From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55259) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bY1i1-00050H-MI for qemu-devel@nongnu.org; Thu, 11 Aug 2016 21:56:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bY1hx-0003fb-Gv for qemu-devel@nongnu.org; Thu, 11 Aug 2016 21:56:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57458) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bY1hx-0003eG-Av for qemu-devel@nongnu.org; Thu, 11 Aug 2016 21:56:25 -0400 References: <1470840390-29235-1-git-send-email-mst@redhat.com> <20160811134831.768a9c2e.cornelia.huck@de.ibm.com> From: Jason Wang Message-ID: <41e90683-abeb-d4c8-39c6-4df9f570a75b@redhat.com> Date: Fri, 12 Aug 2016 09:56:17 +0800 MIME-Version: 1.0 In-Reply-To: <20160811134831.768a9c2e.cornelia.huck@de.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2] virtio-net: allow increasing rx queue size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck , "Michael S. Tsirkin" Cc: Patrik Hermansson , qemu-devel@nongnu.org On 2016=E5=B9=B408=E6=9C=8811=E6=97=A5 19:48, Cornelia Huck wrote: > On Wed, 10 Aug 2016 17:47:16 +0300 > "Michael S. Tsirkin" wrote: > >> This allows increasing the rx queue size up to 1024: unlike with tx, >> guests don't put in huge S/G lists into RX so the risk of running into >> the max 1024 limitation due to some off-by-one seems small. >> >> It's helpful for users like OVS-DPDK which don't do any buffering on t= he >> host - 1K roughly matches 500 entries in tun + 256 in the current rx >> queue, which seems to work reasonably well. We could probably make do >> with ~750 entries but virtio spec limits us to powers of two. >> It might be a good idea to specify an s/g size limit in a future >> version. >> >> It also might be possible to make the queue size smaller down the road= , 64 >> seems like the minimal value which will still work (as guests seem to >> assume a queue full of 1.5K buffers is enough to process the largest >> incoming packet, which is ~64K). No one actually asked for this, and >> with virtio 1 guests can reduce ring size without need for host >> configuration, so don't bother with this for now. >> >> Cc: Cornelia Huck >> Cc: Jason Wang >> Suggested-by: Patrik Hermansson >> Signed-off-by: Michael S. Tsirkin >> --- >> >> changes from v1: >> add macros as suggested by Cornelia >> >> include/hw/virtio/virtio-net.h | 1 + >> hw/net/virtio-net.c | 26 +++++++++++++++++++++++++- >> 2 files changed, 26 insertions(+), 1 deletion(-) > Reviewed-by: Cornelia Huck > > > Queued in net-next (for 2.8) Thanks