From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Coquelin Subject: Re: [PATCH v4] vhost: Add indirect descriptors support to the TX path Date: Mon, 17 Oct 2016 16:14:45 +0200 Message-ID: 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> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "Wang, Zhihong" , "Xie, Huawei" , "dev@dpdk.org" , "vkaplans@redhat.com" , "mst@redhat.com" , "stephen@networkplumber.org" To: Yuanhan Liu Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id B3BAA5934 for ; Mon, 17 Oct 2016 16:14:49 +0200 (CEST) In-Reply-To: <20161017132121.GG16751@yliu-dev.sh.intel.com> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 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