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authorDr. David Alan Gilbert <dgilbert@redhat.com>2015-11-05 18:11:05 +0000
committerJuan Quintela <quintela@redhat.com>2015-11-10 15:00:27 +0100
commit1d34e4bf6a34f12b9ca387301b863b59f14d38ed (patch)
tree95830f4a2c1ea79975fd6f201b7f392f0c517d8c /migration
parentf0a227ade4b0331c9e12fc01f8b74e2531fd496d (diff)
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Postcopy: Postcopy startup in migration thread
Rework the migration thread to setup and start postcopy. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r--migration/migration.c174
1 files changed, 167 insertions, 7 deletions
diff --git a/migration/migration.c b/migration/migration.c
index afc863a..064986b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -745,7 +745,10 @@ static void migrate_fd_cleanup(void *opaque)
if (s->file) {
trace_migrate_fd_cleanup();
qemu_mutex_unlock_iothread();
- qemu_thread_join(&s->thread);
+ if (s->migration_thread_running) {
+ qemu_thread_join(&s->thread);
+ s->migration_thread_running = false;
+ }
qemu_mutex_lock_iothread();
migrate_compress_threads_join();
@@ -1238,7 +1241,6 @@ out:
return NULL;
}
-__attribute__ (( unused )) /* Until later in patch series */
static int open_return_path_on_source(MigrationState *ms)
{
@@ -1279,6 +1281,109 @@ static int await_return_path_close_on_source(MigrationState *ms)
return ms->rp_state.error;
}
+/*
+ * Switch from normal iteration to postcopy
+ * Returns non-0 on error
+ */
+static int postcopy_start(MigrationState *ms, bool *old_vm_running)
+{
+ int ret;
+ const QEMUSizedBuffer *qsb;
+ int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+ migrate_set_state(ms, MIGRATION_STATUS_ACTIVE,
+ MIGRATION_STATUS_POSTCOPY_ACTIVE);
+
+ trace_postcopy_start();
+ qemu_mutex_lock_iothread();
+ trace_postcopy_start_set_run();
+
+ qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
+ *old_vm_running = runstate_is_running();
+ global_state_store();
+ ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
+
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /*
+ * in Finish migrate and with the io-lock held everything should
+ * be quiet, but we've potentially still got dirty pages and we
+ * need to tell the destination to throw any pages it's already received
+ * that are dirty
+ */
+ if (ram_postcopy_send_discard_bitmap(ms)) {
+ error_report("postcopy send discard bitmap failed");
+ goto fail;
+ }
+
+ /*
+ * send rest of state - note things that are doing postcopy
+ * will notice we're in POSTCOPY_ACTIVE and not actually
+ * wrap their state up here
+ */
+ qemu_file_set_rate_limit(ms->file, INT64_MAX);
+ /* Ping just for debugging, helps line traces up */
+ qemu_savevm_send_ping(ms->file, 2);
+
+ /*
+ * While loading the device state we may trigger page transfer
+ * requests and the fd must be free to process those, and thus
+ * the destination must read the whole device state off the fd before
+ * it starts processing it. Unfortunately the ad-hoc migration format
+ * doesn't allow the destination to know the size to read without fully
+ * parsing it through each devices load-state code (especially the open
+ * coded devices that use get/put).
+ * So we wrap the device state up in a package with a length at the start;
+ * to do this we use a qemu_buf to hold the whole of the device state.
+ */
+ QEMUFile *fb = qemu_bufopen("w", NULL);
+ if (!fb) {
+ error_report("Failed to create buffered file");
+ goto fail;
+ }
+
+ qemu_savevm_state_complete_precopy(fb);
+ qemu_savevm_send_ping(fb, 3);
+
+ qemu_savevm_send_postcopy_run(fb);
+
+ /* <><> end of stuff going into the package */
+ qsb = qemu_buf_get(fb);
+
+ /* Now send that blob */
+ if (qemu_savevm_send_packaged(ms->file, qsb)) {
+ goto fail_closefb;
+ }
+ qemu_fclose(fb);
+ ms->downtime = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - time_at_stop;
+
+ qemu_mutex_unlock_iothread();
+
+ /*
+ * Although this ping is just for debug, it could potentially be
+ * used for getting a better measurement of downtime at the source.
+ */
+ qemu_savevm_send_ping(ms->file, 4);
+
+ ret = qemu_file_get_error(ms->file);
+ if (ret) {
+ error_report("postcopy_start: Migration stream errored");
+ migrate_set_state(ms, MIGRATION_STATUS_POSTCOPY_ACTIVE,
+ MIGRATION_STATUS_FAILED);
+ }
+
+ return ret;
+
+fail_closefb:
+ qemu_fclose(fb);
+fail:
+ migrate_set_state(ms, MIGRATION_STATUS_POSTCOPY_ACTIVE,
+ MIGRATION_STATUS_FAILED);
+ qemu_mutex_unlock_iothread();
+ return -1;
+}
+
/**
* migration_completion: Used by migration_thread when there's not much left.
