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 1CB5211D9 for ; Wed, 2 Nov 2016 11:51:39 +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 83BEC61B8C; Wed, 2 Nov 2016 10:51:38 +0000 (UTC) Received: from [10.36.4.51] (vpn1-4-51.ams2.redhat.com [10.36.4.51]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA2ApYmh018435 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 2 Nov 2016 06:51:36 -0400 To: "Wang, Zhihong" , Yuanhan Liu References: <1474965769-24782-1-git-send-email-maxime.coquelin@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7CE6D1@SHSMSX103.ccr.corp.intel.com> <70cc3b89-d680-1519-add3-f38b228e65b5@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> From: Maxime Coquelin Message-ID: Date: Wed, 2 Nov 2016 11:51:34 +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: <8F6C2BD409508844A0EFC19955BE09414E7DA533@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 [10.5.110.39]); Wed, 02 Nov 2016 10:51:38 +0000 (UTC) Cc: "mst@redhat.com" , "dev@dpdk.org" , "vkaplans@redhat.com" 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: Wed, 02 Nov 2016 10:51:40 -0000 On 10/31/2016 11:01 AM, Wang, Zhihong wrote: > > >> -----Original Message----- >> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] >> Sent: Friday, October 28, 2016 3:42 PM >> To: Wang, Zhihong ; Yuanhan Liu >> >> Cc: stephen@networkplumber.org; Pierre Pfister (ppfister) >> ; Xie, Huawei ; dev@dpdk.org; >> vkaplans@redhat.com; mst@redhat.com >> Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors support >> to the TX path >> >> >> >> On 10/28/2016 02:49 AM, Wang, Zhihong wrote: >>> >>>>> -----Original Message----- >>>>> From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com] >>>>> Sent: Thursday, October 27, 2016 6:46 PM >>>>> To: Maxime Coquelin >>>>> Cc: Wang, Zhihong ; >>>>> stephen@networkplumber.org; Pierre Pfister (ppfister) >>>>> ; Xie, Huawei ; >> dev@dpdk.org; >>>>> vkaplans@redhat.com; mst@redhat.com >>>>> Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors >> support >>>>> to the TX path >>>>> >>>>> On Thu, Oct 27, 2016 at 12:35:11PM +0200, Maxime Coquelin wrote: >>>>>>> >>>>>>> >>>>>>> On 10/27/2016 12:33 PM, Yuanhan Liu wrote: >>>>>>>>> On Thu, Oct 27, 2016 at 11:10:34AM +0200, Maxime Coquelin >> wrote: >>>>>>>>>>> Hi Zhihong, >>>>>>>>>>> >>>>>>>>>>> On 10/27/2016 11:00 AM, Wang, Zhihong wrote: >>>>>>>>>>>>> Hi Maxime, >>>>>>>>>>>>> >>>>>>>>>>>>> Seems indirect desc feature is causing serious performance >>>>>>>>>>>>> degradation on Haswell platform, about 20% drop for both >>>>>>>>>>>>> mrg=on and mrg=off (--txqflags=0xf00, non-vector version), >>>>>>>>>>>>> both iofwd and macfwd. >>>>>>>>>>> I tested PVP (with macswap on guest) and Txonly/Rxonly on an >> Ivy >>>>> Bridge >>>>>>>>>>> platform, and didn't faced such a drop. >>>>>>>>> >>>>>>>>> I was actually wondering that may be the cause. I tested it with >>>>>>>>> my IvyBridge server as well, I saw no drop. >>>>>>>>> >>>>>>>>> Maybe you should find a similar platform (Haswell) and have a try? >>>>>>> Yes, that's why I asked Zhihong whether he could test Txonly in guest >> to >>>>>>> see if issue is reproducible like this. >>>>> >>>>> I have no Haswell box, otherwise I could do a quick test for you. IIRC, >>>>> he tried to disable the indirect_desc feature, then the performance >>>>> recovered. So, it's likely the indirect_desc is the culprit here. >>>>> >>>>>>> I will be easier for me to find an Haswell machine if it has not to be >>>>>>> connected back to back to and HW/SW packet generator. >>> In fact simple loopback test will also do, without pktgen. >>> >>> Start testpmd in both host and guest, and do "start" in one >>> and "start tx_first 32" in another. >>> >>> Perf drop is about 24% in my test. >>> >> >> Thanks, I never tried this test. >> I managed to find an Haswell platform (Intel(R) Xeon(R) CPU E5-2699 v3 >> @ 2.30GHz), and can reproduce the problem with the loop test you >> mention. I see a performance drop about 10% (8.94Mpps/8.08Mpps). >> Out of curiosity, what are the numbers you get with your setup? > > Hi Maxime, > > Let's align our test case to RC2, mrg=on, loopback, on Haswell. > My results below: > 1. indirect=1: 5.26 Mpps > 2. indirect=0: 6.54 Mpps > > It's about 24% drop. OK, so on my side, same setup on Haswell: 1. indirect=1: 7.44 Mpps 2. indirect=0: 8.18 Mpps Still 10% drop in my case with mrg=on. The strange thing with both of our figures is that this is below from what I obtain with my SandyBridge machine. The SB cpu freq is 4% higher, but that doesn't explain the gap between the measurements. I'm continuing the investigations on my side. Maybe we should fix a deadline, and decide do disable indirect in Virtio PMD if root cause not identified/fixed at some point? Yuanhan, what do you think? Regards, Maxime