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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 47825C433DF for ; Wed, 10 Jun 2020 14:43:51 +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 1BC3D20734 for ; Wed, 10 Jun 2020 14:43:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1BC3D20734 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=openvz.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37974 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jj1xG-0002go-D9 for qemu-devel@archiver.kernel.org; Wed, 10 Jun 2020 10:43:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57624) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj1v7-0007wu-KD; Wed, 10 Jun 2020 10:41:37 -0400 Received: from relay.sw.ru ([185.231.240.75]:60326 helo=relay3.sw.ru) by eggs.gnu.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jj1v6-0001WN-HX; Wed, 10 Jun 2020 10:41:37 -0400 Received: from [192.168.15.9] (helo=iris.lishka.ru) by relay3.sw.ru with esmtp (Exim 4.93) (envelope-from ) id 1jj1v0-0004Xb-7u; Wed, 10 Jun 2020 17:41:30 +0300 From: "Denis V. Lunev" To: qemu-block@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH 0/2] qcow2: seriously improve savevm performance Date: Wed, 10 Jun 2020 17:41:27 +0300 Message-Id: <20200610144129.27659-1-den@openvz.org> X-Mailer: git-send-email 2.17.1 Received-SPF: pass client-ip=185.231.240.75; envelope-from=den@openvz.org; helo=relay3.sw.ru X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/10 10:41:32 X-ACL-Warn: Detected OS = Linux 3.11 and newer X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: Kevin Wolf , "Denis V . Lunev" , Vladimir Sementsov-Ogievskiy , Denis Plotnikov , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This series do standard basic things: - it creates intermediate buffer for all writes from QEMU migration code to QCOW2 image, - this buffer is sent to disk asynchronously, allowing several writes to run in parallel. In general, migration code is fantastically inefficent (by observation), buffers are not aligned and sent with arbitrary pieces, a lot of time less than 100 bytes at a chunk, which results in read-modify-write operations with non-cached operations. It should also be noted that all operations are performed into unallocated image blocks, which also suffer due to partial writes to such new clusters. This patch series is an implementation of idea discussed in the RFC posted by Denis https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg01925.html Results with this series over NVME are better than original code original rfc this cached: 1.79s 2.38s 1.27s non-cached: 3.29s 1.31s 0.81s Signed-off-by: Denis V. Lunev CC: Kevin Wolf CC: Max Reitz CC: Vladimir Sementsov-Ogievskiy CC: Denis Plotnikov