{"id":807512,"url":"http://patchwork.ozlabs.org/api/1.0/patches/807512/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<1504081950-2528-10-git-send-email-peterx@redhat.com>","date":"2017-08-30T08:32:06","name":"[RFC,v2,09/33] migration: implement \"postcopy-pause\" src logic","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"ae3515ac9d7239c17feb2124569dff01c31a46c3","submitter":{"id":67717,"url":"http://patchwork.ozlabs.org/api/1.0/people/67717/?format=json","name":"Peter Xu","email":"peterx@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/1504081950-2528-10-git-send-email-peterx@redhat.com/mbox/","series":[{"id":552,"url":"http://patchwork.ozlabs.org/api/1.0/series/552/?format=json","date":"2017-08-30T08:31:59","name":"Migration: postcopy failure recovery","version":2,"mbox":"http://patchwork.ozlabs.org/series/552/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/807512/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ext-mx03.extmail.prod.ext.phx2.redhat.com;\n\tdmarc=none (p=none dis=none) header.from=redhat.com","ext-mx03.extmail.prod.ext.phx2.redhat.com;\n\tspf=fail smtp.mailfrom=peterx@redhat.com"],"Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xhzlL3FN3z9t2Q\n\tfor ;\n\tWed, 30 Aug 2017 18:51:58 +1000 (AEST)","from localhost ([::1]:49096 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dmyj6-0006E8-06\n\tfor incoming@patchwork.ozlabs.org; Wed, 30 Aug 2017 04:51:56 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:34061)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dmyR5-00078n-2y\n\tfor qemu-devel@nongnu.org; Wed, 30 Aug 2017 04:33:20 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dmyR3-0003ID-Ng\n\tfor qemu-devel@nongnu.org; Wed, 30 Aug 2017 04:33:19 -0400","from mx1.redhat.com ([209.132.183.28]:47414)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from ) id 1dmyR3-0003Hs-FH\n\tfor qemu-devel@nongnu.org; Wed, 30 Aug 2017 04:33:17 -0400","from smtp.corp.redhat.com\n\t(int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id 7FF1E80F6C;\n\tWed, 30 Aug 2017 08:33:16 +0000 (UTC)","from pxdev.xzpeter.org.com (dhcp-14-103.nay.redhat.com\n\t[10.66.14.103])\n\tby smtp.corp.redhat.com (Postfix) with ESMTP id 7C022871DD;\n\tWed, 30 Aug 2017 08:33:13 +0000 (UTC)"],"DMARC-Filter":"OpenDMARC Filter v1.3.2 mx1.redhat.com 7FF1E80F6C","From":"Peter Xu ","To":"qemu-devel@nongnu.org","Date":"Wed, 30 Aug 2017 16:32:06 +0800","Message-Id":"<1504081950-2528-10-git-send-email-peterx@redhat.com>","In-Reply-To":"<1504081950-2528-1-git-send-email-peterx@redhat.com>","References":"<1504081950-2528-1-git-send-email-peterx@redhat.com>","X-Scanned-By":"MIMEDefang 2.79 on 10.5.11.15","X-Greylist":"Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.27]);\n\tWed, 30 Aug 2017 08:33:16 +0000 (UTC)","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"209.132.183.28","Subject":"[Qemu-devel] [RFC v2 09/33] migration: implement \"postcopy-pause\"\n\tsrc logic","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"Laurent Vivier ,\n\tAndrea Arcangeli , \n\tJuan Quintela ,\n\tAlexey Perevalov , peterx@redhat.com,\n\t\"Dr . David Alan Gilbert\" ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"},"content":"Now when network down for postcopy, the source side will not fail the\nmigration. Instead we convert the status into this new paused state, and\nwe will try to wait for a rescue in the future.\n\nIf a recovery is detected, migration_thread() will reset its local\nvariables to prepare for that.\n\nSigned-off-by: Peter Xu \n---\n migration/migration.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++---\n migration/migration.h | 3 ++\n migration/trace-events | 1 +\n 3 files changed, 98 insertions(+), 4 deletions(-)","diff":"diff --git a/migration/migration.c b/migration/migration.c\nindex f6130db..8d26ea8 100644\n--- a/migration/migration.c\n+++ b/migration/migration.c\n@@ -993,6 +993,8 @@ static void migrate_fd_cleanup(void *opaque)\n \n notifier_list_notify(&migration_state_notifiers, s);\n block_cleanup_parameters(s);\n+\n+ qemu_sem_destroy(&s->postcopy_pause_sem);\n }\n \n void migrate_fd_error(MigrationState *s, const Error *error)\n@@ -1136,6 +1138,7 @@ MigrationState *migrate_init(void)\n s->migration_thread_running = false;\n error_free(s->error);\n s->error = NULL;\n+ qemu_sem_init(&s->postcopy_pause_sem, 0);\n \n migrate_set_state(&s->state, MIGRATION_STATUS_NONE, MIGRATION_STATUS_SETUP);\n \n@@ -1938,6 +1941,80 @@ bool migrate_colo_enabled(void)\n return s->enabled_capabilities[MIGRATION_CAPABILITY_X_COLO];\n }\n \n+typedef enum MigThrError {\n+ /* No error detected */\n+ MIG_THR_ERR_NONE = 0,\n+ /* Detected error, but resumed successfully */\n+ MIG_THR_ERR_RECOVERED = 1,\n+ /* Detected fatal error, need to exit */\n+ MIG_THR_ERR_FATAL = 2,\n+} MigThrError;\n+\n+/*\n+ * We don't return until we are in a safe state to continue current\n+ * postcopy migration. Returns MIG_THR_ERR_RECOVERED if recovered, or\n+ * MIG_THR_ERR_FATAL if unrecovery failure happened.