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 "migration/migration.h"
  18 #include "monitor/monitor.h"
  19 #include "migration/qemu-file.h"
  20 #include "sysemu/sysemu.h"
  21 #include "block/block.h"
  22 #include "qemu/sockets.h"
  23 #include "migration/block.h"
  24 #include "qemu/thread.h"
  25 #include "qmp-commands.h"
  26 #include "trace.h"
  27
  28 //#define DEBUG_MIGRATION
  29
  30 #ifdef DEBUG_MIGRATION
  31 #define DPRINTF(fmt, ...) \
  32     do { printf("migration: " fmt, ## __VA_ARGS__); } while (0)
  33 #else
  34 #define DPRINTF(fmt, ...) \
  35     do { } while (0)
  36 #endif
  37
  38 enum {
  39     MIG_STATE_ERROR,
  40     MIG_STATE_SETUP,
  41     MIG_STATE_CANCELLED,
  42     MIG_STATE_ACTIVE,
  43     MIG_STATE_COMPLETED,
  44 };
  45
  46 #define MAX_THROTTLE  (32 << 20)      /* Migration speed throttling */
  47
  48 /* Amount of time to allocate to each "chunk" of bandwidth-throttled
  49  * data. */
  50 #define BUFFER_DELAY     100
  51 #define XFER_LIMIT_RATIO (1000 / BUFFER_DELAY)
  52
  53 /* Migration XBZRLE default cache size */
  54 #define DEFAULT_MIGRATE_CACHE_SIZE (64 * 1024 * 1024)
  55
  56 static NotifierList migration_state_notifiers =
  57     NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
  58
  59 /* When we add fault tolerance, we could have several
  60    migrations at once.  For now we don't need to add
  61    dynamic creation of migration */
  62
  63 MigrationState *migrate_get_current(void)
  64 {
  65     static MigrationState current_migration = {
  66         .state = MIG_STATE_SETUP,
  67         .bandwidth_limit = MAX_THROTTLE,
  68         .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
  69     };
  70
  71     return &current_migration;
  72 }
  73
  74 void qemu_start_incoming_migration(const char *uri, Error **errp)
  75 {
  76     const char *p;
  77
  78     if (strstart(uri, "tcp:", &p))
  79         tcp_start_incoming_migration(p, errp);
  80 #if !defined(WIN32)
  81     else if (strstart(uri, "exec:", &p))
  82         exec_start_incoming_migration(p, errp);
  83     else if (strstart(uri, "unix:", &p))
  84         unix_start_incoming_migration(p, errp);
  85     else if (strstart(uri, "fd:", &p))
  86         fd_start_incoming_migration(p, errp);
  87 #endif
  88     else {
  89         error_setg(errp, "unknown migration protocol: %s", uri);
  90     }
  91 }
  92
  93 static void process_incoming_migration_co(void *opaque)
  94 {
  95     QEMUFile *f = opaque;
  96     int ret;
  97
  98     ret = qemu_loadvm_state(f);
  99     qemu_fclose(f);
 100     if (ret < 0) {
 101         fprintf(stderr, "load of migration failed\n");
 102         exit(0);
 103     }
 104     qemu_announce_self();
 105     DPRINTF("successfully loaded vm state\n");
 106
 107     bdrv_clear_incoming_migration_all();
 108     /* Make sure all file formats flush their mutable metadata */
 109     bdrv_invalidate_cache_all();
 110
 111     if (autostart) {
 112         vm_start();
 113     } else {
 114         runstate_set(RUN_STATE_PAUSED);
 115     }
 116 }
 117
 118 void process_incoming_migration(QEMUFile *f)
 119 {
 120     Coroutine *co = qemu_coroutine_create(process_incoming_migration_co);
 121     int fd = qemu_get_fd(f);
 122
 123     assert(fd != -1);
 124     socket_set_nonblock(fd);
 125     qemu_coroutine_enter(co, f);
 126 }
 127
 128 /* amount of nanoseconds we are willing to wait for migration to be down.
 129  * the choice of nanoseconds is because it is the maximum resolution that
 130  * get_clock() can achieve. It is an internal measure. All user-visible
 131  * units must be in seconds */
 132 static uint64_t max_downtime = 30000000;
 133
 134 uint64_t migrate_max_downtime(void)
 135 {
 136     return max_downtime;
 137 }
 138
 139 MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 140 {
 141     MigrationCapabilityStatusList *head = NULL;
 142     MigrationCapabilityStatusList *caps;
 143     MigrationState *s = migrate_get_current();
 144     int i;
 145
 146     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
 147         if (head == NULL) {
 148             head = g_malloc0(sizeof(*caps));
 149             caps = head;
 150         } else {
 151             caps->next = g_malloc0(sizeof(*caps));
 152             caps = caps->next;
 153         }
 154         caps->value =
 155             g_malloc(sizeof(*caps->value));
 156         caps->value->capability = i;
 157         caps->value->state = s->enabled_capabilities[i];
 158     }
 159
 160     return head;
 161 }
 162
 163 static void get_xbzrle_cache_stats(MigrationInfo *info)
 164 {
 165     if (migrate_use_xbzrle()) {
 166         info->has_xbzrle_cache = true;
 167         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
 168         info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
 169         info->xbzrle_cache->bytes = xbzrle_mig_bytes_transferred();
 170         info->xbzrle_cache->pages = xbzrle_mig_pages_transferred();
 171         info->xbzrle_cache->cache_miss = xbzrle_mig_pages_cache_miss();
 172         info->xbzrle_cache->overflow = xbzrle_mig_pages_overflow();
 173     }
 174 }
 175
 176 MigrationInfo *qmp_query_migrate(Error **errp)
 177 {
 178     MigrationInfo *info = g_malloc0(sizeof(*info));
 179     MigrationState *s = migrate_get_current();
 180
 181     switch (s->state) {
 182     case MIG_STATE_SETUP:
 183         /* no migration has happened ever */
 184         break;
 185     case MIG_STATE_ACTIVE:
 186         info->has_status = true;
 187         info->status = g_strdup("active");
 188         info->has_total_time = true;
 189         info->total_time = qemu_get_clock_ms(rt_clock)
 190             - s->total_time;
 191         info->has_expected_downtime = true;
 192         info->expected_downtime = s->expected_downtime;
 193
 194         info->has_ram = true;
 195         info->ram = g_malloc0(sizeof(*info->ram));
 196         info->ram->transferred = ram_bytes_transferred();
 197         info->ram->remaining = ram_bytes_remaining();
 198         info->ram->total = ram_bytes_total();
 199         info->ram->duplicate = dup_mig_pages_transferred();
 200         info->ram->normal = norm_mig_pages_transferred();
 201         info->ram->normal_bytes = norm_mig_bytes_transferred();
 202         info->ram->dirty_pages_rate = s->dirty_pages_rate;
 203
 204
 205         if (blk_mig_active()) {
 206             info->has_disk = true;
 207             info->disk = g_malloc0(sizeof(*info->disk));
 208             info->disk->transferred = blk_mig_bytes_transferred();
 209             info->disk->remaining = blk_mig_bytes_remaining();
 210             info->disk->total = blk_mig_bytes_total();
 211         }
 212
 213         get_xbzrle_cache_stats(info);
 214         break;
 215     case MIG_STATE_COMPLETED:
 216         get_xbzrle_cache_stats(info);
 217
 218         info->has_status = true;
 219         info->status = g_strdup("completed");
 220         info->total_time = s->total_time;
 221         info->has_downtime = true;
 222         info->downtime = s->downtime;
 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 = 0;
 228         info->ram->total = ram_bytes_total();
 229         info->ram->duplicate = dup_mig_pages_transferred();
 230         info->ram->normal = norm_mig_pages_transferred();
