From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753491Ab0INQgC (ORCPT ); Tue, 14 Sep 2010 12:36:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33335 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752671Ab0INQf6 (ORCPT ); Tue, 14 Sep 2010 12:35:58 -0400 Date: Tue, 14 Sep 2010 18:29:52 +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: <20100914162952.GB13560@redhat.com> References: <1284410580.13351.10.camel@localhost.localdomain> <4C8F3C77.7010302@redhat.com> <1284476719.13351.35.camel@localhost.localdomain> <201009141721.13202.arnd@arndb.de> <20100914152231.GA13105@redhat.com> <1284480025.13351.49.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1284480025.13351.49.camel@localhost.localdomain> User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 14, 2010 at 09:00:25AM -0700, Shirley Ma wrote: > On Tue, 2010-09-14 at 17:22 +0200, Michael S. Tsirkin wrote: > > I would expect this to hurt performance significantly. > > We could do this for asynchronous requests only to avoid the > > slowdown. > > Is kiocb in sendmsg helpful here? It is not used now. > > Shirley Precisely. This is what the patch from Xin Xiaohui does. That code already seems to do most of what you are trying to do, right? The main thing missing seems to be macvtap integration, so that we can fall back on data copy if zero copy is unavailable? How hard would it be to basically link the mp and macvtap modules together to get us this functionality? Anyone? -- MST