From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754054AbdBVDiX (ORCPT ); Tue, 21 Feb 2017 22:38:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52818 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752599AbdBVDiQ (ORCPT ); Tue, 21 Feb 2017 22:38:16 -0500 Subject: Re: [PATCH net-next] virtio-net: switch to use build_skb() for small buffer To: "Michael S. Tsirkin" References: <1487666788-9658-1-git-send-email-jasowang@redhat.com> <20170221162849-mutt-send-email-mst@kernel.org> <35244d06-2d0d-3f2e-0cd1-43137988c869@redhat.com> <20170222050601-mutt-send-email-mst@kernel.org> <49577dad-3f6f-e6b3-4f93-2b919b066068@redhat.com> Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org From: Jason Wang Message-ID: <90ed2166-0e67-01ff-2c5e-ce7fbad56be2@redhat.com> Date: Wed, 22 Feb 2017 11:38:01 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <49577dad-3f6f-e6b3-4f93-2b919b066068@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 22 Feb 2017 03:38:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017年02月22日 11:17, Jason Wang wrote: > > > On 2017年02月22日 11:06, Michael S. Tsirkin wrote: >> On Wed, Feb 22, 2017 at 10:58:08AM +0800, Jason Wang wrote: >>> >>> On 2017年02月21日 22:37, Michael S. Tsirkin wrote: >>>> On Tue, Feb 21, 2017 at 04:46:28PM +0800, Jason Wang wrote: >>>>> This patch switch to use build_skb() for small buffer which can have >>>>> better performance for both TCP and XDP (since we can work at page >>>>> before skb creation). It also remove lots of XDP codes since both >>>>> mergeable and small buffer use page frag during refill now. >>>>> >>>>> Before | After >>>>> XDP_DROP(xdp1) 64B : 11.1Mpps | 14.4Mpps >>>>> >>>>> Tested with xdp1/xdp2/xdp_ip_tx_tunnel and netperf. >>>>> >>>>> Signed-off-by: Jason Wang >>>> Thanks! >>>> I had a similar patch for mergeable too, though it's trickier there >>>> as host has a lot of flexibility in sizing buffers. >>>> Looks like a good intermediate step to me. >>> Yes, I think it's more tricky for the case of mergeable buffer: >>> >>> 1) we need reserve NET_SKB_PAD + NET_IP_ALIGN for each buffer, this >>> will >>> break rx frag coalescing >>> 2) need tailroom for skb_shinfo, so it won't work for all size of >>> packet >>> >>> Thanks >> Have you seen my prototype? > > Not yet, please give me a pointer. FYI, I posted a prototype during EWMA discussion in 2013: https://lists.linuxfoundation.org/pipermail/virtualization/2013-October/025556.html