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