From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next V2 3/3] tap: XDP support Date: Sat, 12 Aug 2017 10:48:49 +0800 Message-ID: <8876b3d1-699c-d033-e855-34b24a709c81@redhat.com> References: <1502451678-17358-1-git-send-email-jasowang@redhat.com> <1502451678-17358-4-git-send-email-jasowang@redhat.com> <20170811161223.6808008d@cakuba.netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Borkmann To: Jakub Kicinski Return-path: In-Reply-To: <20170811161223.6808008d@cakuba.netronome.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2017年08月12日 07:12, Jakub Kicinski wrote: > On Fri, 11 Aug 2017 19:41:18 +0800, Jason Wang wrote: >> This patch tries to implement XDP for tun. The implementation was >> split into two parts: >> >> - fast path: small and no gso packet. We try to do XDP at page level >> before build_skb(). For XDP_TX, since creating/destroying queues >> were completely under control of userspace, it was implemented >> through generic XDP helper after skb has been built. This could be >> optimized in the future. >> - slow path: big or gso packet. We try to do it after skb was created >> through generic XDP helpers. >> >> Test were done through pktgen with small packets. >> >> xdp1 test shows ~41.1% improvement: >> >> Before: ~1.7Mpps >> After: ~2.3Mpps >> >> xdp_redirect to ixgbe shows ~60% improvement: >> >> Before: ~0.8Mpps >> After: ~1.38Mpps >> >> Suggested-by: Michael S. Tsirkin >> Signed-off-by: Jason Wang > Looks OK to me now :) > > Out of curiosity, you say the build_skb() is for "small packets", and it > seems you are always reserving the 256B regardless of XDP being > installed. Does this have no performance impact on non-XDP case? Have a test, only less than 1% were noticed which I think could be ignored. Thanks