From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752770Ab1FKW6T (ORCPT ); Sat, 11 Jun 2011 18:58:19 -0400 Received: from shards.monkeyblade.net ([198.137.202.13]:49604 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752398Ab1FKW6R (ORCPT ); Sat, 11 Jun 2011 18:58:17 -0400 Date: Sat, 11 Jun 2011 15:58:02 -0700 (PDT) Message-Id: <20110611.155802.495936379311916892.davem@davemloft.net> To: mst@redhat.com Cc: jasowang@redhat.com, rusty@rustcorp.com.au, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, yvugenfi@redhat.com, kvm@vger.kernel.org, herbert@gondor.hengli.com.au Subject: Re: [PATCH] virtio_net: introduce VIRTIO_NET_HDR_F_DATA_VALID From: David Miller In-Reply-To: <20110610112828.GA21037@redhat.com> References: <1307703377-3798-1-git-send-email-jasowang@redhat.com> <20110610112828.GA21037@redhat.com> X-Mailer: Mew version 6.3 on Emacs 23.2 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (shards.monkeyblade.net [198.137.202.13]); Sat, 11 Jun 2011 15:58:03 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Michael S. Tsirkin" Date: Fri, 10 Jun 2011 14:28:28 +0300 > On Fri, Jun 10, 2011 at 06:56:17PM +0800, Jason Wang wrote: >> There's no need for the guest to validate the checksum if it have been >> validated by host nics. So this patch introduces a new flag - >> VIRTIO_NET_HDR_F_DATA_VALID which is used to bypass the checksum >> examing in guest. The backend (tap/macvtap) may set this flag when >> met skbs with CHECKSUM_UNNECESSARY to save cpu utilization. >> >> No feature negotiation is needed as old driver just ignore this flag. > > This wasn't required by the spec, but maybe it should be. > >> Iperf shows 12%-30% performance improvement for UDP traffic. For TCP, >> when gro is on no difference as it produces skb with partial >> checksum. But when gro is disabled, 20% or even higher improvement >> could be measured by netperf. >> >> Signed-off-by: Jason Wang > > > Acked-by: Michael S. Tsirkin Applied to net-next-2.6