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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C6750C4338F for ; Thu, 19 Aug 2021 18:03:30 +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 5E73D6044F for ; Thu, 19 Aug 2021 18:03:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5E73D6044F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:45926 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mGmO1-00032Q-G7 for qemu-devel@archiver.kernel.org; Thu, 19 Aug 2021 14:03:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49166) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mGmNJ-0002Fy-3Q for qemu-devel@nongnu.org; Thu, 19 Aug 2021 14:02:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:57367) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mGmNH-0000UD-AS for qemu-devel@nongnu.org; Thu, 19 Aug 2021 14:02:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629396162; 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=x6nRK6yJxzEMS680/NqI4khJuTT+j5SperRoHXwD9Uw=; b=ddyD5PkkDA7TFLW24KeQFrfAAHfSZL3KBUyDfaior5N00jRFKPPmKaenFfcFo1y5MQrodp HQiITDBXuq8WDb3Vqt+S8IjvpiOFmhVtSYfuQlmIdAuub4no3Hkhw5Py0obvZwzKCRgpgE qaICCZDh60klcpuZB0O0A1t99AofPOQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-40-SCDoEkQKNZuAIoXLqctMiw-1; Thu, 19 Aug 2021 14:02:41 -0400 X-MC-Unique: SCDoEkQKNZuAIoXLqctMiw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D81CF6D4E1; Thu, 19 Aug 2021 18:02:39 +0000 (UTC) Received: from redhat.com (ovpn-114-146.phx2.redhat.com [10.3.114.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E335C18B42; Thu, 19 Aug 2021 18:02:31 +0000 (UTC) Date: Thu, 19 Aug 2021 13:02:30 -0500 From: Eric Blake To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH 3/3] qcow2: handle_dependencies(): relax conflict detection Message-ID: <20210819180230.eouxyi3j2754weyf@redhat.com> References: <20210724133846.64614-1-vsementsov@virtuozzo.com> <20210724133846.64614-4-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20210724133846.64614-4-vsementsov@virtuozzo.com> User-Agent: NeoMutt/20210205-732-28786f X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, 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: kwolf@redhat.com, den@openvz.org, qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, Jul 24, 2021 at 04:38:46PM +0300, Vladimir Sementsov-Ogievskiy wrote: > There is no conflict and no dependency if we have parallel writes to > different subclusters of one cluster when cluster itself is already when the cluster itself > allocated. So, relax extra dependency. > > Measure performance: > First, prepare build/qemu-img-old and build/qemu-img-new images. > > cd scripts/simplebench > ./img_bench_templater.py > > Paste the following to stdin of running script: > > qemu_img=../../build/qemu-img-{old|new} > $qemu_img create -f qcow2 -o extended_l2=on /ssd/x.qcow2 1G > $qemu_img bench -c 100000 -d 8 [-s 2K|-s 2K -o 512|-s $((1024*2+512))] \ > -w -t none -n /ssd/x.qcow2 > > The result: > > All results are in seconds > > ------------------ --------- --------- > old new > -s 2K 6.7 ± 15% 6.2 ± 12% > -7% > -s 2K -o 512 13 ± 3% 11 ± 5% > -16% > -s $((1024*2+512)) 9.5 ± 4% 8.4 > -12% > ------------------ --------- --------- Cool improvement. > > So small writes are more independent now and that helps to keep deeper > io queue which improves performance. > > 271 iotest output becomes racy for three allocation in one cluster. > Second and third writes may finish in different order. Second and > third requests don't depend on each other any more. Still they both > depend on first request anyway. Keep only one for consistent output. Interesting fallout. Yes, it looks like the test is still robust enough without the extra request. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block/qcow2-cluster.c | 11 +++++++++++ > tests/qemu-iotests/271 | 4 +--- > tests/qemu-iotests/271.out | 2 -- > 3 files changed, 12 insertions(+), 5 deletions(-) Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org