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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 4E70AC4363D for ; Fri, 25 Sep 2020 12:29:39 +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 C934821D7A for ; Fri, 25 Sep 2020 12:29:38 +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="IJO1TShx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C934821D7A 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]:42108 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLmr3-00038D-IY for qemu-devel@archiver.kernel.org; Fri, 25 Sep 2020 08:29:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39158) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLmZm-00019x-9h for qemu-devel@nongnu.org; Fri, 25 Sep 2020 08:11:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30295) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kLmZj-0004u1-Tq for qemu-devel@nongnu.org; Fri, 25 Sep 2020 08:11:45 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601035903; 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: in-reply-to:in-reply-to:references:references; bh=y+gySHXFPtcVMWGDh75/zYmsLP/gVPgTdBrVe3bE91U=; b=IJO1TShx4A2/Uerfta5Cj57DcjBt4hPp0IE7R4e8/vhkVqs4XduWs8Nk14W3tRVG+IgcWd 4OGx+yOruwDuzaMffxg3+9Q1fyshvF2TsK3ONBgCCVVYmHmJ9qFm4EcCkwXYWMUh4QpZFx 0I4axCOne20Do3rDX2iZdxdze7/VvWU= 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-287-Xed2SRbdMT-MUG6olyH2tQ-1; Fri, 25 Sep 2020 08:11:39 -0400 X-MC-Unique: Xed2SRbdMT-MUG6olyH2tQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7DDC88030CC; Fri, 25 Sep 2020 12:11:38 +0000 (UTC) Received: from work-vm (ovpn-114-177.ams2.redhat.com [10.36.114.177]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0DCA955761; Fri, 25 Sep 2020 12:11:29 +0000 (UTC) Date: Fri, 25 Sep 2020 13:11:27 +0100 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: tools/virtiofs: Multi threading seems to hurt performance Message-ID: <20200925121127.GI2873@work-vm> References: <20200918213436.GA3520@redhat.com> <20200921153243.GK3221@work-vm> <20200922102531.GA2837@work-vm> <20200922174733.GD57620@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200922174733.GD57620@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/25 02:48:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, 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=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: jose.carlos.venegas.munoz@intel.com, qemu-devel@nongnu.org, cdupontd@redhat.com, virtio-fs-list , Stefan Hajnoczi , archana.m.shinde@intel.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > On Tue, Sep 22, 2020 at 11:25:31AM +0100, Dr. David Alan Gilbert wrote: > > * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote: > > > Hi, > > > I've been doing some of my own perf tests and I think I agree > > > about the thread pool size; my test is a kernel build > > > and I've tried a bunch of different options. > > > > > > My config: > > > Host: 16 core AMD EPYC (32 thread), 128G RAM, > > > 5.9.0-rc4 kernel, rhel 8.2ish userspace. > > > 5.1.0 qemu/virtiofsd built from git. > > > Guest: Fedora 32 from cloud image with just enough extra installed for > > > a kernel build. > > > > > > git cloned and checkout v5.8 of Linux into /dev/shm/linux on the host > > > fresh before each test. Then log into the guest, make defconfig, > > > time make -j 16 bzImage, make clean; time make -j 16 bzImage > > > The numbers below are the 'real' time in the guest from the initial make > > > (the subsequent makes dont vary much) > > > > > > Below are the detauls of what each of these means, but here are the > > > numbers first > > > > > > virtiofsdefault 4m0.978s > > > 9pdefault 9m41.660s > > > virtiofscache=none 10m29.700s > > > 9pmmappass 9m30.047s > > > 9pmbigmsize 12m4.208s > > > 9pmsecnone 9m21.363s > > > virtiofscache=noneT1 7m17.494s > > > virtiofsdefaultT1 3m43.326s > > > > > > So the winner there by far is the 'virtiofsdefaultT1' - that's > > > the default virtiofs settings, but with --thread-pool-size=1 - so > > > yes it gives a small benefit. > > > But interestingly the cache=none virtiofs performance is pretty bad, > > > but thread-pool-size=1 on that makes a BIG improvement. > > > > Here are fio runs that Vivek asked me to run in my same environment > > (there are some 0's in some of the mmap cases, and I've not investigated > > why yet). > > cache=none does not allow mmap in case of virtiofs. That's when you > are seeing 0. > > >virtiofs is looking good here in I think all of the cases; > > there's some division over which cinfig; cache=none > > seems faster in some cases which surprises me. > > I know cache=none is faster in case of write workloads. It forces > direct write where we don't call file_remove_privs(). While cache=auto > goes through file_remove_privs() and that adds a GETXATTR request to > every WRITE request. Can you point me to how cache=auto causes the file_remove_privs? Dave > Vivek -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK