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 5E4FF568A for ; Thu, 27 Oct 2016 11:10:39 +0200 (CEST) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (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 C4FFE32B0C8; Thu, 27 Oct 2016 09:10:38 +0000 (UTC) Received: from [10.36.6.117] (vpn1-6-117.ams2.redhat.com [10.36.6.117]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u9R9AZAw030469 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 27 Oct 2016 05:10:36 -0400 To: "Wang, Zhihong" , Yuanhan Liu , "stephen@networkplumber.org" , "Pierre Pfister (ppfister)" 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> <20161017132121.GG16751@yliu-dev.sh.intel.com> <8F6C2BD409508844A0EFC19955BE09414E7D8BDF@SHSMSX103.ccr.corp.intel.com> From: Maxime Coquelin Message-ID: Date: Thu, 27 Oct 2016 11:10:34 +0200 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: <8F6C2BD409508844A0EFC19955BE09414E7D8BDF@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 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 27 Oct 2016 09:10:38 +0000 (UTC) Cc: "dev@dpdk.org" , "vkaplans@redhat.com" , "mst@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: Thu, 27 Oct 2016 09:10:39 -0000 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. 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 >> 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 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