From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <maxime.coquelin@redhat.com> Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id D29AB293C for <dev@dpdk.org>; Fri, 4 Nov 2016 12:40:05 +0100 (CET) Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3DEFE7F3EC; Fri, 4 Nov 2016 11:40:05 +0000 (UTC) Received: from [10.36.5.74] (vpn1-5-74.ams2.redhat.com [10.36.5.74]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA4BdxkE019528 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 4 Nov 2016 07:40:02 -0400 To: Yuanhan Liu <yuanhan.liu@linux.intel.com> References: <8F6C2BD409508844A0EFC19955BE09414E7D90C7@SHSMSX103.ccr.corp.intel.com> <88169067-290d-a7bb-ab2c-c9b8ec1b1ded@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7DA533@SHSMSX103.ccr.corp.intel.com> <c1899521-2dee-75a4-4723-a8cf851a18d1@redhat.com> <eb2dc51c-8ada-cca4-0a51-7c50fd25361e@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7DC40F@SHSMSX103.ccr.corp.intel.com> <17d285a9-818c-b060-8969-daccb052dc1f@redhat.com> <7e1c8953-db15-f377-cece-85cb7169bb17@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7DC5B6@SHSMSX103.ccr.corp.intel.com> <cf5e40da-0201-8c89-5314-96c87894da12@redhat.com> <20161104113628.GC16751@yliu-dev.sh.intel.com> Cc: "Wang, Zhihong" <zhihong.wang@intel.com>, "stephen@networkplumber.org" <stephen@networkplumber.org>, "Pierre Pfister (ppfister)" <ppfister@cisco.com>, "Xie, Huawei" <huawei.xie@intel.com>, "dev@dpdk.org" <dev@dpdk.org>, "vkaplans@redhat.com" <vkaplans@redhat.com>, "mst@redhat.com" <mst@redhat.com> From: Maxime Coquelin <maxime.coquelin@redhat.com> Message-ID: <961a0207-8a78-faf1-480b-5f09d19575c5@redhat.com> Date: Fri, 4 Nov 2016 12:39:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20161104113628.GC16751@yliu-dev.sh.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 04 Nov 2016 11:40:05 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors support to the TX path X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Fri, 04 Nov 2016 11:40:06 -0000 On 11/04/2016 12:36 PM, Yuanhan Liu wrote: > On Fri, Nov 04, 2016 at 12:22:47PM +0100, Maxime Coquelin wrote: >> >> >>>>>> Hi Maxime, >>>>>> >>>>>> I did a little more macswap test and found out more stuff here: >>>>> Thanks for doing more tests. >>>>> >>>>>> >>>>>> 1. I did loopback test on another HSW machine with the same H/W, >>>>>> and indirect_desc on and off seems have close perf >>>>>> >>>>>> 2. So I checked the gcc version: >>>>>> >>>>>> * Previous: gcc version 6.2.1 20160916 (Fedora 24) >>>>>> >>>>>> * New: gcc version 5.4.0 20160609 (Ubuntu 16.04.1 LTS) >>>>> >>>>> On my side, I tested with RHEL7.3: >>>>> - gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11) >>>>> >>>>> It certainly contains some backports from newer GCC versions. >>>>> >>>>>> >>>>>> On previous one indirect_desc has 20% drop >>>>>> >>>>>> 3. Then I compiled binary on Ubuntu and scp to Fedora, and as >>>>>> expected I got the same perf as on Ubuntu, and the perf gap >>>>>> disappeared, so gcc is definitely one factor here >>>>>> >>>>>> 4. Then I use the Ubuntu binary on Fedora for PVP test, then the >>>>>> perf gap comes back again and the same with the Fedora binary >>>>>> results, indirect_desc causes about 20% drop >>>>> >>>>> Let me know if I understand correctly: >>> >>> Yes, and it's hard to breakdown further at this time. >>> >>> Also we may need to check whether it's caused by certain NIC >>> model. Unfortunately I don't have the right setup right now. >>> >>>>> Loopback test with macswap: >>>>> - gcc version 6.2.1 : 20% perf drop >>>>> - gcc version 5.4.0 : No drop >>>>> >>>>> PVP test with macswap: >>>>> - gcc version 6.2.1 : 20% perf drop >>>>> - gcc version 5.4.0 : 20% perf drop >>>> >>>> I forgot to ask, did you recompile only host, or both host and guest >>>> testmpd's in your test? >> >>> Both. >> >> I recompiled testpmd on a Fedora 24 machine using GCC6: > > Have you built host DPDK with gcc6 as well? Yes, I use the same build based on GCC6 on both sides. > > --yliu > >> gcc (GCC) 6.1.1 20160621 (Red Hat 6.1.1-3) >> Testing loopback with macswap on my Haswell RHEL7.3 machine gives me the >> following results: >> - indirect on: 7.75Mpps >> - indirect off: 7.35Mpps >> >> Surprisingly, I get better results with indirect on my setup (I >> reproduced the tests multiple times). >> >> Do you have a document explaining the tuning/config you apply to both the >> host and the guest (isolation, HT, hugepage size, ...) in your >> setup? >> >> Regards, >> Maxime