From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 2219AFFA for ; Fri, 4 Nov 2016 12:35:37 +0100 (CET) Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP; 04 Nov 2016 04:35:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,443,1473145200"; d="scan'208";a="27500033" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162]) by orsmga005.jf.intel.com with ESMTP; 04 Nov 2016 04:35:35 -0700 Date: Fri, 4 Nov 2016 19:36:28 +0800 From: Yuanhan Liu To: Maxime Coquelin Cc: "Wang, Zhihong" , "stephen@networkplumber.org" , "Pierre Pfister (ppfister)" , "Xie, Huawei" , "dev@dpdk.org" , "vkaplans@redhat.com" , "mst@redhat.com" Message-ID: <20161104113628.GC16751@yliu-dev.sh.intel.com> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) 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 11:35:38 -0000 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? --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