From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40418) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dKcwB-00057P-Jd for qemu-devel@nongnu.org; Mon, 12 Jun 2017 23:56:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dKcw8-0002Up-CE for qemu-devel@nongnu.org; Mon, 12 Jun 2017 23:56:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39274) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dKcw8-0002UZ-6E for qemu-devel@nongnu.org; Mon, 12 Jun 2017 23:56:12 -0400 References: <1496653049-44530-1-git-send-email-wei.w.wang@intel.com> <20170605182514-mutt-send-email-mst@kernel.org> <5937511D.5070205@intel.com> <20170608220006-mutt-send-email-mst@kernel.org> <593A0F47.5080806@intel.com> <593E5F46.5080704@intel.com> <20170612234035-mutt-send-email-mst@kernel.org> <593F57C0.9080701@intel.com> <4639c51b-32a6-3528-2ed6-c5f6296b6300@redhat.com> <593F6133.9050804@intel.com> From: Jason Wang Message-ID: <65faf3f9-a839-0b04-c740-6b2a60a51cf6@redhat.com> Date: Tue, 13 Jun 2017 11:55:59 +0800 MIME-Version: 1.0 In-Reply-To: <593F6133.9050804@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [virtio-dev] Re: [PATCH v1] virtio-net: enable configurable tx queue size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wei Wang , "Michael S. Tsirkin" Cc: virtio-dev@lists.oasis-open.org, stefanha@gmail.com, qemu-devel@nongnu.org, jan.scheurich@ericsson.com, armbru@redhat.com, marcandre.lureau@gmail.com, pbonzini@redhat.com On 2017=E5=B9=B406=E6=9C=8813=E6=97=A5 11:51, Wei Wang wrote: > On 06/13/2017 11:19 AM, Jason Wang wrote: >> >> >> On 2017=E5=B9=B406=E6=9C=8813=E6=97=A5 11:10, Wei Wang wrote: >>> On 06/13/2017 04:43 AM, Michael S. Tsirkin wrote: >>>> On Mon, Jun 12, 2017 at 05:30:46PM +0800, Wei Wang wrote: >>>>> Ping for comments, thanks. >>>> This was only posted a week ago, might be a bit too short for some >>>> people. >>> OK, sorry for the push. >>>> A couple of weeks is more reasonable before you ping. Also, I >>>> sent a bunch of comments on Thu, 8 Jun 2017. You should probably >>>> address these. >>>> >>> I responded to the comments. The main question is that I'm not sure >>> why we need the vhost backend to support VIRTIO_F_MAX_CHAIN_SIZE. >>> IMHO, that should be a feature proposed to solve the possible issue >>> caused by the QEMU implemented backend. >> >> The issue is what if there's a mismatch of max #sgs between qemu and=20 >> vhost? >> > > When the vhost backend is used, QEMU is not involved in the data path.=20 > The vhost backend > directly gets what is offered by the guest from the vq. Why would=20 > there be a mismatch of > max #sgs between QEMU and vhost, and what is the QEMU side max #sgs=20 > used for? Thanks. You need query the backend max #sgs in this case at least. no? If not=20 how do you know the value is supported by the backend? Thanks > > Best, > Wei > >