* The caller 'breaks' the loop when this returns.
@@ -1332,6 +1437,7 @@ fail:
static void *migration_thread(void *opaque)
{
MigrationState *s = opaque;
+ /* Used by the bandwidth calcs, updated later */
int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
int64_t initial_bytes = 0;
@@ -1339,13 +1445,33 @@ static void *migration_thread(void *opaque)
int64_t start_time = initial_time;
int64_t end_time;
bool old_vm_running = false;
+ bool entered_postcopy = false;
+ /* The active state we expect to be in; ACTIVE or POSTCOPY_ACTIVE */
+ enum MigrationStatus current_active_state = MIGRATION_STATUS_ACTIVE;
rcu_register_thread();
qemu_savevm_state_header(s->file);
+
+ if (migrate_postcopy_ram()) {
+ /* Now tell the dest that it should open its end so it can reply */
+ qemu_savevm_send_open_return_path(s->file);
+
+ /* And do a ping that will make stuff easier to debug */
+ qemu_savevm_send_ping(s->file, 1);
+
+ /*
+ * Tell the destination that we *might* want to do postcopy later;
+ * if the other end can't do postcopy it should fail now, nice and
+ * early.
+ */
+ qemu_savevm_send_postcopy_advise(s->file);
+ }
+
qemu_savevm_state_begin(s->file, &s->params);
s->setup_time = qemu_clock_get_ms(QEMU_CLOCK_HOST) - setup_start;
+ current_active_state = MIGRATION_STATUS_ACTIVE;
migrate_set_state(s, MIGRATION_STATUS_SETUP, MIGRATION_STATUS_ACTIVE);
trace_migration_thread_setup_complete();
@@ -1364,18 +1490,34 @@ static void *migration_thread(void *opaque)
trace_migrate_pending(pending_size, max_size,
pend_post, pend_nonpost);
if (pending_size && pending_size >= max_size) {
+ /* Still a significant amount to transfer */
+
+ current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+ if (migrate_postcopy_ram() &&
+ s->state != MIGRATION_STATUS_POSTCOPY_ACTIVE &&
+ pend_nonpost <= max_size &&
+ atomic_read(&s->start_postcopy)) {
+
+ if (!postcopy_start(s, &old_vm_running)) {
+ current_active_state = MIGRATION_STATUS_POSTCOPY_ACTIVE;
+ entered_postcopy = true;
+ }
+
+ continue;
+ }
+ /* Just another iteration step */
qemu_savevm_state_iterate(s->file);
} else {
trace_migration_thread_low_pending(pending_size);
- migration_completion(s, MIGRATION_STATUS_ACTIVE,
+ migration_completion(s, current_active_state,
&old_vm_running, &start_time);
break;
}
}
if (qemu_file_get_error(s->file)) {
- migrate_set_state(s, MIGRATION_STATUS_ACTIVE,
- MIGRATION_STATUS_FAILED);
+ migrate_set_state(s, current_active_state, MIGRATION_STATUS_FAILED);
+ trace_migration_thread_file_err();
break;
}
current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
@@ -1406,6 +1548,7 @@ static void *migration_thread(void *opaque)
}
}
+ trace_migration_thread_after_loop();
/* If we enabled cpu throttling for auto-converge, turn it off. */
cpu_throttle_stop();
end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
@@ -1415,14 +1558,16 @@ static void *migration_thread(void *opaque)
if (s->state == MIGRATION_STATUS_COMPLETED) {
uint64_t transferred_bytes = qemu_ftell(s->file);
s->total_time = end_time - s->total_time;
- s->downtime = end_time - start_time;
+ if (!entered_postcopy) {
+ s->downtime = end_time - start_time;
+ }
if (s->total_time) {
s->mbps = (((double) transferred_bytes * 8.0) /
((double) s->total_time)) / 1000;
}
runstate_set(RUN_STATE_POSTMIGRATE);
} else {
- if (old_vm_running) {
+ if (old_vm_running && !entered_postcopy) {
vm_start();
}
}
@@ -1445,9 +1590,24 @@ void migrate_fd_connect(MigrationState *s)
/* Notify before starting migration thread */
notifier_list_notify(&migration_state_notifiers, s);
+ /*
+ * Open the return path; currently for postcopy but other things might
+ * also want it.
+ */
+ if (migrate_postcopy_ram()) {
+ if (open_return_path_on_source(s)) {
+ error_report("Unable to open return-path for postcopy");
+ migrate_set_state(s, MIGRATION_STATUS_SETUP,
+ MIGRATION_STATUS_FAILED);
+ migrate_fd_cleanup(s);
+ return;
+ }
+ }
+
migrate_compress_threads_create();
qemu_thread_create(&s->thread, "migration", migration_thread, s,
QEMU_THREAD_JOINABLE);
+ s->migration_thread_running = true;
}
PostcopyState postcopy_state_get(void)