp, "unknown migration protocol: %s", uri);
 105     }
 106 }
 107
 108 static void process_incoming_migration_co(void *opaque)
 109 {
 110     QEMUFile *f = opaque;
 111     Error *local_err = NULL;
 112     int ret;
 113
 114     ret = qemu_loadvm_state(f);
 115     qemu_fclose(f);
 116     free_xbzrle_decoded_buf();
 117     if (ret < 0) {
 118         error_report("load of migration failed: %s", strerror(-ret));
 119         exit(EXIT_FAILURE);
 120     }
 121     qemu_announce_self();
 122
 123     /* Make sure all file formats flush their mutable metadata */
 124     bdrv_invalidate_cache_all(&local_err);
 125     if (local_err) {
 126         error_report_err(local_err);
 127         exit(EXIT_FAILURE);
 128     }
 129
 130     if (autostart) {
 131         vm_start();
 132     } else {
 133         runstate_set(RUN_STATE_PAUSED);
 134     }
 135 }
 136
 137 void process_incoming_migration(QEMUFile *f)
 138 {
 139     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 140     int fd = qemu_get_fd(f);
 141
 142     assert(fd != -1);
 143     qemu_set_nonblock(fd);
 144     qemu_coroutine_enter(co, f);
 145 }
 146
 147 /* amount of nanoseconds we are willing to wait for migration to be down.
 148  * the choice of nanoseconds is because it is the maximum resolution that
 149  * get_clock() can achieve. It is an internal measure. All user-visible
 150  * units must be in seconds */
 151 static uint64_t max_downtime = 300000000;
 152
 153 uint64_t migrate_max_downtime(void)
 154 {
 155     return max_downtime;
 156 }
 157
 158 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 159 {
 160     MigrationCapabilityStatusList *head = NULL;
 161     MigrationCapabilityStatusList *caps;
 162     MigrationState *s = migrate_get_current();
 163     int i;
 164
 165     caps = NULL; /* silence compiler warning */
 166     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 167         if (head == NULL) {
 168             head = g_malloc0(sizeof(*caps));
 169             caps = head;
 170         } else {
 171             caps->next = g_malloc0(sizeof(*caps));
 172             caps = caps->next;
 173         }
 174         caps->value =
 175             g_malloc(sizeof(*caps->value));
 176         caps->value->capability = i;
 177         caps->value->state = s->enabled_capabilities[i];
 178     }
 179
 180     return head;
 181 }
 182
 183 static void get_xbzrle_cache_stats(MigrationInfo *info)
 184 {
 185     if (migrate_use_xbzrle()) {
 186         info->has_xbzrle_cache = true;
 187         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 188         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 189         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 190         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 191         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 192         info->xbzrle_cache->cache_miss_rate = xbzrle_mig_cache_miss_rate();
 193         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 194     }
 195 }
 196
 197 MigrationInfo *qmp_query_migrate(Error **errp)
 198 {
 199     MigrationInfo *info = g_malloc0(sizeof(*info));
 200     MigrationState *s = migrate_get_current();
 201
 202     switch (s->state) {
 203     case MIG_STATE_NONE:
 204         /* no migration has happened ever */
 205         break;
 206     case MIG_STATE_SETUP:
 207         info->has_status = true;
 208         info->status = g_strdup("setup");
 209         info->has_total_time = false;
 210         break;
 211     case MIG_STATE_ACTIVE:
 212     case MIG_STATE_CANCELLING:
 213         info->has_status = true;
 214         info->status = g_strdup("active");
 215         info->has_total_time = true;
 216         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
 217             - s->total_time;
 218         info->has_expected_downtime = true;
 219         info->expected_downtime = s->expected_downtime;
 220         info->has_setup_time = true;
 221         info->setup_time = s->setup_time;
 222
 223         info->has_ram = true;
 224         info->ram = g_malloc0(sizeof(*info->ram));
 225         info->ram->transferred = ram_bytes_transferred();
 226         info->ram->remaining = ram_bytes_remaining();
 227         info->ram->total = ram_bytes_total();
 228         info->ram->duplicate = dup_mig_pages_transferred();
 229         info->ram->skipped = skipped_mig_pages_transferred();
 230         info->ram->normal = norm_mig_pages_transferred();
 231         info->ram->normal_bytes = norm_mig_bytes_transferred();
