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 7C709C48BF6 for ; Thu, 29 Feb 2024 05:42:21 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rfZB7-0006r5-LQ; Thu, 29 Feb 2024 00:41:57 -0500 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 1rfZB5-0006qo-F4 for qemu-devel@nongnu.org; Thu, 29 Feb 2024 00:41:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rfZB3-0002mk-Sl for qemu-devel@nongnu.org; Thu, 29 Feb 2024 00:41:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709185313; 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=gum77zfMkvy+oPQiLKTAERDSIdzd08t1BH9kcDdJ120=; b=GGmNy0IKpSdusVZf2G2EZgZUHoSTFg/7Aim4Q63wRItMk4mS2F/I49yeybUR3uDEq4evw0 JllAe7Nwv4suIWXzCfiOQaNd/MXXkTtEQT0cDIoZKPmuaf7Bojk8yySR3vxc6nPmXVgwET v/a68bvtzih7oFJ91o6I0JvBdP2SGeY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-621-dXEiRyVzOyODOJDws-xRmw-1; Thu, 29 Feb 2024 00:41:49 -0500 X-MC-Unique: dXEiRyVzOyODOJDws-xRmw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3405388FBA8; Thu, 29 Feb 2024 05:41:49 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.193.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0BE4B200A382; Thu, 29 Feb 2024 05:41:49 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id CAE9221E66D0; Thu, 29 Feb 2024 06:41:47 +0100 (CET) From: Markus Armbruster To: Hao Xiang Cc: pbonzini@redhat.com, berrange@redhat.com, eduardo@habkost.net, peterx@redhat.com, farosas@suse.de, eblake@redhat.com, thuth@redhat.com, lvivier@redhat.com, jdenemar@redhat.com, marcel.apfelbaum@gmail.com, philmd@linaro.org, wangyanan55@huawei.com, qemu-devel@nongnu.org Subject: Re: [External] Re: [PATCH v3 2/7] migration/multifd: Implement zero page transmission on the multifd thread. In-Reply-To: (Hao Xiang's message of "Wed, 28 Feb 2024 10:45:29 -0800") References: <20240226195654.934709-1-hao.xiang@bytedance.com> <20240226195654.934709-3-hao.xiang@bytedance.com> <871q8w29zx.fsf@pond.sub.org> Date: Thu, 29 Feb 2024 06:41:47 +0100 Message-ID: <87a5nju8ro.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.102, 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_H2=-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 Hao Xiang writes: > On Wed, Feb 28, 2024 at 1:50=E2=80=AFAM Markus Armbruster wrote: >> >> Hao Xiang writes: >> >> > 1. Add zero_pages field in MultiFDPacket_t. >> > 2. Implements the zero page detection and handling on the multifd >> > threads for non-compression, zlib and zstd compression backends. >> > 3. Added a new value 'multifd' in ZeroPageDetection enumeration. >> > 4. Handle migration QEMU9.0 -> QEMU8.2 compatibility. >> > 5. Adds zero page counters and updates multifd send/receive tracing >> > format to track the newly added counters. >> > >> > Signed-off-by: Hao Xiang >> >> [...] >> >> > diff --git a/qapi/migration.json b/qapi/migration.json >> > index 1e66272f8f..5a1bb8ad62 100644 >> > --- a/qapi/migration.json >> > +++ b/qapi/migration.json >> > @@ -660,10 +660,13 @@ >> > # >> > # @legacy: Perform zero page checking from main migration thread. >> > # >> > +# @multifd: Perform zero page checking from multifd sender thread. >> > +# >> > # Since: 9.0 >> > +# >> > ## >> > { 'enum': 'ZeroPageDetection', >> > - 'data': [ 'none', 'legacy' ] } >> > + 'data': [ 'none', 'legacy', 'multifd' ] } >> > >> > ## >> > # @BitmapMigrationBitmapAliasTransform: >> >> What happens when you set "zero-page-detection": "multifd" *without* >> enabling multifd migration? > > Very good question! Right now the behavior is that if "multifd > migration" is not enabled, it goes through the legacy code path and > the "multifd zero page" option is ignored. The legacy path has its own > zero page checking and will run the same way as before. This is for > backward compatibility. We need one of two improvements then: 1. Make "zero-page-detection" reject value "multifd" when multifd migration is not enabled. Document this: "Requires migration capability @multifd" or similar. 2. Document that "multifd" means multifd only when multifd is enabled, else same as "legacy". I prefer 1., because it's easier to document. But migration maintainers may have their own preference. Peter, Fabiano?