From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42314) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e3zGh-0000dU-0O for qemu-devel@nongnu.org; Mon, 16 Oct 2017 02:52:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e3zGf-0001Oz-Qe for qemu-devel@nongnu.org; Mon, 16 Oct 2017 02:52:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37222) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e3zGf-0001OJ-Hy for qemu-devel@nongnu.org; Mon, 16 Oct 2017 02:52:53 -0400 From: Peter Xu Date: Mon, 16 Oct 2017 14:51:50 +0800 Message-Id: <20171016065216.18162-7-peterx@redhat.com> In-Reply-To: <20171016065216.18162-1-peterx@redhat.com> References: <20171016065216.18162-1-peterx@redhat.com> Subject: [Qemu-devel] [PATCH v3 06/32] migration: allow dst vm pause on postcopy List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Andrea Arcangeli , "Daniel P . Berrange" , Juan Quintela , Alexey Perevalov , "Dr . David Alan Gilbert" , peterx@redhat.com When there is IO error on the incoming channel (e.g., network down), instead of bailing out immediately, we allow the dst vm to switch to the new POSTCOPY_PAUSE state. Currently it is still simple - it waits the new semaphore, until someone poke it for another attempt. Signed-off-by: Peter Xu --- migration/migration.c | 1 + migration/migration.h | 3 +++ migration/savevm.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++-- migration/trace-events | 2 ++ 4 files changed, 64 insertions(+), 2 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 88c5188988..3cc6d4933d 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -147,6 +147,7 @@ MigrationIncomingState *migration_incoming_get_current(void) memset(&mis_current, 0, sizeof(MigrationIncomingState)); qemu_mutex_init(&mis_current.rp_mutex); qemu_event_init(&mis_current.main_thread_load_event, false); + qemu_sem_init(&mis_current.postcopy_pause_sem_dst, 0); once = true; } return &mis_current; diff --git a/migration/migration.h b/migration/migration.h index 065268432d..1280060d54 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -61,6 +61,9 @@ struct MigrationIncomingState { /* The coroutine we should enter (back) after failover */ Coroutine *migration_incoming_co; QemuSemaphore colo_incoming_sem; + + /* notify PAUSED postcopy incoming migrations to try to continue */ + QemuSemaphore postcopy_pause_sem_dst; }; MigrationIncomingState *migration_incoming_get_current(void); diff --git a/migration/savevm.c b/migration/savevm.c index 1da0255cd7..93e308ebf0 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1529,8 +1529,8 @@ static int loadvm_postcopy_ram_handle_discard(MigrationIncomingState *mis, */ static void *postcopy_ram_listen_thread(void *opaque) { - QEMUFile *f = opaque; MigrationIncomingState *mis = migration_incoming_get_current(); + QEMUFile *f = mis->from_src_file; int load_res; migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, @@ -1544,6 +1544,14 @@ static void *postcopy_ram_listen_thread(void *opaque) */ qemu_file_set_blocking(f, true); load_res = qemu_loadvm_state_main(f, mis); + + /* + * This is tricky, but, mis->from_src_file can change after it + * returns, when postcopy recovery happened. In the future, we may + * want a wrapper for the QEMUFile handle. + */ + f = mis->from_src_file; + /* And non-blocking again so we don't block in any cleanup */ qemu_file_set_blocking(f, false); @@ -1626,7 +1634,7 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis) /* Start up the listening thread and wait for it to signal ready */ qemu_sem_init(&mis->listen_thread_sem, 0); qemu_thread_create(&mis->listen_thread, "postcopy/listen", - postcopy_ram_listen_thread, mis->from_src_file, + postcopy_ram_listen_thread, NULL, QEMU_THREAD_DETACHED); qemu_sem_wait(&mis->listen_thread_sem); qemu_sem_destroy(&mis->listen_thread_sem); @@ -2011,11 +2019,44 @@ void qemu_loadvm_state_cleanup(void) } } +/* Return true if we should continue the migration, or false. */ +static bool postcopy_pause_incoming(MigrationIncomingState *mis) +{ + trace_postcopy_pause_incoming(); + + migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE, + MIGRATION_STATUS_POSTCOPY_PAUSED); + + assert(mis->from_src_file); + qemu_file_shutdown(mis->from_src_file); + qemu_fclose(mis->from_src_file); + mis->from_src_file = NULL; + + assert(mis->to_src_file); + qemu_file_shutdown(mis->to_src_file); + qemu_mutex_lock(&mis->rp_mutex); + qemu_fclose(mis->to_src_file); + mis->to_src_file = NULL; + qemu_mutex_unlock(&mis->rp_mutex); + + error_report("Detected IO failure for postcopy. " + "Migration paused."); + + while (mis->state == MIGRATION_STATUS_POSTCOPY_PAUSED) { + qemu_sem_wait(&mis->postcopy_pause_sem_dst); + } + + trace_postcopy_pause_incoming_continued(); + + return true; +} + static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis) { uint8_t section_type; int ret = 0; +retry: while (true) { section_type = qemu_get_byte(f); @@ -2060,6 +2101,21 @@ static int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis) out: if (ret < 0) { qemu_file_set_error(f, ret); + + /* + * Detect whether it is: + * + * 1. postcopy running + * 2. network failure (-EIO) + * + * If so, we try to wait for a recovery. + */ + if (mis->state == MIGRATION_STATUS_POSTCOPY_ACTIVE && + ret == -EIO && postcopy_pause_incoming(mis)) { + /* Reset f to point to the newly created channel */ + f = mis->from_src_file; + goto retry; + } } return ret; } diff --git a/migration/trace-events b/migration/trace-events index da1c63a933..bed1646cd6 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -100,6 +100,8 @@ open_return_path_on_source(void) "" open_return_path_on_source_continue(void) "" postcopy_start(void) "" postcopy_pause_continued(void) "" +postcopy_pause_incoming(void) "" +postcopy_pause_incoming_continued(void) "" postcopy_start_set_run(void) "" source_return_path_thread_bad_end(void) "" source_return_path_thread_end(void) "" -- 2.13.5