 232         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 233         info->ram->mbps = s->mbps;
 234         info->ram->dirty_sync_count = s->dirty_sync_count;
 235
 236         if (blk_mig_active()) {
 237             info->has_disk = true;
 238             info->disk = g_malloc0(sizeof(*info->disk));
 239             info->disk->transferred = blk_mig_bytes_transferred();
 240             info->disk->remaining = blk_mig_bytes_remaining();
 241             info->disk->total = blk_mig_bytes_total();
 242         }
 243
 244         get_xbzrle_cache_stats(info);
 245         break;
 246     case MIG_STATE_COMPLETED:
 247         get_xbzrle_cache_stats(info);
 248
 249         info->has_status = true;
 250         info->status = g_strdup("completed");
 251         info->has_total_time = true;
 252         info->total_time = s->total_time;
 253         info->has_downtime = true;
 254         info->downtime = s->downtime;
 255         info->has_setup_time = true;
 256         info->setup_time = s->setup_time;
 257
 258         info->has_ram = true;
 259         info->ram = g_malloc0(sizeof(*info->ram));
 260         info->ram->transferred = ram_bytes_transferred();
 261         info->ram->remaining = 0;
 262         info->ram->total = ram_bytes_total();
 263         info->ram->duplicate = dup_mig_pages_transferred();
 264         info->ram->skipped = skipped_mig_pages_transferred();
 265         info->ram->normal = norm_mig_pages_transferred();
 266         info->ram->normal_bytes = norm_mig_bytes_transferred();
 267         info->ram->mbps = s->mbps;
 268         info->ram->dirty_sync_count = s->dirty_sync_count;
 269         break;
 270     case MIG_STATE_ERROR:
 271         info->has_status = true;
 272         info->status = g_strdup("failed");
 273         break;
 274     case MIG_STATE_CANCELLED:
 275         info->has_status = true;
 276         info->status = g_strdup("cancelled");
 277         break;
 278     }
 279
 280     return info;
 281 }
 282
 283 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 284                                   Error **errp)
 285 {
 286     MigrationState *s = migrate_get_current();
 287     MigrationCapabilityStatusList *cap;
 288
 289     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
 290         error_set(errp, QERR_MIGRATION_ACTIVE);
 291         return;
 292     }
 293
 294     for (cap = params; cap; cap = cap->next) {
 295         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 296     }
 297 }
 298
 299 /* shared migration helpers */
 300
 301 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 302 {
 303     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
 304         trace_migrate_set_state(new_state);
 305     }
 306 }
 307
 308 static void migrate_fd_cleanup(void *opaque)
 309 {
 310     MigrationState *s = opaque;
 311
 312     qemu_bh_delete(s->cleanup_bh);
 313     s->cleanup_bh = NULL;
 314
 315     if (s->file) {
 316         trace_migrate_fd_cleanup();
 317         qemu_mutex_unlock_iothread();
 318         qemu_thread_join(&s->thread);
 319         qemu_mutex_lock_iothread();
 320
 321         qemu_fclose(s->file);
 322         s->file = NULL;
 323     }
 324
 325     assert(s->state != MIG_STATE_ACTIVE);
 326
 327     if (s->state != MIG_STATE_COMPLETED) {
 328         qemu_savevm_state_cancel();
 329         if (s->state == MIG_STATE_CANCELLING) {
 330             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
 331         }
 332     }
 333
 334     notifier_list_notify(&migration_state_notifiers, s);
 335 }
 336
 337 void migrate_fd_error(MigrationState *s)
 338 {
 339     trace_migrate_fd_error();
 340     assert(s->file == NULL);
 341     s->state = MIG_STATE_ERROR;
 342     trace_migrate_set_state(MIG_STATE_ERROR);
 343     notifier_list_notify(&migration_state_notifiers, s);
 344 }
 345
 346 static void migrate_fd_cancel(MigrationState *s)
 347 {
 348     int old_state ;
 349     QEMUFile *f = migrate_get_current()->file;
 350     trace_migrate_fd_cancel();
 351
 352     do {
 353         old_state = s->state;
 354         if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
 355             break;
 356         }
 357         migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
 358     } while (s->state != MIG_STATE_CANCELLING);
 359
 360     /*
 361      * If we're unlucky the migration code might be stuck somewhere in a
 362      * send/write while the network has failed and is waiting to timeout;
 363      * if we've got shutdown(2) available then we can force it to quit.
