On Wed, Feb 25, 2015 at 04:51:53PM +0000, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > Rework the migration thread to setup and start postcopy. > > Signed-off-by: Dr. David Alan Gilbert > --- > include/migration/migration.h | 3 + > migration/migration.c | 161 ++++++++++++++++++++++++++++++++++++++++-- > trace-events | 4 ++ > 3 files changed, 164 insertions(+), 4 deletions(-) > > diff --git a/include/migration/migration.h b/include/migration/migration.h > index 821d561..2c607e7 100644 > --- a/include/migration/migration.h > +++ b/include/migration/migration.h > @@ -131,6 +131,9 @@ 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 started_migration_thread; > + > /* bitmap of pages that have been sent at least once > * only maintained and used in postcopy at the moment > * where it's used to send the dirtymap at the start > diff --git a/migration/migration.c b/migration/migration.c > index b1ad7b1..6bf9c8d 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -468,7 +468,10 @@ 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->started_migration_thread) { > + qemu_thread_join(&s->thread); > + s->started_migration_thread = false; > + } > qemu_mutex_lock_iothread(); > > qemu_fclose(s->file); > @@ -874,7 +877,6 @@ out: > return NULL; > } > > -__attribute__ (( unused )) /* Until later in patch series */ > static int open_outgoing_return_path(MigrationState *ms) > { > > @@ -911,23 +913,141 @@ static void await_outgoing_return_path_close(MigrationState *ms) > } > > /* > + * 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, MIG_STATE_ACTIVE, MIG_STATE_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(); I think that needs some explanation. Why are you doing a wakeup on the source host? > + 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 MIG_STATE_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); > + > + /* > + * We need to leave the fd free for page transfers during the > + * loading of the device state, so wrap all the remaining > + * commands and state into a package that gets sent in one go > + */ > + QEMUFile *fb = qemu_bufopen("w", NULL); > + if (!fb) { > + error_report("Failed to create buffered file"); > + goto fail; > + } > + > + qemu_savevm_state_complete(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 (qsb_get_length(qsb) > MAX_VM_CMD_PACKAGED_SIZE) { > + error_report("postcopy_start: Unreasonably large packaged state: %lu", > + (unsigned long)(qsb_get_length(qsb))); > + goto fail_closefb; > + } > + qemu_savevm_send_packaged(ms->file, qsb); > + 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, MIG_STATE_POSTCOPY_ACTIVE, MIG_STATE_ERROR); > + } > + > + return ret; > + > +fail_closefb: > + qemu_fclose(fb); > +fail: > + migrate_set_state(ms, MIG_STATE_POSTCOPY_ACTIVE, MIG_STATE_ERROR); > + qemu_mutex_unlock_iothread(); > + return -1; > +} > + > +/* > * Master migration thread on the source VM. > * It drives the migration and pumps the data down the outgoing channel. > */ > 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; > int64_t max_size = 0; > int64_t start_time = initial_time; > bool old_vm_running = false; > + bool entered_postcopy = false; > + /* The active state we expect to be in; ACTIVE or POSTCOPY_ACTIVE */ > + enum MigrationPhase current_active_type = MIG_STATE_ACTIVE; > > 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_type = MIG_STATE_ACTIVE; > migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ACTIVE); > > trace_migration_thread_setup_complete(); > @@ -946,6 +1066,22 @@ 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 != MIG_STATE_POSTCOPY_ACTIVE && > + pend_nonpost <= max_size && > + atomic_read(&s->start_postcopy)) { > + > + if (!postcopy_start(s, &old_vm_running)) { > + current_active_type = MIG_STATE_POSTCOPY_ACTIVE; > + entered_postcopy = true; Do you need entered_postcopy, or could you just use the existing MIG_STATE variable? > + } > + > + continue; > + } > + /* Just another iteration step */ > qemu_savevm_state_iterate(s->file); > } else { > int ret; > @@ -975,7 +1111,8 @@ static void *migration_thread(void *opaque) > } > > if (qemu_file_get_error(s->file)) { > - migrate_set_state(s, MIG_STATE_ACTIVE, MIG_STATE_ERROR); > + migrate_set_state(s, current_active_type, MIG_STATE_ERROR); > + trace_migration_thread_file_err(); > break; > } > current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > @@ -1006,12 +1143,15 @@ static void *migration_thread(void *opaque) > } > } > > + trace_migration_thread_after_loop(); > qemu_mutex_lock_iothread(); > if (s->state == MIG_STATE_COMPLETED) { > int64_t end_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > 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; > @@ -1043,8 +1183,21 @@ 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_outgoing_return_path(s)) { > + error_report("Unable to open return-path for postcopy"); > + migrate_set_state(s, MIG_STATE_SETUP, MIG_STATE_ERROR); > + migrate_fd_cleanup(s); > + return; > + } > + } > + > qemu_thread_create(&s->thread, "migration", migration_thread, s, > QEMU_THREAD_JOINABLE); > + s->started_migration_thread = true; > } > > PostcopyState postcopy_state_get(MigrationIncomingState *mis) > diff --git a/trace-events b/trace-events > index 59dea4c..ed8bbe2 100644 > --- a/trace-events > +++ b/trace-events > @@ -1404,9 +1404,13 @@ 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 cmd, uint16_t len) "cmd=%d, len=%d" > +migration_thread_after_loop(void) "" > +migration_thread_file_err(void) "" > migration_thread_setup_complete(void) "" > open_outgoing_return_path(void) "" > open_outgoing_return_path_continue(void) "" > +postcopy_start(void) "" > +postcopy_start_set_run(void) "" > source_return_path_thread_bad_end(void) "" > source_return_path_bad_header_com(void) "" > source_return_path_thread_end(void) "" -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson