migration/migration.c

   1 /*
   2  * QEMU live migration
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   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         qerror_report_err(local_err);
 127         error_free(local_err);
 128         exit(EXIT_FAILURE);
 129     }
 130
 131     if (autostart) {
 132         vm_start();
 133     } else {
 134         runstate_set(RUN_STATE_PAUSED);
 135     }
 136 }
 137
 138 void process_incoming_migration(QEMUFile *f)
 139 {
 140     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 141     int fd = qemu_get_fd(f);
 142
 143     assert(fd != -1);
 144     qemu_set_nonblock(fd);
 145     qemu_coroutine_enter(co, f);
 146 }
 147
 148 /* amount of nanoseconds we are willing to wait for migration to be down.
 149  * the choice of nanoseconds is because it is the maximum resolution that
 150  * get_clock() can achieve. It is an internal measure. All user-visible
 151  * units must be in seconds */
 152 static uint64_t max_downtime = 300000000;
 153
 154 uint64_t migrate_max_downtime(void)
 155 {
 156     return max_downtime;
 157 }
 158
 159 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 160 {
 161     MigrationCapabilityStatusList *head = NULL;
 162     MigrationCapabilityStatusList *caps;
 163     MigrationState *s = migrate_get_current();
 164     int i;
 165
 166     caps = NULL; /* silence compiler warning */
 167     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 168         if (head == NULL) {
 169             head = g_malloc0(sizeof(*caps));
 170             caps = head;
 171         } else {
 172             caps->next = g_malloc0(sizeof(*caps));
 173             caps = caps->next;
 174         }
 175         caps->value =
 176             g_malloc(sizeof(*caps->value));
 177         caps->value->capability = i;
 178         caps->value->state = s->enabled_capabilities[i];
 179     }
 180
 181     return head;
 182 }
 183
 184 static void get_xbzrle_cache_stats(MigrationInfo *info)
 185 {
 186     if (migrate_use_xbzrle()) {
 187         info->has_xbzrle_cache = true;
 188         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 189         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 190         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 191         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 192         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 193         info->xbzrle_cache->cache_miss_rate = xbzrle_mig_cache_miss_rate();
 194         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 195     }
 196 }
 197
 198 MigrationInfo *qmp_query_migrate(Error **errp)
 199 {
 200     MigrationInfo *info = g_malloc0(sizeof(*info));
 201     MigrationState *s = migrate_get_current();
 202
 203     switch (s->state) {
 204     case MIG_STATE_NONE:
 205         /* no migration has happened ever */
 206         break;
 207     case MIG_STATE_SETUP:
 208         info->has_status = true;
 209         info->status = g_strdup("setup");
 210         info->has_total_time = false;
 211         break;
 212     case MIG_STATE_ACTIVE:
 213     case MIG_STATE_CANCELLING:
 214         info->has_status = true;
 215         info->status = g_strdup("active");
 216         info->has_total_time = true;
 217         info->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
 218             - s->total_time;
 219         info->has_expected_downtime = true;
 220         info->expected_downtime = s->expected_downtime;
 221         info->has_setup_time = true;
 222         info->setup_time = s->setup_time;
 223
 224         info->has_ram = true;
 225         info->ram = g_malloc0(sizeof(*info->ram));
 226         info->ram->transferred = ram_bytes_transferred();
 227         info->ram->remaining = ram_bytes_remaining();
 228         info->ram->total = ram_bytes_total();
 229         info->ram->duplicate = dup_mig_pages_transferred();
 230         info->ram->skipped = skipped_mig_pages_transferred();
 231         info->ram->normal = norm_mig_pages_transferred();
 232         info->ram->normal_bytes = norm_mig_bytes_transferred();
 233         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 234         info->ram->mbps = s->mbps;
 235         info->ram->dirty_sync_count = s->dirty_sync_count;
 236
 237         if (blk_mig_active()) {
 238             info->has_disk = true;