 364      * The outgoing qemu file gets closed in migrate_fd_cleanup that is
 365      * called in a bh, so there is no race against this cancel.
 366      */
 367     if (s->state == MIG_STATE_CANCELLING && f) {
 368         qemu_file_shutdown(f);
 369     }
 370 }
 371
 372 void add_migration_state_change_notifier(Notifier *notify)
 373 {
 374     notifier_list_add(&migration_state_notifiers, notify);
 375 }
 376
 377 void remove_migration_state_change_notifier(Notifier *notify)
 378 {
 379     notifier_remove(notify);
 380 }
 381
 382 bool migration_in_setup(MigrationState *s)
 383 {
 384     return s->state == MIG_STATE_SETUP;
 385 }
 386
 387 bool migration_has_finished(MigrationState *s)
 388 {
 389     return s->state == MIG_STATE_COMPLETED;
 390 }
 391
 392 bool migration_has_failed(MigrationState *s)
 393 {
 394     return (s->state == MIG_STATE_CANCELLED ||
 395             s->state == MIG_STATE_ERROR);
 396 }
 397
 398 static MigrationState *migrate_init(const MigrationParams *params)
 399 {
 400     MigrationState *s = migrate_get_current();
 401     int64_t bandwidth_limit = s->bandwidth_limit;
 402     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 403     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 404
 405     memcpy(enabled_capabilities, s->enabled_capabilities,
 406            sizeof(enabled_capabilities));
 407
 408     memset(s, 0, sizeof(*s));
 409     s->params = *params;
 410     memcpy(s->enabled_capabilities, enabled_capabilities,
 411            sizeof(enabled_capabilities));
 412     s->xbzrle_cache_size = xbzrle_cache_size;
 413
 414     s->bandwidth_limit = bandwidth_limit;
 415     s->state = MIG_STATE_SETUP;
 416     trace_migrate_set_state(MIG_STATE_SETUP);
 417
 418     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 419     return s;
 420 }
 421
 422 static GSList *migration_blockers;
 423
 424 void migrate_add_blocker(Error *reason)
 425 {
 426     migration_blockers = g_slist_prepend(migration_blockers, reason);
 427 }
 428
 429 void migrate_del_blocker(Error *reason)
 430 {
 431     migration_blockers = g_slist_remove(migration_blockers, reason);
 432 }
 433
 434 void qmp_migrate_incoming(const char *uri, Error **errp)
 435 {
 436     Error *local_err = NULL;
 437
 438     if (!deferred_incoming) {
 439         error_setg(errp, "'-incoming defer' is required for migrate_incoming");
 440         return;
 441     }
 442
 443     qemu_start_incoming_migration(uri, &local_err);
 444
 445     if (local_err) {
 446         error_propagate(errp, local_err);
 447         return;
 448     }
 449
 450     deferred_incoming = false;
 451 }
 452
 453 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 454                  bool has_inc, bool inc, bool has_detach, bool detach,
 455                  Error **errp)
 456 {
 457     Error *local_err = NULL;
 458     MigrationState *s = migrate_get_current();
 459     MigrationParams params;
 460     const char *p;
 461
 462     params.blk = has_blk && blk;
 463     params.shared = has_inc && inc;
 464
 465     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
 466         s->state == MIG_STATE_CANCELLING) {
 467         error_set(errp, QERR_MIGRATION_ACTIVE);
 468         return;
 469     }
 470
 471     if (runstate_check(RUN_STATE_INMIGRATE)) {
 472         error_setg(errp, "Guest is waiting for an incoming migration");
 473         return;
 474     }
 475
 476     if (qemu_savevm_state_blocked(errp)) {
 477         return;
 478     }
 479
 480     if (migration_blockers) {
 481         *errp = error_copy(migration_blockers->data);
 482         return;
 483     }
 484
 485     s = migrate_init(&params);
 486
 487     if (strstart(uri, "tcp:", &p)) {
 488         tcp_start_outgoing_migration(s, p, &local_err);
 489 #ifdef CONFIG_RDMA
 490     } else if (strstart(uri, "rdma:", &p)) {
 491         rdma_start_outgoing_migration(s, p, &local_err);
 492 #endif
 493 #if !defined(WIN32)
 494     } else if (strstart(uri, "exec:", &p)) {
 495         exec_start_outgoing_migration(s, p, &local_err);
 496     } else if (strstart(uri, "unix:", &p)) {
 497         unix_start_outgoing_migration(s, p, &local_err);