\n+ */\n+static MigThrError postcopy_pause(MigrationState *s)\n+{\n+ assert(s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);\n+ migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,\n+ MIGRATION_STATUS_POSTCOPY_PAUSED);\n+\n+ /* Current channel is possibly broken. Release it. */\n+ assert(s->to_dst_file);\n+ qemu_file_shutdown(s->to_dst_file);\n+ qemu_fclose(s->to_dst_file);\n+ s->to_dst_file = NULL;\n+\n+ error_report(\"Detected IO failure for postcopy. \"\n+ \"Migration paused.\");\n+\n+ /*\n+ * We wait until things fixed up. Then someone will setup the\n+ * status back for us.\n+ */\n+ while (s->state == MIGRATION_STATUS_POSTCOPY_PAUSED) {\n+ qemu_sem_wait(&s->postcopy_pause_sem);\n+ }\n+\n+ trace_postcopy_pause_continued();\n+\n+ return MIG_THR_ERR_RECOVERED;\n+}\n+\n+static MigThrError migration_detect_error(MigrationState *s)\n+{\n+ int ret;\n+\n+ /* Try to detect any file errors */\n+ ret = qemu_file_get_error(s->to_dst_file);\n+\n+ if (!ret) {\n+ /* Everything is fine */\n+ return MIG_THR_ERR_NONE;\n+ }\n+\n+ if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE && ret == -EIO) {\n+ /*\n+ * For postcopy, we allow the network to be down for a\n+ * while. After that, it can be continued by a\n+ * recovery phase.\n+ */\n+ return postcopy_pause(s);\n+ } else {\n+ /*\n+ * For precopy (or postcopy with error outside IO), we fail\n+ * with no time.\n+ */\n+ migrate_set_state(&s->state, s->state, MIGRATION_STATUS_FAILED);\n+ trace_migration_thread_file_err();\n+\n+ /* Time to stop the migration, now. */\n+ return MIG_THR_ERR_FATAL;\n+ }\n+}\n+\n /*\n * Master migration thread on the source VM.\n * It drives the migration and pumps the data down the outgoing channel.\n@@ -1962,6 +2039,7 @@ static void *migration_thread(void *opaque)\n /* The active state we expect to be in; ACTIVE or POSTCOPY_ACTIVE */\n enum MigrationStatus current_active_state = MIGRATION_STATUS_ACTIVE;\n bool enable_colo = migrate_colo_enabled();\n+ MigThrError thr_error;\n \n rcu_register_thread();\n \n@@ -2034,12 +2112,24 @@ static void *migration_thread(void *opaque)\n }\n }\n \n- if (qemu_file_get_error(s->to_dst_file)) {\n- migrate_set_state(&s->state, current_active_state,\n- MIGRATION_STATUS_FAILED);\n- trace_migration_thread_file_err();\n+ /*\n+ * Try to detect any kind of failures, and see whether we\n+ * should stop the migration now.\n+ */\n+ thr_error = migration_detect_error(s);\n+ if (thr_error == MIG_THR_ERR_FATAL) {\n+ /* Stop migration */\n break;\n+ } else if (thr_error == MIG_THR_ERR_RECOVERED) {\n+ /*\n+ * Just recovered from a e.g. network failure, reset all\n+ * the local variables. This is important to avoid\n+ * breaking transferred_bytes and bandwidth calculation\n+ */\n+ initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);\n+ initial_bytes = 0;\n }\n+\n current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);\n if (current_time >= initial_time + BUFFER_DELAY) {\n uint64_t transferred_bytes = qemu_ftell(s->to_dst_file) -\ndiff --git a/migration/migration.h b/migration/migration.h\nindex 70e3094..0c957c9 100644\n--- a/migration/migration.h\n+++ b/migration/migration.h\n@@ -149,6 +149,9 @@ struct MigrationState\n bool send_configuration;\n /* Whether we send section footer during migration */\n bool send_section_footer;\n+\n+ /* Needed by postcopy-pause state */\n+ QemuSemaphore postcopy_pause_sem;\n };\n \n void migrate_set_state(int *state, int old_state, int new_state);\ndiff --git a/migration/trace-events b/migration/trace-events\nindex d2910a6..907564b 100644\n--- a/migration/trace-events\n+++ b/migration/trace-events\n@@ -98,6 +98,7 @@ migration_thread_setup_complete(void) \"\"\n open_return_path_on_source(void) \"\"\n open_return_path_on_source_continue(void) \"\"\n postcopy_start(void) \"\"\n+postcopy_pause_continued(void) \"\"\n postcopy_start_set_run(void) \"\"\n source_return_path_thread_bad_end(void) \"\"\n source_return_path_thread_end(void) \"\"\n","prefixes":["RFC","v2","09/33"]}