From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753486Ab0I2PUh (ORCPT ); Wed, 29 Sep 2010 11:20:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27662 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750984Ab0I2PUf (ORCPT ); Wed, 29 Sep 2010 11:20:35 -0400 Date: Wed, 29 Sep 2010 17:14:15 +0200 From: "Michael S. Tsirkin" To: Shirley Ma Cc: Arnd Bergmann , Avi Kivity , "Xin, Xiaohui" , David Miller , netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 2/2] macvtap: TX zero copy between guest and host kernel Message-ID: <20100929151415.GA27041@redhat.com> References: <1284483745.13351.71.camel@localhost.localdomain> <20100914182707.GB15549@redhat.com> <1284490143.13351.82.camel@localhost.localdomain> <20100914190156.GA16037@redhat.com> <1284492983.13351.95.camel@localhost.localdomain> <20100915051241.GA25340@redhat.com> <1284531675.24603.259.camel@localhost.localdomain> <20100915101000.GB28016@redhat.com> <1284562354.2573.12.camel@localhost.localdomain> <1285730669.31343.7.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1285730669.31343.7.camel@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 28, 2010 at 08:24:29PM -0700, Shirley Ma wrote: > Hello Michael, > > On Wed, 2010-09-15 at 07:52 -0700, Shirley Ma wrote: > > > > Don't you think once I address vhost_add_used_and_signal update > > > > issue, it is a simple and complete patch for macvtap TX zero copy? > > > > > > > > Thanks > > > > Shirley > > > > > > I like the fact that the patch is simple. Unfortunately > > > I suspect it'll stop being simple by the time it's complete :) > > > > I can make a try. :) > > I compared several approaches for addressing the issue being raised here > on how/when to update vhost_add_used_and_signal. The simple approach I > have found is: > > 1. Adding completion field in struct virtqueue; > 2. when it is a zero copy packet, put vhost thread wait for completion > to update vhost_add_used_and_signal; > 3. passing vq from vhost to macvtap as skb destruct_arg; > 4. when skb is freed for the last reference, signal vq completion > > The test results show same performance as the original patch. How do you > think? If it sounds good to you. I will resubmit this reversion patch. > The patch still keeps as simple as it was before. :) > > Thanks > Shirley I guess I just don't understand what your patch does. If you send it, I can take a look. -- MST