 498     } else if (strstart(uri, "fd:", &p)) {
 499         fd_start_outgoing_migration(s, p, &local_err);
 500 #endif
 501     } else {
 502         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 503         s->state = MIG_STATE_ERROR;
 504         return;
 505     }
 506
 507     if (local_err) {
 508         migrate_fd_error(s);
 509         error_propagate(errp, local_err);
 510         return;
 511     }
 512 }
 513
 514 void qmp_migrate_cancel(Error **errp)
 515 {
 516     migrate_fd_cancel(migrate_get_current());
 517 }
 518
 519 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 520 {
 521     MigrationState *s = migrate_get_current();
 522     int64_t new_size;
 523
 524     /* Check for truncation */
 525     if (value != (size_t)value) {
 526         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 527                   "exceeding address space");
 528         return;
 529     }
 530
 531     /* Cache should not be larger than guest ram size */
 532     if (value > ram_bytes_total()) {
 533         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 534                   "exceeds guest ram size ");
 535         return;
 536     }
 537
 538     new_size = xbzrle_cache_resize(value);
 539     if (new_size < 0) {
 540         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 541                   "is smaller than page size");
 542         return;
 543     }
 544
 545     s->xbzrle_cache_size = new_size;
 546 }
 547
 548 int64_t qmp_query_migrate_cache_size(Error **errp)
 549 {
 550     return migrate_xbzrle_cache_size();
 551 }
 552
 553 void qmp_migrate_set_speed(int64_t value, Error **errp)
 554 {
 555     MigrationState *s;
 556
 557     if (value < 0) {
 558         value = 0;
 559     }
 560     if (value > SIZE_MAX) {
 561         value = SIZE_MAX;
 562     }
 563
 564     s = migrate_get_current();
 565     s->bandwidth_limit = value;
 566     if (s->file) {
 567         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
 568     }
 569 }
 570
 571 void qmp_migrate_set_downtime(double value, Error **errp)
 572 {
 573     value *= 1e9;
 574     value = MAX(0, MIN(UINT64_MAX, value));
 575     max_downtime = (uint64_t)value;
 576 }
 577
 578 bool migrate_rdma_pin_all(void)
 579 {
 580     MigrationState *s;
 581
 582     s = migrate_get_current();
 583
 584     return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
 585 }
 586
 587 bool migrate_auto_converge(void)
 588 {
 589     MigrationState *s;
 590
 591     s = migrate_get_current();
 592
 593     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
 594 }
 595
 596 bool migrate_zero_blocks(void)
 597 {
 598     MigrationState *s;
 599
 600     s = migrate_get_current();
 601
 602     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 603 }
 604
 605 int migrate_use_xbzrle(void)
 606 {
 607     MigrationState *s;
 608
 609     s = migrate_get_current();
 610
 611     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 612 }
 613
 614 int64_t migrate_xbzrle_cache_size(void)
 615 {
 616     MigrationState *s;
 617
 618     s = migrate_get_current();
 619
 620     return s->xbzrle_cache_size;
 621 }
 622
 623 /* migration thread support */
 624
 625 static void *migration_thread(void *opaque)
 626 {
 627     MigrationState *s = opaque;
 628     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 629     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 630     int64_t initial_bytes = 0;
 631     int64_t max_size = 0;
 632     int64_t start_time = initial_time;
 633     bool old_vm_running = false;
 634
 635     qemu_savevm_state_begin(s->file, &s->params);
 636
 637     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
 638     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
 639
 640     while (s->state == MIG_STATE_ACTIVE) {
 641         int64_t current_time;
 642         uint64_t pending_size;
 643
 644         if (!qemu_file_rate_limit(s->file)) {
 645             pending_size = qemu_savevm_state_pending(s->file, max_size);
 646             trace_migrate_pending(pending_size, max_size);
 647             if (pending_size && pending_size >= max_size) {
