From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jakub Kicinski Subject: Re: [PATCH net-next V2 3/3] tap: XDP support Date: Fri, 11 Aug 2017 16:12:23 -0700 Message-ID: <20170811161223.6808008d@cakuba.netronome.com> References: <1502451678-17358-1-git-send-email-jasowang@redhat.com> <1502451678-17358-4-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Borkmann To: Jason Wang Return-path: In-Reply-To: <1502451678-17358-4-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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?