From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 39B692BE3 for ; Fri, 4 Nov 2016 12:22:53 +0100 (CET) Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (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 969E9C04B95D; Fri, 4 Nov 2016 11:22:52 +0000 (UTC) Received: from [10.36.5.74] (vpn1-5-74.ams2.redhat.com [10.36.5.74]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA4BMluL004571 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 4 Nov 2016 07:22:49 -0400 To: "Wang, Zhihong" , Yuanhan Liu References: <1474965769-24782-1-git-send-email-maxime.coquelin@redhat.com> <20161017132121.GG16751@yliu-dev.sh.intel.com> <8F6C2BD409508844A0EFC19955BE09414E7D8BDF@SHSMSX103.ccr.corp.intel.com> <20161027103317.GM16751@yliu-dev.sh.intel.com> <0ba8f8c9-2174-b3c1-4f07-f6911bffa6cd@redhat.com> <20161027104621.GN16751@yliu-dev.sh.intel.com> <8F6C2BD409508844A0EFC19955BE09414E7D90C7@SHSMSX103.ccr.corp.intel.com> <88169067-290d-a7bb-ab2c-c9b8ec1b1ded@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7DA533@SHSMSX103.ccr.corp.intel.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> Cc: "stephen@networkplumber.org" , "Pierre Pfister (ppfister)" , "Xie, Huawei" , "dev@dpdk.org" , "vkaplans@redhat.com" , "mst@redhat.com" From: Maxime Coquelin Message-ID: Date: Fri, 4 Nov 2016 12:22:47 +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: <8F6C2BD409508844A0EFC19955BE09414E7DC5B6@SHSMSX103.ccr.corp.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Fri, 04 Nov 2016 11:22:52 +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 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Nov 2016 11:22:54 -0000 >>>> 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: 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