 648                 qemu_savevm_state_iterate(s->file);
 649             } else {
 650                 int ret;
 651
 652                 qemu_mutex_lock_iothread();
 653                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 654                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 655                 old_vm_running = runstate_is_running();
 656
 657                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 658                 if (ret >= 0) {
 659                     qemu_file_set_rate_limit(s->file, INT64_MAX);
 660                     qemu_savevm_state_complete(s->file);
 661                 }
 662                 qemu_mutex_unlock_iothread();
 663
 664                 if (ret < 0) {
 665                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 666                     break;
 667                 }
 668
 669                 if (!qemu_file_get_error(s->file)) {
 670                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
 671                     break;
 672                 }
 673             }
 674         }
 675
 676         if (qemu_file_get_error(s->file)) {
 677             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 678             break;
 679         }
 680         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 681         if (current_time >= initial_time + BUFFER_DELAY) {
 682             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
 683             uint64_t time_spent = current_time - initial_time;
 684             double bandwidth = transferred_bytes / time_spent;
 685             max_size = bandwidth * migrate_max_downtime() / 1000000;
 686
 687             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
 688                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
 689
 690             trace_migrate_transferred(transferred_bytes, time_spent,
 691                                       bandwidth, max_size);
 692             /* if we haven't sent anything, we don't want to recalculate
 693                10000 is a small enough number for our purposes */
 694             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 695                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 696             }
 697
 698             qemu_file_reset_rate_limit(s->file);
 699             initial_time = current_time;
 700             initial_bytes = qemu_ftell(s->file);
 701         }
 702         if (qemu_file_rate_limit(s->file)) {
 703             /* usleep expects microseconds */
 704             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 705         }
 706     }
 707
 708     qemu_mutex_lock_iothread();
 709     if (s->state == MIG_STATE_COMPLETED) {
 710         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 711         uint64_t transferred_bytes = qemu_ftell(s->file);
 712         s->total_time = end_time - s->total_time;
 713         s->downtime = end_time - start_time;
 714         if (s->total_time) {
 715             s->mbps = (((double) transferred_bytes * 8.0) /
 716                        ((double) s->total_time)) / 1000;
 717         }
 718         runstate_set(RUN_STATE_POSTMIGRATE);
 719     } else {
 720         if (old_vm_running) {
 721             vm_start();
 722         }
 723     }
 724     qemu_bh_schedule(s->cleanup_bh);
 725     qemu_mutex_unlock_iothread();
 726
 727     return NULL;
 728 }
 729
 730 void migrate_fd_connect(MigrationState *s)
 731 {
 732     s->state = MIG_STATE_SETUP;
 733     trace_migrate_set_state(MIG_STATE_SETUP);
 734
 735     /* This is a best 1st approximation. ns to ms */
 736     s->expected_downtime = max_downtime/1000000;
 737     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 738
 739     qemu_file_set_rate_limit(s->file,
 740                              s->bandwidth_limit / XFER_LIMIT_RATIO);
 741
 742     /* Notify before starting migration thread */
 743     notifier_list_notify(&migration_state_notifiers, s);
 744
 745     qemu_thread_create(&s->thread, "migration", migration_thread, s,
 746                        QEMU_THREAD_JOINABLE);
 747 }