 239             info->disk = g_malloc0(sizeof(*info->disk));
 240             info->disk->transferred = blk_mig_bytes_transferred();
 241             info->disk->remaining = blk_mig_bytes_remaining();
 242             info->disk->total = blk_mig_bytes_total();
 243         }
 244
 245         get_xbzrle_cache_stats(info);
 246         break;
 247     case MIG_STATE_COMPLETED:
 248         get_xbzrle_cache_stats(info);
 249
 250         info->has_status = true;
 251         info->status = g_strdup("completed");
 252         info->has_total_time = true;
 253         info->total_time = s->total_time;
 254         info->has_downtime = true;
 255         info->downtime = s->downtime;
 256         info->has_setup_time = true;
 257         info->setup_time = s->setup_time;
 258
 259         info->has_ram = true;
 260         info->ram = g_malloc0(sizeof(*info->ram));
 261         info->ram->transferred = ram_bytes_transferred();
 262         info->ram->remaining = 0;
 263         info->ram->total = ram_bytes_total();
 264         info->ram->duplicate = dup_mig_pages_transferred();
 265         info->ram->skipped = skipped_mig_pages_transferred();
 266         info->ram->normal = norm_mig_pages_transferred();
 267         info->ram->normal_bytes = norm_mig_bytes_transferred();
 268         info->ram->mbps = s->mbps;
 269         info->ram->dirty_sync_count = s->dirty_sync_count;
 270         break;
 271     case MIG_STATE_ERROR:
 272         info->has_status = true;
 273         info->status = g_strdup("failed");
 274         break;
 275     case MIG_STATE_CANCELLED:
 276         info->has_status = true;
 277         info->status = g_strdup("cancelled");
 278         break;
 279     }
 280
 281     return info;
 282 }
 283
 284 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 285                                   Error **errp)
 286 {
 287     MigrationState *s = migrate_get_current();
 288     MigrationCapabilityStatusList *cap;
 289
 290     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP) {
 291         error_set(errp, QERR_MIGRATION_ACTIVE);
 292         return;
 293     }
 294
 295     for (cap = params; cap; cap = cap->next) {
 296         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 297     }
 298 }
 299
 300 /* shared migration helpers */
 301
 302 static void migrate_set_state(MigrationState *s, int old_state, int new_state)
 303 {
 304     if (atomic_cmpxchg(&s->state, old_state, new_state) == new_state) {
 305         trace_migrate_set_state(new_state);
 306     }
 307 }
 308
 309 static void migrate_fd_cleanup(void *opaque)
 310 {
 311     MigrationState *s = opaque;
 312
 313     qemu_bh_delete(s->cleanup_bh);
 314     s->cleanup_bh = NULL;
 315
 316     if (s->file) {
 317         trace_migrate_fd_cleanup();
 318         qemu_mutex_unlock_iothread();
 319         qemu_thread_join(&s->thread);
 320         qemu_mutex_lock_iothread();
 321
 322         qemu_fclose(s->file);
 323         s->file = NULL;
 324     }
 325
 326     assert(s->state != MIG_STATE_ACTIVE);
 327
 328     if (s->state != MIG_STATE_COMPLETED) {
 329         qemu_savevm_state_cancel();
 330         if (s->state == MIG_STATE_CANCELLING) {
 331             migrate_set_state(s, MIG_STATE_CANCELLING, MIG_STATE_CANCELLED);
 332         }
 333     }
 334
 335     notifier_list_notify(&migration_state_notifiers, s);
 336 }
 337
 338 void migrate_fd_error(MigrationState *s)
 339 {
 340     trace_migrate_fd_error();
 341     assert(s->file == NULL);
 342     s->state = MIG_STATE_ERROR;
 343     trace_migrate_set_state(MIG_STATE_ERROR);
 344     notifier_list_notify(&migration_state_notifiers, s);
 345 }
 346
 347 static void migrate_fd_cancel(MigrationState *s)
 348 {
 349     int old_state ;
 350     QEMUFile *f = migrate_get_current()->file;
 351     trace_migrate_fd_cancel();
 352
 353     do {
 354         old_state = s->state;
 355         if (old_state != MIG_STATE_SETUP && old_state != MIG_STATE_ACTIVE) {
 356             break;
 357         }
 358         migrate_set_state(s, old_state, MIG_STATE_CANCELLING);
 359     } while (s->state != MIG_STATE_CANCELLING);
 360
 361     /*
 362      * If we're unlucky the migration code might be stuck somewhere in a
 363      * send/write while the network has failed and is waiting to timeout;
 364      * if we've got shutdown(2) available then we can force it to quit.