 231         info->ram->normal_bytes = norm_mig_bytes_transferred();
 232         break;
 233     case MIG_STATE_ERROR:
 234         info->has_status = true;
 235         info->status = g_strdup("failed");
 236         break;
 237     case MIG_STATE_CANCELLED:
 238         info->has_status = true;
 239         info->status = g_strdup("cancelled");
 240         break;
 241     }
 242
 243     return info;
 244 }
 245
 246 void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
 247                                   Error **errp)
 248 {
 249     MigrationState *s = migrate_get_current();
 250     MigrationCapabilityStatusList *cap;
 251
 252     if (s->state == MIG_STATE_ACTIVE) {
 253         error_set(errp, QERR_MIGRATION_ACTIVE);
 254         return;
 255     }
 256
 257     for (cap = params; cap; cap = cap->next) {
 258         s->enabled_capabilities[cap->value->capability] = cap->value->state;
 259     }
 260 }
 261
 262 /* shared migration helpers */
 263
 264 static void migrate_fd_cleanup(void *opaque)
 265 {
 266     MigrationState *s = opaque;
 267
 268     qemu_bh_delete(s->cleanup_bh);
 269     s->cleanup_bh = NULL;
 270
 271     if (s->file) {
 272         DPRINTF("closing file\n");
 273         qemu_fclose(s->file);
 274         s->file = NULL;
 275     }
 276
 277     assert(s->fd == -1);
 278     assert(s->state != MIG_STATE_ACTIVE);
 279
 280     if (s->state != MIG_STATE_COMPLETED) {
 281         qemu_savevm_state_cancel();
 282     }
 283
 284     notifier_list_notify(&migration_state_notifiers, s);
 285 }
 286
 287 static void migrate_finish_set_state(MigrationState *s, int new_state)
 288 {
 289     if (__sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE,
 290                                     new_state) == new_state) {
 291         trace_migrate_set_state(new_state);
 292     }
 293 }
 294
 295 void migrate_fd_error(MigrationState *s)
 296 {
 297     DPRINTF("setting error state\n");
 298     assert(s->file == NULL);
 299     s->state = MIG_STATE_ERROR;
 300     trace_migrate_set_state(MIG_STATE_ERROR);
 301     notifier_list_notify(&migration_state_notifiers, s);
 302 }
 303
 304 static ssize_t migrate_fd_put_buffer(MigrationState *s, const void *data,
 305                                      size_t size)
 306 {
 307     ssize_t ret;
 308
 309     if (s->state != MIG_STATE_ACTIVE) {
 310         return -EIO;
 311     }
 312
 313     do {
 314         ret = s->write(s, data, size);
 315     } while (ret == -1 && ((s->get_error(s)) == EINTR));
 316
 317     if (ret == -1)
 318         ret = -(s->get_error(s));
 319
 320     return ret;
 321 }
 322
 323 static void migrate_fd_cancel(MigrationState *s)
 324 {
 325     DPRINTF("cancelling migration\n");
 326
 327     migrate_finish_set_state(s, MIG_STATE_CANCELLED);
 328 }
 329
 330 int migrate_fd_close(MigrationState *s)
 331 {
 332     int rc = 0;
 333     if (s->fd != -1) {
 334         rc = s->close(s);
 335         s->fd = -1;
 336     }
 337     return rc;
 338 }
 339
 340 void add_migration_state_change_notifier(Notifier *notify)
 341 {
 342     notifier_list_add(&migration_state_notifiers, notify);
 343 }
 344
 345 void remove_migration_state_change_notifier(Notifier *notify)
 346 {
 347     notifier_remove(notify);
 348 }
 349
 350 bool migration_is_active(MigrationState *s)
 351 {
 352     return s->state == MIG_STATE_ACTIVE;
 353 }
 354
 355 bool migration_has_finished(MigrationState *s)
 356 {
 357     return s->state == MIG_STATE_COMPLETED;
 358 }
 359
 360 bool migration_has_failed(MigrationState *s)
 361 {
 362     return (s->state == MIG_STATE_CANCELLED ||
 363             s->state == MIG_STATE_ERROR);
 364 }
 365
 366 static MigrationState *migrate_init(const MigrationParams *params)
 367 {
 368     MigrationState *s = migrate_get_current();
 369     int64_t bandwidth_limit = s->bandwidth_limit;
