From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <yuanhan.liu@linux.intel.com> Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id 9FED72E41 for <dev@dpdk.org>; Thu, 27 Oct 2016 12:32:27 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP; 27 Oct 2016 03:32:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,404,1473145200"; d="scan'208";a="778475898" Received: from yliu-dev.sh.intel.com (HELO yliu-dev) ([10.239.67.162]) by FMSMGA003.fm.intel.com with ESMTP; 27 Oct 2016 03:32:26 -0700 Date: Thu, 27 Oct 2016 18:33:17 +0800 From: Yuanhan Liu <yuanhan.liu@linux.intel.com> To: Maxime Coquelin <maxime.coquelin@redhat.com> Message-ID: <20161027103317.GM16751@yliu-dev.sh.intel.com> References: <1474619303-16709-1-git-send-email-maxime.coquelin@redhat.com> <1474965769-24782-1-git-send-email-maxime.coquelin@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7CE6D1@SHSMSX103.ccr.corp.intel.com> <70cc3b89-d680-1519-add3-f38b228e65b5@redhat.com> <f1129452-af2e-b8ae-600c-492182bec06d@redhat.com> <20161017132121.GG16751@yliu-dev.sh.intel.com> <db6244b6-37ed-e26e-3c93-420818efa8ae@redhat.com> <8F6C2BD409508844A0EFC19955BE09414E7D8BDF@SHSMSX103.ccr.corp.intel.com> <a7ea1206-86ab-911c-a6b4-718e4dd5c1f2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <a7ea1206-86ab-911c-a6b4-718e4dd5c1f2@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "mst@redhat.com" <mst@redhat.com>, "dev@dpdk.org" <dev@dpdk.org>, "vkaplans@redhat.com" <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 <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: Thu, 27 Oct 2016 10:32:28 -0000 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? --yliu > Have you tried to pass indirect_desc=off 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 <yuanhan.liu@linux.intel.com> > >>Cc: Wang, Zhihong <zhihong.wang@intel.com>; Xie, Huawei > >><huawei.xie@intel.com>; 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 indirect > >>>for Rx path, right? > >> > >>No, it does support it actually. > >>I thought it didn't support too, I misread the Kernel implementation of > >>vhost-net and virtio-net. Acutally, virtio-net makes use of indirect > >>in Rx path when mergeable buffers is disabled. > >> > >>The confusion certainly comes from me, sorry about that. > >> > >>Maxime