We can migrate some dirty pages during the gap of checkpointing, by this way, we can reduce the amount of ram migrated during checkpointing.
Signed-off-by: Hailiang Zhang <zhang.zhanghaili...@huawei.com> --- migration/colo.c | 69 +++++++++++++++++++++++++++++++++++++++--- migration/migration.h | 1 + migration/trace-events | 1 + qapi/migration.json | 4 ++- 4 files changed, 70 insertions(+), 5 deletions(-) diff --git a/migration/colo.c b/migration/colo.c index 93c5a452fb..d30c6bc4ad 100644 --- a/migration/colo.c +++ b/migration/colo.c @@ -46,6 +46,13 @@ static COLOMode last_colo_mode; #define COLO_BUFFER_BASE_SIZE (4 * 1024 * 1024) +#define DEFAULT_RAM_PENDING_CHECK 1000 + +/* should be calculated by bandwidth and max downtime ? */ +#define THRESHOLD_PENDING_SIZE (100 * 1024 * 1024UL) + +static int checkpoint_request; + bool migration_in_colo_state(void) { MigrationState *s = migrate_get_current(); @@ -516,6 +523,20 @@ static void colo_compare_notify_checkpoint(Notifier *notifier, void *data) colo_checkpoint_notify(data); } +static bool colo_need_migrate_ram_background(MigrationState *s) +{ + uint64_t pending_size, pend_pre, pend_compat, pend_post; + int64_t max_size = THRESHOLD_PENDING_SIZE; + + qemu_savevm_state_pending(s->to_dst_file, max_size, &pend_pre, + &pend_compat, &pend_post); + pending_size = pend_pre + pend_compat + pend_post; + + trace_colo_need_migrate_ram_background(pending_size); + return (pending_size >= max_size); +} + + static void colo_process_checkpoint(MigrationState *s) { QIOChannelBuffer *bioc; @@ -571,6 +592,8 @@ static void colo_process_checkpoint(MigrationState *s) timer_mod(s->colo_delay_timer, current_time + s->parameters.x_checkpoint_delay); + timer_mod(s->pending_ram_check_timer, + current_time + DEFAULT_RAM_PENDING_CHECK); while (s->state == MIGRATION_STATUS_COLO) { if (failover_get_state() != FAILOVER_STATUS_NONE) { @@ -583,10 +606,25 @@ static void colo_process_checkpoint(MigrationState *s) if (s->state != MIGRATION_STATUS_COLO) { goto out; } - ret = colo_do_checkpoint_transaction(s, bioc, fb); - if (ret < 0) { - goto out; - } + if (atomic_xchg(&checkpoint_request, 0)) { + /* start a colo checkpoint */ + ret = colo_do_checkpoint_transaction(s, bioc, fb); + if (ret < 0) { + goto out; + } + } else { + if (colo_need_migrate_ram_background(s)) { + colo_send_message(s->to_dst_file, + COLO_MESSAGE_MIGRATE_RAM_BACKGROUND, + &local_err); + if (local_err) { + goto out; + } + + qemu_savevm_state_iterate(s->to_dst_file, false); + qemu_put_byte(s->to_dst_file, QEMU_VM_EOF); + } + } } out: @@ -626,6 +664,8 @@ out: colo_compare_unregister_notifier(&packets_compare_notifier); timer_del(s->colo_delay_timer); timer_free(s->colo_delay_timer); + timer_del(s->pending_ram_check_timer); + timer_free(s->pending_ram_check_timer); qemu_sem_destroy(&s->colo_checkpoint_sem); /* @@ -643,6 +683,7 @@ void colo_checkpoint_notify(void *opaque) MigrationState *s = opaque; int64_t next_notify_time; + atomic_inc(&checkpoint_request); qemu_sem_post(&s->colo_checkpoint_sem); s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST); next_notify_time = s->colo_checkpoint_time + @@ -650,6 +691,19 @@ void colo_checkpoint_notify(void *opaque) timer_mod(s->colo_delay_timer, next_notify_time); } +static void colo_pending_ram_check_notify(void *opaque) +{ + int64_t next_notify_time; + MigrationState *s = opaque; + + if (migration_in_colo_state()) { + next_notify_time = DEFAULT_RAM_PENDING_CHECK + + qemu_clock_get_ms(QEMU_CLOCK_HOST); + timer_mod(s->pending_ram_check_timer, next_notify_time); + qemu_sem_post(&s->colo_checkpoint_sem); + } +} + void migrate_start_colo_process(MigrationState *s) { qemu_mutex_unlock_iothread(); @@ -657,6 +711,8 @@ void migrate_start_colo_process(MigrationState *s) s->colo_delay_timer = timer_new_ms(QEMU_CLOCK_HOST, colo_checkpoint_notify, s); + s->pending_ram_check_timer = timer_new_ms(QEMU_CLOCK_HOST, + colo_pending_ram_check_notify, s); qemu_sem_init(&s->colo_exit_sem, 0); migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_COLO); @@ -805,6 +861,11 @@ static void colo_wait_handle_message(MigrationIncomingState *mis, case COLO_MESSAGE_CHECKPOINT_REQUEST: colo_incoming_process_checkpoint(mis, fb, bioc, errp); break; + case COLO_MESSAGE_MIGRATE_RAM_BACKGROUND: + if (qemu_loadvm_state_main(mis->from_src_file, mis) < 0) { + error_setg(errp, "Load ram background failed"); + } + break; default: error_setg(errp, "Got unknown COLO message: %d", msg); break; diff --git a/migration/migration.h b/migration/migration.h index 8473ddfc88..5355259789 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -219,6 +219,7 @@ struct MigrationState QemuSemaphore colo_checkpoint_sem; int64_t colo_checkpoint_time; QEMUTimer *colo_delay_timer; + QEMUTimer *pending_ram_check_timer; /* The first error that has occurred. We used the mutex to be able to return the 1st error message */ diff --git a/migration/trace-events b/migration/trace-events index 4ab0a503d2..f2ed0c8645 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -295,6 +295,7 @@ migration_tls_incoming_handshake_complete(void) "" colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'" colo_send_message(const char *msg) "Send '%s' message" colo_receive_message(const char *msg) "Receive '%s' message" +colo_need_migrate_ram_background(uint64_t pending_size) "Pending 0x%" PRIx64 " dirty ram" # colo-failover.c colo_failover_set_state(const char *new_state) "new state %s" diff --git a/qapi/migration.json b/qapi/migration.json index b7348d0c8b..ff7a4f18b0 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -977,12 +977,14 @@ # # @vmstate-loaded: VM's state has been loaded by SVM. # +# @migrate-ram-background: Send some dirty pages during the gap of COLO checkpoint +# # Since: 2.8 ## { 'enum': 'COLOMessage', 'data': [ 'checkpoint-ready', 'checkpoint-request', 'checkpoint-reply', 'vmstate-send', 'vmstate-size', 'vmstate-received', - 'vmstate-loaded' ] } + 'vmstate-loaded', 'migrate-ram-background' ] } ## # @COLOMode: -- 2.21.0