 370     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 371     int64_t xbzrle_cache_size = s->xbzrle_cache_size;
 372
 373     memcpy(enabled_capabilities, s->enabled_capabilities,
 374            sizeof(enabled_capabilities));
 375
 376     memset(s, 0, sizeof(*s));
 377     s->bandwidth_limit = bandwidth_limit;
 378     s->params = *params;
 379     memcpy(s->enabled_capabilities, enabled_capabilities,
 380            sizeof(enabled_capabilities));
 381     s->xbzrle_cache_size = xbzrle_cache_size;
 382
 383     s->bandwidth_limit = bandwidth_limit;
 384     s->state = MIG_STATE_SETUP;
 385     trace_migrate_set_state(MIG_STATE_SETUP);
 386
 387     s->total_time = qemu_get_clock_ms(rt_clock);
 388     return s;
 389 }
 390
 391 static GSList *migration_blockers;
 392
 393 void migrate_add_blocker(Error *reason)
 394 {
 395     migration_blockers = g_slist_prepend(migration_blockers, reason);
 396 }
 397
 398 void migrate_del_blocker(Error *reason)
 399 {
 400     migration_blockers = g_slist_remove(migration_blockers, reason);
 401 }
 402
 403 void qmp_migrate(const char *uri, bool has_blk, bool blk,
 404                  bool has_inc, bool inc, bool has_detach, bool detach,
 405                  Error **errp)
 406 {
 407     Error *local_err = NULL;
 408     MigrationState *s = migrate_get_current();
 409     MigrationParams params;
 410     const char *p;
 411
 412     params.blk = blk;
 413     params.shared = inc;
 414
 415     if (s->state == MIG_STATE_ACTIVE) {
 416         error_set(errp, QERR_MIGRATION_ACTIVE);
 417         return;
 418     }
 419
 420     if (qemu_savevm_state_blocked(errp)) {
 421         return;
 422     }
 423
 424     if (migration_blockers) {
 425         *errp = error_copy(migration_blockers->data);
 426         return;
 427     }
 428
 429     s = migrate_init(&params);
 430
 431     if (strstart(uri, "tcp:", &p)) {
 432         tcp_start_outgoing_migration(s, p, &local_err);
 433 #if !defined(WIN32)
 434     } else if (strstart(uri, "exec:", &p)) {
 435         exec_start_outgoing_migration(s, p, &local_err);
 436     } else if (strstart(uri, "unix:", &p)) {
 437         unix_start_outgoing_migration(s, p, &local_err);
 438     } else if (strstart(uri, "fd:", &p)) {
 439         fd_start_outgoing_migration(s, p, &local_err);
 440 #endif
 441     } else {
 442         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "uri", "a valid migration protocol");
 443         return;
 444     }
 445
 446     if (local_err) {
 447         migrate_fd_error(s);
 448         error_propagate(errp, local_err);
 449         return;
 450     }
 451 }
 452
 453 void qmp_migrate_cancel(Error **errp)
 454 {
 455     migrate_fd_cancel(migrate_get_current());
 456 }
 457
 458 void qmp_migrate_set_cache_size(int64_t value, Error **errp)
 459 {
 460     MigrationState *s = migrate_get_current();
 461
 462     /* Check for truncation */
 463     if (value != (size_t)value) {
 464         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
 465                   "exceeding address space");
 466         return;
 467     }
 468
 469     s->xbzrle_cache_size = xbzrle_cache_resize(value);
 470 }
 471
 472 int64_t qmp_query_migrate_cache_size(Error **errp)
 473 {
 474     return migrate_xbzrle_cache_size();
 475 }
 476
 477 void qmp_migrate_set_speed(int64_t value, Error **errp)
 478 {
 479     MigrationState *s;
 480
 481     if (value < 0) {
 482         value = 0;
 483     }
 484
 485     s = migrate_get_current();
 486     s->bandwidth_limit = value;
 487     qemu_file_set_rate_limit(s->file, s->bandwidth_limit);
 488 }
 489
 490 void qmp_migrate_set_downtime(double value, Error **errp)
 491 {
 492     value *= 1e9;
 493     value = MAX(0, MIN(UINT64_MAX, value));
 494     max_downtime = (uint64_t)value;
 495 }
 496
 497 int migrate_use_xbzrle(void)