 365      * The outgoing qemu file gets closed in migrate_fd_cleanup that is
 366      * called in a bh, so there is no race against this cancel.
 367      */
 368     if (s->state == MIG_STATE_CANCELLING && f) {
 369         qemu_file_shutdown(f);
 370     }
 371 }
 372
 373 void add_migration_state_change_notifier(Notifier *notify)
 374 {
 375     notifier_list_add(&migration_state_notifiers, notify);
 376 }
 377
 378 void remove_migration_state_change_notifier(Notifier *notify)
 379 {
 380     notifier_remove(notify);
 381 }
 382
 383 bool migration_in_setup(MigrationState *s)
 384 {
 385     return s->state == MIG_STATE_SETUP;
 386 }
 387
 388 bool migration_has_finished(MigrationState *s)
 389 {
 390     return s->state == MIG_STATE_COMPLETED;
 391 }
 392
 393 bool migration_has_failed(MigrationState *s)
 394 {
 395     return (s->state == MIG_STATE_CANCELLED ||
 396             s->state == MIG_STATE_ERROR);
 397 }
 398
 399 static MigrationState *migrate_init(const MigrationParams *params)
 400 {
 401     MigrationState *s = migrate_get_current();
 402     int64_t bandwidth_limit = s->bandwidth_limit;
 403     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 404     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 405
 406     memcpy(enabled_capabilities, s->enabled_capabilities,
 407            sizeof(enabled_capabilities));
 408
 409     memset(s, 0, sizeof(*s));
 410     s->params = *params;
 411     memcpy(s->enabled_capabilities, enabled_capabilities,
 412            sizeof(enabled_capabilities));
 413     s->xbzrle_cache_size = xbzrle_cache_size;
 414
 415     s->bandwidth_limit = bandwidth_limit;
 416     s->state = MIG_STATE_SETUP;
 417     trace_migrate_set_state(MIG_STATE_SETUP);
 418
 419     s->total_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 420     return s;
 421 }
 422
 423 static GSList *migration_blockers;
 424
 425 void migrate_add_blocker(Error *reason)
 426 {
 427     migration_blockers = g_slist_prepend(migration_blockers, reason);
 428 }
 429
 430 void migrate_del_blocker(Error *reason)
 431 {
 432     migration_blockers = g_slist_remove(migration_blockers, reason);
 433 }
 434
 435 void qmp_migrate_incoming(const char *uri, Error **errp)
 436 {
 437     Error *local_err = NULL;
 438
 439     if (!deferred_incoming) {
 440         error_setg(errp, "'-incoming defer' is required for migrate_incoming");
 441         return;
 442     }
 443
 444     qemu_start_incoming_migration(uri, &local_err);
 445
 446     if (local_err) {
 447         error_propagate(errp, local_err);
 448         return;
 449     }
 450
 451     deferred_incoming = false;
 452 }
 453
 454 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 455                  bool has_inc, bool inc, bool has_detach, bool detach,
 456                  Error **errp)
 457 {
 458     Error *local_err = NULL;
 459     MigrationState *s = migrate_get_current();
 460     MigrationParams params;
 461     const char *p;
 462
 463     params.blk = has_blk && blk;
 464     params.shared = has_inc && inc;
 465
 466     if (s->state == MIG_STATE_ACTIVE || s->state == MIG_STATE_SETUP ||
 467         s->state == MIG_STATE_CANCELLING) {
 468         error_set(errp, QERR_MIGRATION_ACTIVE);
 469         return;
 470     }
 471
 472     if (runstate_check(RUN_STATE_INMIGRATE)) {
 473         error_setg(errp, "Guest is waiting for an incoming migration");
 474         return;
 475     }
 476
 477     if (qemu_savevm_state_blocked(errp)) {
 478         return;
 479     }
 480
 481     if (migration_blockers) {
 482         *errp = error_copy(migration_blockers->data);
 483         return;
 484     }
 485
 486     s = migrate_init(&params);
 487
 488     if (strstart(uri, "tcp:", &p)) {
 489         tcp_start_outgoing_migration(s, p, &local_err);
 490 #ifdef CONFIG_RDMA
 491     } else if (strstart(uri, "rdma:", &p)) {
 492         rdma_start_outgoing_migration(s, p, &local_err);
 493 #endif
 494 #if !defined(WIN32)
 495     } else if (strstart(uri, "exec:", &p)) {
 496         exec_start_outgoing_migration(s, p, &local_err);
 497     } else if (strstart(uri, "unix:", &p)) {
 498         unix_start_outgoing_migration(s, p, &local_err);
