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 786D5C433EF for ; Wed, 27 Apr 2022 08:49:58 +0000 (UTC) Received: from localhost ([::1]:56330 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1njdMz-0003u1-Fa for qemu-devel@archiver.kernel.org; Wed, 27 Apr 2022 04:49:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35042) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njdJp-0008UZ-E7 for qemu-devel@nongnu.org; Wed, 27 Apr 2022 04:46:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:45317) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njdJn-0007ho-N8 for qemu-devel@nongnu.org; Wed, 27 Apr 2022 04:46:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651049199; h=from:from:reply-to: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=gwcu194HBvb8Ksff9n2Zlo6tHmrzGq0NNX1/7weJwm4=; b=RoR2CmEb+wsO1HIonV0hsvUrT4HAFsFba8FcT4dDr11oBEjyAcKKAQxrhOd9phhtqD7dL9 W+O1R85c2dmAs78QdyHHAWgloe5K+Ve6lKck42LUCPAqoRAGhf4wjh/L3CSrId8KOqKtSg oJjPupWXpm0xNNNR/NocLNFHkh4rtuQ= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-327-TUrxAD42MMCtFNEAVluv3w-1; Wed, 27 Apr 2022 04:46:35 -0400 X-MC-Unique: TUrxAD42MMCtFNEAVluv3w-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 73B563C0F086; Wed, 27 Apr 2022 08:46:35 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 744AC5690E5; Wed, 27 Apr 2022 08:46:33 +0000 (UTC) Date: Wed, 27 Apr 2022 09:46:31 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Leonardo Bras Subject: Re: [PATCH v10 7/7] multifd: Implement zero copy write in multifd migration (multifd-zero-copy) Message-ID: References: <20220426230654.637939-1-leobras@redhat.com> <20220426230654.637939-8-leobras@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220426230654.637939-8-leobras@redhat.com> User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Elena Ufimtseva , John G Johnson , Jagannathan Raman , qemu-block@nongnu.org, Juan Quintela , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Peter Xu , Markus Armbruster , Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Fam Zheng , Eric Blake Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Apr 26, 2022 at 08:06:56PM -0300, Leonardo Bras wrote: > Implement zero copy send on nocomp_send_write(), by making use of QIOChannel > writev + flags & flush interface. > > Change multifd_send_sync_main() so flush_zero_copy() can be called > after each iteration in order to make sure all dirty pages are sent before > a new iteration is started. It will also flush at the beginning and at the > end of migration. > > Also make it return -1 if flush_zero_copy() fails, in order to cancel > the migration process, and avoid resuming the guest in the target host > without receiving all current RAM. > > This will work fine on RAM migration because the RAM pages are not usually freed, > and there is no problem on changing the pages content between writev_zero_copy() and > the actual sending of the buffer, because this change will dirty the page and > cause it to be re-sent on a next iteration anyway. > > A lot of locked memory may be needed in order to use multifd migration > with zero-copy enabled, so disabling the feature should be necessary for > low-privileged users trying to perform multifd migrations. > > Signed-off-by: Leonardo Bras > --- > migration/multifd.h | 2 ++ > migration/migration.c | 11 ++++++++++- > migration/multifd.c | 37 +++++++++++++++++++++++++++++++++++-- > migration/socket.c | 5 +++-- > 4 files changed, 50 insertions(+), 5 deletions(-) Reviewed-by: Daniel P. Berrangé With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|