 498 {
 499     MigrationState *s;
 500
 501     s = migrate_get_current();
 502
 503     return s->enabled_capabilities[MIGRATION_CAPABILITY_XBZRLE];
 504 }
 505
 506 int64_t migrate_xbzrle_cache_size(void)
 507 {
 508     MigrationState *s;
 509
 510     s = migrate_get_current();
 511
 512     return s->xbzrle_cache_size;
 513 }
 514
 515 /* migration thread support */
 516
 517 static int migration_put_buffer(void *opaque, const uint8_t *buf,
 518                                int64_t pos, int size)
 519 {
 520     MigrationState *s = opaque;
 521     ssize_t ret;
 522     size_t sent;
 523
 524     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
 525
 526     ret = qemu_file_get_error(s->file);
 527     if (ret) {
 528         DPRINTF("flush when error, bailing: %s\n", strerror(-ret));
 529         return ret;
 530     }
 531
 532     if (size <= 0) {
 533         return size;
 534     }
 535
 536     sent = 0;
 537     while (size) {
 538         ret = migrate_fd_put_buffer(s, buf, size);
 539         if (ret <= 0) {
 540             DPRINTF("error flushing data, %zd\n", ret);
 541             return ret;
 542         } else {
 543             DPRINTF("flushed %zd byte(s)\n", ret);
 544             sent += ret;
 545             buf += ret;
 546             size -= ret;
 547             s->bytes_xfer += ret;
 548         }
 549     }
 550
 551     return sent;
 552 }
 553
 554 static int migration_close(void *opaque)
 555 {
 556     MigrationState *s = opaque;
 557
 558     DPRINTF("closing\n");
 559
 560     qemu_mutex_unlock_iothread();
 561     qemu_thread_join(&s->thread);
 562     qemu_mutex_lock_iothread();
 563     assert(s->state != MIG_STATE_ACTIVE);
 564
 565     return migrate_fd_close(s);
 566 }
 567
 568 static int migration_get_fd(void *opaque)
 569 {
 570     MigrationState *s = opaque;
 571
 572     return s->fd;
 573 }
 574
 575 /*
 576  * The meaning of the return values is:
 577  *   0: We can continue sending
 578  *   1: Time to stop
 579  *   negative: There has been an error
 580  */
 581 static int migration_rate_limit(void *opaque)
 582 {
 583     MigrationState *s = opaque;
 584     int ret;
 585
 586     ret = qemu_file_get_error(s->file);
 587     if (ret) {
 588         return ret;
 589     }
 590
 591     if (s->bytes_xfer >= s->xfer_limit) {
 592         return 1;
 593     }
 594
 595     return 0;
 596 }
 597
 598 static int64_t migration_set_rate_limit(void *opaque, int64_t new_rate)
 599 {
 600     MigrationState *s = opaque;
 601     if (qemu_file_get_error(s->file)) {
 602         goto out;
 603     }
 604     if (new_rate > SIZE_MAX) {
 605         new_rate = SIZE_MAX;
 606     }
 607
 608     s->xfer_limit = new_rate / XFER_LIMIT_RATIO;
 609
 610 out:
 611     return s->xfer_limit;
 612 }
 613
 614 static int64_t migration_get_rate_limit(void *opaque)
 615 {
 616     MigrationState *s = opaque;
 617
 618     return s->xfer_limit;
 619 }
 620
 621 static void *migration_thread(void *opaque)
 622 {
 623     MigrationState *s = opaque;
 624     int64_t initial_time = qemu_get_clock_ms(rt_clock);
 625     int64_t sleep_time = 0;
 626     int64_t max_size = 0;
 627     int64_t start_time = initial_time;
 628     bool old_vm_running = false;
 629     bool last_round = false;
 630
 631     DPRINTF("beginning savevm\n");
 632     qemu_savevm_state_begin(s->file, &s->params);
 633
 634     while (s->state == MIG_STATE_ACTIVE) {
 635         int64_t current_time;
 636         uint64_t pending_size;
 637
 638         if (s->bytes_xfer < s->xfer_limit) {
 639             DPRINTF("iterate\n");
 640             pending_size = qemu_savevm_state_pending(s->file, max_size);
 641             DPRINTF("pending size %lu max %lu\n", pending_size, max_size);
 642             if (pending_size && pending_size >= max_size) {
 643                 qemu_savevm_state_iterate(s->file);
 644             } else {
 645                 DPRINTF("done iterating\n");
 646                 qemu_mutex_lock_iothread();
 647                 start_time = qemu_get_clock_ms(rt_clock);
 648                 qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
 649                 old_vm_running = runstate_is_running();
 650                 vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
 651                 s->xfer_limit = INT_MAX;
 652                 qemu_savevm_state_complete(s->file);
 653                 last_round = true;
 654                 qemu_mutex_unlock_iothread();
 655             }
 656         }
 657
 658         current_time = qemu_get_clock_ms(rt_clock);
 659         if (current_time >= initial_time + BUFFER_DELAY) {
 660             uint64_t transferred_bytes = s->bytes_xfer;
 661             uint64_t time_spent = current_time - initial_time - sleep_time;
 662             double bandwidth = transferred_bytes / time_spent;
 663             max_size = bandwidth * migrate_max_downtime() / 1000000;
 664
 665             DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64
 666                     " bandwidth %g max_size %" PRId64 "\n",
 667                     transferred_bytes, time_spent, bandwidth, max_size);
 668             /* if we haven't sent anything, we don't want to recalculate
 669                10000 is a small enough number for our purposes */
 670             if (s->dirty_bytes_rate && transferred_bytes > 10000) {
 671                 s->expected_downtime = s->dirty_bytes_rate / bandwidth;
 672             }
 673
 674             s->bytes_xfer = 0;
 675             sleep_time = 0;
 676             initial_time = current_time;
 677         }
 678         if (!last_round && (s->bytes_xfer >= s->xfer_limit)) {
 679             /* usleep expects microseconds */
 680             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
 681             sleep_time += qemu_get_clock_ms(rt_clock) - current_time;
 682         }
 683         if (qemu_file_get_error(s->file)) {
 684             migrate_finish_set_state(s, MIG_STATE_ERROR);
 685         } else if (last_round) {
 686             migrate_finish_set_state(s, MIG_STATE_COMPLETED);
 687         }
 688     }
 689
 690     qemu_mutex_lock_iothread();
 691     if (s->state == MIG_STATE_COMPLETED) {
 692         int64_t end_time = qemu_get_clock_ms(rt_clock);
 693         s->total_time = end_time - s->total_time;
 694         s->downtime = end_time - start_time;
 695         runstate_set(RUN_STATE_POSTMIGRATE);
 696     } else {
 697         if (old_vm_running) {
 698             assert(last_round);
 699             vm_start();
 700         }
 701     }
 702     qemu_bh_schedule(s->cleanup_bh);
 703     qemu_mutex_unlock_iothread();
 704
 705     return NULL;
 706 }
 707
 708 static const QEMUFileOps migration_file_ops = {
 709     .get_fd =         migration_get_fd,
 710     .put_buffer =     migration_put_buffer,
 711     .close =          migration_close,
 712     .rate_limit =     migration_rate_limit,
 713     .get_rate_limit = migration_get_rate_limit,
 714     .set_rate_limit = migration_set_rate_limit,
 715 };
 716
 717 void migrate_fd_connect(MigrationState *s)
 718 {
 719     s->state = MIG_STATE_ACTIVE;
 720     trace_migrate_set_state(MIG_STATE_ACTIVE);
 721
 722     s->bytes_xfer = 0;
 723     /* This is a best 1st approximation. ns to ms */
 724     s->expected_downtime = max_downtime/1000000;
 725
 726     s->xfer_limit = s->bandwidth_limit / XFER_LIMIT_RATIO;
 727
 728     s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup, s);
 729     s->file = qemu_fopen_ops(s, &migration_file_ops);
 730
 731     qemu_thread_create(&s->thread, migration_thread, s,
 732                        QEMU_THREAD_JOINABLE);
 733     notifier_list_notify(&migration_state_notifiers, s);
 734 }