 499     } else if (strstart(uri, "fd:", &p)) {
 500         fd_start_outgoing_migration(s, p, &local_err);
 501 #endif
 502     } else {
 503         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 504         s->state = MIG_STATE_ERROR;
 505         return;
 506     }
 507
 508     if (local_err) {
 509         migrate_fd_error(s);
 510         error_propagate(errp, local_err);
 511         return;
 512     }
 513 }
 514
 515 void qmp_migrate_cancel(Error **errp)
 516 {
 517     migrate_fd_cancel(migrate_get_current());
 518 }
 519
 520 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 521 {
 522     MigrationState *s = migrate_get_current();
 523     int64_t new_size;
 524
 525     /* Check for truncation */
 526     if (value != (size_t)value) {
 527         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 528                   "exceeding address space");
 529         return;
 530     }
 531
 532     /* Cache should not be larger than guest ram size */
 533     if (value > ram_bytes_total()) {
 534         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 535                   "exceeds guest ram size ");
 536         return;
 537     }
 538
 539     new_size = xbzrle_cache_resize(value);
 540     if (new_size < 0) {
 541         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 542                   "is smaller than page size");
 543         return;
 544     }
 545
 546     s->xbzrle_cache_size = new_size;
 547 }
 548
 549 int64_t qmp_query_migrate_cache_size(Error **errp)
 550 {
 551     return migrate_xbzrle_cache_size();
 552 }
 553
 554 void qmp_migrate_set_speed(int64_t value, Error **errp)
 555 {
 556     MigrationState *s;
 557
 558     if (value < 0) {
 559         value = 0;
 560     }
 561     if (value > SIZE_MAX) {
 562         value = SIZE_MAX;
 563     }
 564
 565     s = migrate_get_current();
 566     s->bandwidth_limit = value;
 567     if (s->file) {
 568         qemu_file_set_rate_limit(s->file, s->bandwidth_limit / XFER_LIMIT_RATIO);
 569     }
 570 }
 571
 572 void qmp_migrate_set_downtime(double value, Error **errp)
 573 {
 574     value *= 1e9;
 575     value = MAX(0, MIN(UINT64_MAX, value));
 576     max_downtime = (uint64_t)value;
 577 }
 578
 579 bool migrate_rdma_pin_all(void)
 580 {
 581     MigrationState *s;
 582
 583     s = migrate_get_current();
 584
 585     return s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL];
 586 }
 587
 588 bool migrate_auto_converge(void)
 589 {
 590     MigrationState *s;
 591
 592     s = migrate_get_current();
 593
 594     return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE];
 595 }
 596
 597 bool migrate_zero_blocks(void)
 598 {
 599     MigrationState *s;
 600
 601     s = migrate_get_current();
 602
 603     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 604 }
 605
 606 int migrate_use_xbzrle(void)
 607 {
 608     MigrationState *s;
 609
 610     s = migrate_get_current();
 611
 612     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 613 }
 614
 615 int64_t migrate_xbzrle_cache_size(void)
 616 {
 617     MigrationState *s;
 618
 619     s = migrate_get_current();
 620
 621     return s->xbzrle_cache_size;
 622 }
 623
 624 /* migration thread support */
 625
 626 static void *migration_thread(void *opaque)
 627 {
 628     MigrationState *s = opaque;
 629     int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 630     int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
 631     int64_t initial_bytes = 0;
 632     int64_t max_size = 0;
 633     int64_t start_time = initial_time;
 634     bool old_vm_running = false;
 635
 636     qemu_savevm_state_begin(s->file, &s->params);
 637
 638     s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
 639     migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE);
 640
 641     while (s->state == MIG_STATE_ACTIVE) {
 642         int64_t current_time;
 643         uint64_t pending_size;
 644
 645         if (!qemu_file_rate_limit(s->file)) {
 646             pending_size = qemu_savevm_state_pending(s->file, max_size);
 647             trace_migrate_pending(pending_size, max_size);
 648             if (pending_size && pending_size >= max_size) {
 649                 qemu_savevm_state_iterate(s->file);
 650             } else {
 651                 int ret;
 652
 653                 qemu_mutex_lock_iothread();
 654                 start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 655                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 656                 old_vm_running = runstate_is_running();
 657
 658                 ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 659                 if (ret >= 0) {
 660                     qemu_file_set_rate_limit(s->file, INT64_MAX);
 661                     qemu_savevm_state_complete(s->file);
 662                 }
 663                 qemu_mutex_unlock_iothread();
 664
 665                 if (ret < 0) {
 666                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 667                     break;
 668                 }
 669
 670                 if (!qemu_file_get_error(s->file)) {
 671                     migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_COMPLETED);
 672                     break;
 673                 }
 674             }
 675         }
 676
 677         if (qemu_file_get_error(s->file)) {
 678             migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR);
 679             break;
 680         }
 681         current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 682         if (current_time >= initial_time + BUFFER_DELAY) {
 683             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
 684             uint64_t time_spent = current_time - initial_time;
 685             double bandwidth = transferred_bytes / time_spent;
 686             max_size = bandwidth * migrate_max_downtime() / 1000000;
 687
 688             s->mbps = time_spent ? (((double) transferred_bytes * 8.0) /
 689                     ((double) time_spent / 1000.0)) / 1000.0 / 1000.0 : -1;
 690
 691             trace_migrate_transferred(transferred_bytes, time_spent,
 692                                       bandwidth, max_size);
 693             /* if we haven't sent anything, we don't want to recalculate
 694                10000 is a small enough number for our purposes */
 695             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 696                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 697             }
 698
 699             qemu_file_reset_rate_limit(s->file);
 700             initial_time = current_time;
 701             initial_bytes = qemu_ftell(s->file);
 702         }
 703         if (qemu_file_rate_limit(s->file)) {
 704             /* usleep expects microseconds */
 705             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 706         }
 707     }
 708
 709     qemu_mutex_lock_iothread();
 710     if (s->state == MIG_STATE_COMPLETED) {
 711         int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
 712         uint64_t transferred_bytes = qemu_ftell(s->file);
 713         s->total_time = end_time - s->total_time;
 714         s->downtime = end_time - start_time;
 715         if (s->total_time) {
 716             s->mbps = (((double) transferred_bytes * 8.0) /
 717                        ((double) s->total_time)) / 1000;
 718         }
 719         runstate_set(RUN_STATE_POSTMIGRATE);
 720     } else {
 721         if (old_vm_running) {
 722             vm_start();
 723         }
 724     }
 725     qemu_bh_schedule(s->cleanup_bh);
 726     qemu_mutex_unlock_iothread();
 727
 728     return NULL;
 729 }
 730
 731 void migrate_fd_connect(MigrationState *s)
 732 {
 733     s->state = MIG_STATE_SETUP;
 734     trace_migrate_set_state(MIG_STATE_SETUP);
 735
 736     /* This is a best 1st approximation. ns to ms */
 737     s->expected_downtime = max_downtime/1000000;
 738     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 739
 740     qemu_file_set_rate_limit(s->file,
 741                              s->bandwidth_limit / XFER_LIMIT_RATIO);
 742
 743     /* Notify before starting migration thread */
 744     notifier_list_notify(&migration_state_notifiers, s);
 745
 746     qemu_thread_create(&s->thread, "migration", migration_thread, s,
 747                        QEMU_THREAD_JOINABLE);
 748 }