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Postcopy: Postcopy startup in migration thread

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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>
This commit is contained in:
Dr. David Alan Gilbert 2015-11-05 18:11:05 +00:00 committed by Juan Quintela
parent f0a227ade4
commit 1d34e4bf6a
3 changed files with 174 additions and 7 deletions
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3
include/migration/migration.h
View File

@ -135,6 +135,9 @@ struct MigrationState
/* Flag set once the migration has been asked to enter postcopy */
bool start_postcopy;
/* Flag set once the migration thread is running (and needs joining) */
bool migration_thread_running;
};
void process_incoming_migration(QEMUFile *f);

174
migration/migration.c
View File

@ -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)

4
trace-events
View File

@ -1453,9 +1453,13 @@ migrate_fd_error(void) ""
migrate_fd_cancel(void) ""
migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")"
migrate_send_rp_message(int msg_type, uint16_t len) "%d: len %d"
migration_thread_after_loop(void) ""
migration_thread_file_err(void) ""
migration_thread_setup_complete(void) ""
open_return_path_on_source(void) ""
open_return_path_on_source_continue(void) ""
postcopy_start(void) ""
postcopy_start_set_run(void) ""
source_return_path_thread_bad_end(void) ""
source_return_path_thread_end(void) ""
source_return_path_thread_entry(void) ""