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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 07E67EB64D9 for ; Thu, 6 Jul 2023 15:00:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qHQS7-0003HN-8O; Thu, 06 Jul 2023 10:59:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qHQS1-0003H6-LL for qemu-devel@nongnu.org; Thu, 06 Jul 2023 10:59:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qHQRy-0003Bl-Fm for qemu-devel@nongnu.org; Thu, 06 Jul 2023 10:59:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1688655557; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Jr15GtauzOZy4UNNTLDRlqgzGqok5Y017suwWAGDhnA=; b=WnsGeVIv70guII8mZlo4AJyvWDeMHuaJbhjksZ6LcmujwBNSAVvbCTFUyTgIpabz4E2ypl GSuhzaD8JvQM5rj0UK5g8/pLFodOuRhh8S/DU5tDjFuqV9oCMSciVOAYojVy6tQNJavtE8 5YH6v6GhGnB29RVU7BFo75pl1CWockU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-230-8KlKpdTGNTiA3O2g1LgQow-1; Thu, 06 Jul 2023 10:59:13 -0400 X-MC-Unique: 8KlKpdTGNTiA3O2g1LgQow-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B3C0A185A794; Thu, 6 Jul 2023 14:59:12 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.65]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 91B57492B02; Thu, 6 Jul 2023 14:59:12 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8588F21E6A1F; Thu, 6 Jul 2023 16:59:11 +0200 (CEST) From: Markus Armbruster To: ~hyman Cc: qemu-devel , ~hyman , Peter Xu , Paolo Bonzini , Juan Quintela , "Dr. David Alan Gilbert" , Eric Blake , Markus Armbruster , Thomas Huth , Laurent Vivier , Richard Henderson , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH QEMU v7 4/9] migration: Introduce dirty-limit capability References: <168853615963.17240.15832775267134683267-4@git.sr.ht> Date: Thu, 06 Jul 2023 16:59:11 +0200 In-Reply-To: <168853615963.17240.15832775267134683267-4@git.sr.ht> (hyman@git.sr.ht's message of "Wed, 07 Jun 2023 23:30:50 +0800") Message-ID: <877crdozls.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org ~hyman writes: > From: Hyman Huang(=E9=BB=84=E5=8B=87) > > Introduce migration dirty-limit capability, which can > be turned on before live migration and limit dirty > page rate durty live migration. > > Introduce migrate_dirty_limit function to help check > if dirty-limit capability enabled during live migration. > > Meanwhile, refactor vcpu_dirty_rate_stat_collect > so that period can be configured instead of hardcoded. > > dirty-limit capability is kind of like auto-converge > but using dirty limit instead of traditional cpu-throttle > to throttle guest down. To enable this feature, turn on > the dirty-limit capability before live migration using > migrate-set-capabilities, and set the parameters > "x-vcpu-dirty-limit-period", "vcpu-dirty-limit" suitably > to speed up convergence. > > Signed-off-by: Hyman Huang(=E9=BB=84=E5=8B=87) > Acked-by: Peter Xu > Reviewed-by: Juan Quintela [...] > diff --git a/migration/options.h b/migration/options.h > index 9aaf363322..b5a950d4e4 100644 > --- a/migration/options.h > +++ b/migration/options.h > @@ -24,6 +24,7 @@ extern Property migration_properties[]; > /* capabilities */ >=20=20 > bool migrate_auto_converge(void); > +bool migrate_dirty_limit(void); > bool migrate_background_snapshot(void); > bool migrate_block(void); > bool migrate_colo(void); > diff --git a/qapi/migration.json b/qapi/migration.json > index aa590dbf0e..cc51835cdd 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -497,6 +497,16 @@ > # are present. 'return-path' capability must be enabled to use > # it. (since 8.1) > # > +# @dirty-limit: If enabled, migration will use the dirty-limit algo to > +# throttle down guest instead of auto-converge algo. > +# Throttle algo only works when vCPU's dirtyrate greater > +# than 'vcpu-dirty-limit', read processes in guest os > +# aren't penalized any more, so this algo can improve > +# performance of vCPU during live migration. This is an > +# optional performance feature and should not affect the > +# correctness of the existing auto-converge algo. > +# (since 8.1) > +# Please format like # @dirty-limit: If enabled, migration will use the dirty-limit algo to # throttle down guest instead of auto-converge algo. Throttle # algo only works when vCPU's dirtyrate greater than # 'vcpu-dirty-limit', read processes in guest os aren't penalized # any more, so this algo can improve performance of vCPU during # live migration. This is an optional performance feature and # should not affect the correctness of the existing auto-converge # algo. (since 8.1) to blend in with recent commit a937b6aa739 (qapi: Reformat doc comments to conform to current conventions). "Dirty rate" with a space, because that's how we spell it elsewhere. Moreover, "algo" is not a word, "algorithm" is :) Is "the dirty-limit algorithm" defined anywhere?=20=20 More word-smithing is needed, but I'd like to get the reference to "the dirty-limit algorithm" clarified first. > # Features: > # > # @unstable: Members @x-colo and @x-ignore-shared are experimental. > @@ -512,7 +522,8 @@ > 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate', > { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] }, > 'validate-uuid', 'background-snapshot', > - 'zero-copy-send', 'postcopy-preempt', 'switchover-ack'] } > + 'zero-copy-send', 'postcopy-preempt', 'switchover-ack', > + 'dirty-limit'] } >=20=20 > ## > # @MigrationCapabilityStatus: [...]