From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36938) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejjUg-0006Ln-Hv for qemu-devel@nongnu.org; Thu, 08 Feb 2018 05:31:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ejjUe-0005Ry-FN for qemu-devel@nongnu.org; Thu, 08 Feb 2018 05:31:54 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42922 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ejjUe-0005Rc-9S for qemu-devel@nongnu.org; Thu, 08 Feb 2018 05:31:52 -0500 From: Peter Xu Date: Thu, 8 Feb 2018 18:31:09 +0800 Message-Id: <20180208103132.28452-6-peterx@redhat.com> In-Reply-To: <20180208103132.28452-1-peterx@redhat.com> References: <20180208103132.28452-1-peterx@redhat.com> Subject: [Qemu-devel] [PATCH v6 05/28] migration: implement "postcopy-pause" src logic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Alexey Perevalov , "Daniel P . Berrange" , Juan Quintela , Andrea Arcangeli , "Dr . David Alan Gilbert" , peterx@redhat.com Now when network down for postcopy, the source side will not fail the migration. Instead we convert the status into this new paused state, and we will try to wait for a rescue in the future. If a recovery is detected, migration_thread() will reset its local variables to prepare for that. Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Peter Xu --- migration/migration.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++--- migration/migration.h | 3 ++ migration/trace-events | 1 + 3 files changed, 97 insertions(+), 6 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index e8a79bb181..de5ee9c1d4 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2154,6 +2154,80 @@ bool migrate_colo_enabled(void) return s->enabled_capabilities[MIGRATION_CAPABILITY_X_COLO]; } +typedef enum MigThrError { + /* No error detected */ + MIG_THR_ERR_NONE = 0, + /* Detected error, but resumed successfully */ + MIG_THR_ERR_RECOVERED = 1, + /* Detected fatal error, need to exit */ + MIG_THR_ERR_FATAL = 2, +} MigThrError; + +/* + * We don't return until we are in a safe state to continue current + * postcopy migration. Returns MIG_THR_ERR_RECOVERED if recovered, or + * MIG_THR_ERR_FATAL if unrecovery failure happened. + */ +static MigThrError postcopy_pause(MigrationState *s) +{ + assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE); + migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, + MIGRATION_STATUS_POSTCOPY_PAUSED); + + /* Current channel is possibly broken. Release it. */ + assert(s->to_dst_file); + qemu_file_shutdown(s->to_dst_file); + qemu_fclose(s->to_dst_file); + s->to_dst_file = NULL; + + error_report("Detected IO failure for postcopy. " + "Migration paused."); + + /* + * We wait until things fixed up. Then someone will setup the + * status back for us. + */ + while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) { + qemu_sem_wait(&s->postcopy_pause_sem); + } + + trace_postcopy_pause_continued(); + + return MIG_THR_ERR_RECOVERED; +} + +static MigThrError migration_detect_error(MigrationState *s) +{ + int ret; + + /* Try to detect any file errors */ + ret = qemu_file_get_error(s->to_dst_file); + + if (!ret) { + /* Everything is fine */ + return MIG_THR_ERR_NONE; + } + + if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE && ret == -EIO) { + /* + * For postcopy, we allow the network to be down for a + * while. After that, it can be continued by a + * recovery phase. + */ + return postcopy_pause(s); + } else { + /* + * For precopy (or postcopy with error outside IO), we fail + * with no time. + */ + migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED); + trace_migration_thread_file_err(); + + /* Time to stop the migration, now. */ + return MIG_THR_ERR_FATAL; + } +} + static void migration_calculate_complete(MigrationState *s) { uint64_t bytes = qemu_ftell(s->to_dst_file); @@ -2310,6 +2384,7 @@ static void *migration_thread(void *opaque) { MigrationState *s = opaque; int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST); + MigThrError thr_error; rcu_register_thread(); @@ -2359,13 +2434,22 @@ static void *migration_thread(void *opaque) } } - if (qemu_file_get_error(s->to_dst_file)) { - if (migration_is_setup_or_active(s->state)) { - migrate_set_state(&s->state, s->state, - MIGRATION_STATUS_FAILED); - } - trace_migration_thread_file_err(); + /* + * Try to detect any kind of failures, and see whether we + * should stop the migration now. + */ + thr_error = migration_detect_error(s); + if (thr_error == MIG_THR_ERR_FATAL) { + /* Stop migration */ break; + } else if (thr_error == MIG_THR_ERR_RECOVERED) { + /* + * Just recovered from a e.g. network failure, reset all + * the local variables. This is important to avoid + * breaking transferred_bytes and bandwidth calculation + */ + s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); + s->iteration_initial_bytes = 0; } current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); @@ -2523,6 +2607,7 @@ static void migration_instance_finalize(Object *obj) g_free(params->tls_hostname); g_free(params->tls_creds); qemu_sem_destroy(&ms->pause_sem); + qemu_sem_destroy(&ms->postcopy_pause_sem); } static void migration_instance_init(Object *obj) @@ -2551,6 +2636,8 @@ static void migration_instance_init(Object *obj) params->has_x_multifd_channels = true; params->has_x_multifd_page_count = true; params->has_xbzrle_cache_size = true; + + qemu_sem_init(&ms->postcopy_pause_sem, 0); } /* diff --git a/migration/migration.h b/migration/migration.h index eb36ea9278..3e4af0a831 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -178,6 +178,9 @@ struct MigrationState bool send_configuration; /* Whether we send section footer during migration */ bool send_section_footer; + + /* Needed by postcopy-pause state */ + QemuSemaphore postcopy_pause_sem; }; void migrate_set_state(int *state, int old_state, int new_state); diff --git a/migration/trace-events b/migration/trace-events index 93961dea16..7afbb3e791 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -99,6 +99,7 @@ migration_thread_setup_complete(void) "" open_return_path_on_source(void) "" open_return_path_on_source_continue(void) "" postcopy_start(void) "" +postcopy_pause_continued(void) "" postcopy_start_set_run(void) "" source_return_path_thread_bad_end(void) "" source_return_path_thread_end(void) "" -- 2.14.3