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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 0A7BBC433ED for ; Fri, 7 May 2021 09:49:31 +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 8693A61451 for ; Fri, 7 May 2021 09:49:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8693A61451 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56616 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lex6v-0008DD-Ip for qemu-devel@archiver.kernel.org; Fri, 07 May 2021 05:49:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51622) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lex4i-00076f-0K for qemu-devel@nongnu.org; Fri, 07 May 2021 05:47:12 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:2505) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lex4a-0008VK-Qc for qemu-devel@nongnu.org; Fri, 07 May 2021 05:47:11 -0400 Received: from dggeml757-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Fc58n3JNZzWgPn; Fri, 7 May 2021 17:42:49 +0800 (CST) Received: from dggema765-chm.china.huawei.com (10.1.198.207) by dggeml757-chm.china.huawei.com (10.1.199.137) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 7 May 2021 17:46:58 +0800 Received: from [10.174.185.210] (10.174.185.210) by dggema765-chm.china.huawei.com (10.1.198.207) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 7 May 2021 17:46:56 +0800 Subject: Re: [question] The source cannot recover, if the destination fails in the last round of live migration To: "Dr. David Alan Gilbert" References: <7d87a3b7-86c9-9248-59dc-e1612a00e7c3@huawei.com> From: Kunkun Jiang Message-ID: Date: Fri, 7 May 2021 17:46:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.185.210] X-ClientProxiedBy: dggeme707-chm.china.huawei.com (10.1.199.103) To dggema765-chm.china.huawei.com (10.1.198.207) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.187; envelope-from=jiangkunkun@huawei.com; helo=szxga01-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: David Edmondson , Juan Quintela , "open list:All patches CC here" , Peter Xu , Zenghui Yu , wanghaibin.wang@huawei.com, Keqian Zhu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Dave, On 2021/5/6 21:05, Dr. David Alan Gilbert wrote: > * Kunkun Jiang (jiangkunkun@huawei.com) wrote: >> Hi all, > Hi, > >> Recently I am learning about the part of live migration. >> I have a question about the last round. >> >> When the pending_size is less than the threshold, it will enter >> the last round and call migration_completion(). It will stop the >> source and sent the remaining dirty pages and devices' status >> information to the destination. The destination will load these >> information and start the VM. >> >> If there is an error at the destination at this time, it will exit >> directly, and the source will not be able to detect the error >> and recover. Because the source will not call >> migration_detect_error(). >> >> Is my understanding correct? >> Should the source wait the result of the last round of destination ? > Try setting the 'return-path' migration capability on both the source > and destination; I think it's that option will cause the destination to > send an OK/error at the end and the source to wait for it. Thank you for your reply! The 'return-path' migration capability solved my question. 😁 But why not set it as the default? In my opinion, it is a basic ability of live migration. We need it to judge whether the last round of the destination is successful in the way of 'precopy'. Looking forward to your reply. Thanks, Kunkun Jiang > Dave > >> Thanks, >> Kunkun Jiang >> >>