From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1A52C433FF for ; Wed, 7 Aug 2019 18:48:57 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C75902086D for ; Wed, 7 Aug 2019 18:48:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C75902086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44484 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hvQzZ-0000L9-0W for qemu-devel@archiver.kernel.org; Wed, 07 Aug 2019 14:48:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43283) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hvQyw-0008Mb-7x for qemu-devel@nongnu.org; Wed, 07 Aug 2019 14:48:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hvQyu-0005S1-PI for qemu-devel@nongnu.org; Wed, 07 Aug 2019 14:48:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57230) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hvQyu-0005QI-HK for qemu-devel@nongnu.org; Wed, 07 Aug 2019 14:48:16 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D101030017A7; Wed, 7 Aug 2019 18:48:15 +0000 (UTC) Received: from work-vm (ovpn-117-204.ams2.redhat.com [10.36.117.204]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4BB4160BE0; Wed, 7 Aug 2019 18:48:11 +0000 (UTC) Date: Wed, 7 Aug 2019 19:48:08 +0100 From: "Dr. David Alan Gilbert" To: Ivan Ren Message-ID: <20190807184808.GS27871@work-vm> References: <1564741121-1840-1-git-send-email-ivanren@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1564741121-1840-1-git-send-email-ivanren@tencent.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Wed, 07 Aug 2019 18:48:15 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v3] migration: always initial ram_counters for a new migration X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, richardw.yang@linux.intel.com, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Ivan Ren (renyime@gmail.com) wrote: > From: Ivan Ren > > This patch fix a multifd migration bug in migration speed calculation, this > problem can be reproduced as follows: > 1. start a vm and give a heavy memory write stress to prevent the vm be > successfully migrated to destination > 2. begin a migration with multifd > 3. migrate for a long time [actually, this can be measured by transferred bytes] > 4. migrate cancel > 5. begin a new migration with multifd, the migration will directly run into > migration_completion phase > > Reason as follows: > > Migration update bandwidth and s->threshold_size in function > migration_update_counters after BUFFER_DELAY time: > > current_bytes = migration_total_bytes(s); > transferred = current_bytes - s->iteration_initial_bytes; > time_spent = current_time - s->iteration_start_time; > bandwidth = (double)transferred / time_spent; > s->threshold_size = bandwidth * s->parameters.downtime_limit; > > In multifd migration, migration_total_bytes function return > qemu_ftell(s->to_dst_file) + ram_counters.multifd_bytes. > s->iteration_initial_bytes will be initialized to 0 at every new migration, > but ram_counters is a global variable, and history migration data will be > accumulated. So if the ram_counters.multifd_bytes is big enough, it may lead > pending_size >= s->threshold_size become false in migration_iteration_run > after the first migration_update_counters. > > Signed-off-by: Ivan Ren > Reviewed-by: Juan Quintela > Suggested-by: Wei Yang Thank you, Queued > --- > v2->v3: > - fix the bug of update_iteration_initial_status function prototype > > v1->v2: > - Add interface update_iteration_initial_status to update statistic fields > at the same time to avoid info mismatch lead wrong calculation result. > > migration/migration.c | 25 +++++++++++++++++++------ > migration/savevm.c | 1 + > 2 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/migration/migration.c b/migration/migration.c > index 8a607fe1e2..bea9b1d796 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -1908,6 +1908,11 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc, > } > > migrate_init(s); > + /* > + * set ram_counters memory to zero for a > + * new migration > + */ > + memset(&ram_counters, 0, sizeof(ram_counters)); > > return true; > } > @@ -3025,6 +3030,17 @@ static void migration_calculate_complete(MigrationState *s) > } > } > > +static void update_iteration_initial_status(MigrationState *s) > +{ > + /* > + * Update these three fields at the same time to avoid mismatch info lead > + * wrong speed calculation. > + */ > + s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > + s->iteration_initial_bytes = migration_total_bytes(s); > + s->iteration_initial_pages = ram_get_total_transferred_pages(); > +} > + > static void migration_update_counters(MigrationState *s, > int64_t current_time) > { > @@ -3060,9 +3076,7 @@ static void migration_update_counters(MigrationState *s, > > qemu_file_reset_rate_limit(s->to_dst_file); > > - s->iteration_start_time = current_time; > - s->iteration_initial_bytes = current_bytes; > - s->iteration_initial_pages = ram_get_total_transferred_pages(); > + update_iteration_initial_status(s); > > trace_migrate_transferred(transferred, time_spent, > bandwidth, s->threshold_size); > @@ -3186,7 +3200,7 @@ static void *migration_thread(void *opaque) > rcu_register_thread(); > > object_ref(OBJECT(s)); > - s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > + update_iteration_initial_status(s); > > qemu_savevm_state_header(s->to_dst_file); > > @@ -3251,8 +3265,7 @@ static void *migration_thread(void *opaque) > * 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; > + update_iteration_initial_status(s); > } > > current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > diff --git a/migration/savevm.c b/migration/savevm.c > index 79ed44d475..480c511b19 100644 > --- a/migration/savevm.c > +++ b/migration/savevm.c > @@ -1424,6 +1424,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp) > } > > migrate_init(ms); > + memset(&ram_counters, 0, sizeof(ram_counters)); > ms->to_dst_file = f; > > qemu_mutex_unlock_iothread(); > -- > 2.17.2 (Apple Git-113) > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK