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=-6.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F0722C433E2 for ; Tue, 15 Sep 2020 08:57:26 +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 857302078D for ; Tue, 15 Sep 2020 08:57:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PZOkbdnt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 857302078D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46134 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kI6mD-0002CW-JJ for qemu-devel@archiver.kernel.org; Tue, 15 Sep 2020 04:57:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57822) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kI6ki-0001eS-Hj for qemu-devel@nongnu.org; Tue, 15 Sep 2020 04:55:52 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:58644) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kI6kc-0007Zt-7Z for qemu-devel@nongnu.org; Tue, 15 Sep 2020 04:55:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600160144; 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=SBQ1LTwfHgooJZ4henluDSAV84+F+Bz0lmuWkH4fzGQ=; b=PZOkbdntKydxDj0/dIrEjZ5l2LnbbnEUzmxC6Y5TtImis0tZ4hR0KK+HmM2+o1Fvp+kgVK CJn++5JZJ4RGbQGetDq6AjNJzrEiuc1cOn4rP3GjjGicV6WTPvzA+CQGq25+5gmt70G4sz FDAv14k6iJbn+dXl3bovOuItSMlrIF4= Received: from mail-ot1-f69.google.com (mail-ot1-f69.google.com [209.85.210.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-44-P-IbdzD_OyWK6VxfabPr8Q-1; Tue, 15 Sep 2020 04:55:36 -0400 X-MC-Unique: P-IbdzD_OyWK6VxfabPr8Q-1 Received: by mail-ot1-f69.google.com with SMTP id s3so821421otp.18 for ; Tue, 15 Sep 2020 01:55:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=SBQ1LTwfHgooJZ4henluDSAV84+F+Bz0lmuWkH4fzGQ=; b=peE/RLe4CVjzOgTVl9pRWZFgOCJfKGpgZEQY7svxiZ1ZJv7hlKNzsEvL9v1dMKgbd2 1v09fDEpfsQ/0E0P41lLcv/Y9z6+KUSFPuNZ25qwDVsl0g81nT1JPJWh1/7d3SM5UvfA 9q1kIqUnH1JwsK8IZ0Xvn3viYisEJ3xTEKuVHKlKbUnG5EV3kfsHRngS9ufTENvuRrg7 OvXQAMBWiABvHsp88cDaFJZqQm8u4RcxiOsFnWar2SWmFppWtOyKIKgoG6oD7s9DtUwi Mki87bvYs70ciJhvUGzQsq7hMSNcQCIkVPOIAAifU0n+37Ns+Wm5ZmPL/M6FARkgeJXC 2UtA== X-Gm-Message-State: AOAM533850cCovu5BrKO3FCoJDEQ2lbidJYGDcVkDiNszeh+SfjjCYAm JtHlT00LPMrXbNnyojtkvaoI37hutXCa18Ppik6i0f3tHu5ubdjcZS4TCU2YFOHyVyP/gbRAR6f DZfaDaolqa3n+lAqXdYFR9rXvyeK+wMU= X-Received: by 2002:a4a:bd90:: with SMTP id k16mr13513398oop.16.1600160134806; Tue, 15 Sep 2020 01:55:34 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx2tu7cm2QgW6WddRfLIN+ghpoVQpBV5dOSyZ2hq0lhiwkuMa5kLzl15xPeyS3h6eAKfCFBPPHOapLc5P5LRFw= X-Received: by 2002:a4a:bd90:: with SMTP id k16mr13513388oop.16.1600160134504; Tue, 15 Sep 2020 01:55:34 -0700 (PDT) MIME-Version: 1.0 References: <20200831140127.657134-1-nsoffer@redhat.com> <20200831140127.657134-3-nsoffer@redhat.com> <20200914173201.GR1252186@redhat.com> In-Reply-To: <20200914173201.GR1252186@redhat.com> From: Nir Soffer Date: Tue, 15 Sep 2020 11:55:18 +0300 Message-ID: Subject: Re: [PATCH 2/2] block: file-posix: Replace posix_fallocate with fallocate To: =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=nsoffer@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=63.128.21.124; envelope-from=nsoffer@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/15 02:23:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -38 X-Spam_score: -3.9 X-Spam_bar: --- X-Spam_report: (-3.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.792, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Kevin Wolf , Nir Soffer , qemu-block , Markus Armbruster , QEMU Developers , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Sep 14, 2020 at 8:32 PM Daniel P. Berrang=C3=A9 wrote: > > On Mon, Aug 31, 2020 at 05:01:27PM +0300, Nir Soffer wrote: > > If fallocate() is not supported, posix_fallocate() falls back to > > inefficient allocation, writing one byte for every 4k bytes[1]. This is > > very slow compared with writing zeros. In oVirt we measured ~400% > > improvement in allocation time when replacing posix_fallocate() with > > manually writing zeroes[2]. > > > > We also know that posix_fallocated() does not work well when using OFD > > locks[3]. We don't know the reason yet for this issue yet. > > > > Change preallocate_falloc() to use fallocate() instead of > > posix_falloate(), and fall back to full preallocation if not supported. > > > > Here are quick test results with this change. > > > > Before (qemu-img-5.1.0-2.fc32.x86_64): > > > > $ time qemu-img create -f raw -o preallocation=3Dfalloc /tmp/nfs3/test.= raw 6g > > Formatting '/tmp/nfs3/test.raw', fmt=3Draw size=3D6442450944 preallocat= ion=3Dfalloc > > > > real 0m42.100s > > user 0m0.602s > > sys 0m4.137s > > > > NFS stats: > > calls retrans authrefrsh write > > 1571583 0 1572205 1571321 > > > > After: > > > > $ time ./qemu-img create -f raw -o preallocation=3Dfalloc /tmp/nfs3/tes= t.raw 6g > > Formatting '/tmp/nfs3/test.raw', fmt=3Draw size=3D6442450944 preallocat= ion=3Dfalloc > > > > real 0m15.551s > > user 0m0.070s > > sys 0m2.623s > > > > NFS stats: > > calls retrans authrefrsh write > > 24620 0 24624 24567 > > > > [1] https://code.woboq.org/userspace/glibc/sysdeps/posix/posix_fallocat= e.c.html#96 > > [2] https://bugzilla.redhat.com/1850267#c25 > > [3] https://bugzilla.redhat.com/1851097 > > This bug appears to be private to RH employees only, so rather than link > to it, please summarize any important facts in it for benefit of nonn-RH > QEMU contributors. Thanks, I missed that detail when linking to the bug. The bug is public now= . > > Signed-off-by: Nir Soffer > > --- > > block/file-posix.c | 32 +++++++++----------------- > > docs/system/qemu-block-drivers.rst.inc | 11 +++++---- > > docs/tools/qemu-img.rst | 11 +++++---- > > qapi/block-core.json | 4 ++-- > > 4 files changed, 25 insertions(+), 33 deletions(-) > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| > |: https://libvirt.org -o- https://fstop138.berrange.c= om :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :| >