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 9D8602C06 for ; Fri, 28 Oct 2016 02:50:13 +0200 (CEST) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP; 27 Oct 2016 17:50:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,406,1473145200"; d="scan'208";a="1051444685" Received: from fmsmsx106.amr.corp.intel.com ([10.18.124.204]) by orsmga001.jf.intel.com with ESMTP; 27 Oct 2016 17:50:12 -0700 Received: from fmsmsx116.amr.corp.intel.com (10.18.116.20) by FMSMSX106.amr.corp.intel.com (10.18.124.204) with Microsoft SMTP Server (TLS) id 14.3.248.2; Thu, 27 Oct 2016 17:49:58 -0700 Received: from shsmsx101.ccr.corp.intel.com (10.239.4.153) by fmsmsx116.amr.corp.intel.com (10.18.116.20) with Microsoft SMTP Server (TLS) id 14.3.248.2; Thu, 27 Oct 2016 17:49:57 -0700 Received: from shsmsx103.ccr.corp.intel.com ([169.254.4.139]) by SHSMSX101.ccr.corp.intel.com ([169.254.1.104]) with mapi id 14.03.0248.002; Fri, 28 Oct 2016 08:49:55 +0800 From: "Wang, Zhihong" To: Yuanhan Liu , Maxime Coquelin Thread-Topic: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors support to the TX path Thread-Index: AQHSJjLIgzIjeGrkS0+qEKh9oEoL36Cr/zyAgAAg9YCAAA7sgIAP4USA//+BDwCAABccgIAAAIiAgAADH4CAAXEIoA== Date: Fri, 28 Oct 2016 00:49:55 +0000 Message-ID: <8F6C2BD409508844A0EFC19955BE09414E7D90C7@SHSMSX103.ccr.corp.intel.com> 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> In-Reply-To: <20161027104621.GN16751@yliu-dev.sh.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 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: Fri, 28 Oct 2016 00:50:14 -0000 > -----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 suppor= t > to the TX path >=20 > 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=3Don and mrg=3Doff (--txqflags=3D0xf00, 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 t= o > > see if issue is reproducible like this. >=20 > 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. >=20 > > 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. >=20 > Makes sense. >=20 > --yliu > > > > Thanks, > > Maxime > > > > > > > > --yliu > > > > > >>Have you tried to pass indirect_desc=3Doff to qemu cmdline to see if = you > > >>recover the performance? > > >> > > >>Yuanhan, which platform did you use when you tested it with zero copy= ? > > >> > > >>> > > >>>I'm using RC2, and the CPU is Xeon E5-2699 v3 @ 2.30GHz. > > >>> > > >>>Could you please verify if this is true in your test? > > >>I'll try -rc1/-rc2 on my platform, and let you know. > > >> > > >>Thanks, > > >>Maxime > > >> > > >>> > > >>> > > >>>Thanks > > >>>Zhihong > > >>> > > >>>>-----Original Message----- > > >>>>From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] > > >>>>Sent: Monday, October 17, 2016 10:15 PM > > >>>>To: Yuanhan Liu > > >>>>Cc: Wang, Zhihong ; Xie, Huawei > > >>>>; dev@dpdk.org; vkaplans@redhat.com; > > >>>>mst@redhat.com; stephen@networkplumber.org > > >>>>Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors > support > > >>>>to the TX path > > >>>> > > >>>> > > >>>> > > >>>>On 10/17/2016 03:21 PM, Yuanhan Liu wrote: > > >>>>>On Mon, Oct 17, 2016 at 01:23:23PM +0200, Maxime Coquelin wrote: > > >>>>>>>On my side, I just setup 2 Windows 2016 VMs, and confirm the > issue. > > >>>>>>>I'll continue the investigation early next week. > > >>>>>> > > >>>>>>The root cause is identified. > > >>>>>>When INDIRECT_DESC feature is negotiated, Windows guest uses > indirect > > >>>>>>for both Tx and Rx descriptors, whereas Linux guests (Virtio PMD = & > > >>>>>>virtio-net kernel driver) use indirect only for Tx. > > >>>>>>I'll implement indirect support for the Rx path in vhost lib, but= the > > >>>>>>change will be too big for -rc release. > > >>>>>>I propose in the mean time to disable INDIRECT_DESC feature in > vhost > > >>>>>>lib, we can still enable it locally for testing. > > >>>>>> > > >>>>>>Yuanhan, is it ok for you? > > >>>>> > > >>>>>That's okay. > > >>>>I'll send a patch to disable it then. > > >>>> > > >>>>> > > >>>>>> > > >>>>>>>Has anyone already tested Windows guest with vhost-net, which > also > > >>>>has > > >>>>>>>indirect descs support? > > >>>>>> > > >>>>>>I tested and confirm it works with vhost-net. > > >>>>> > > >>>>>I'm a bit confused then. IIRC, vhost-net also doesn't support indi= rect > > >>>>>for Rx path, right? > > >>>> > > >>>>No, it does support it actually. > > >>>>I thought it didn't support too, I misread the Kernel implementatio= n of > > >>>>vhost-net and virtio-net. Acutally, virtio-net makes use of indirec= t > > >>>>in Rx path when mergeable buffers is disabled. > > >>>> > > >>>>The confusion certainly comes from me, sorry about that. > > >>>> > > >>>>Maxime