Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758139Ab0HDCNK (ORCPT ); Tue, 3 Aug 2010 22:13:10 -0400 Received: from mga14.intel.com ([143.182.124.37]:22981 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756860Ab0HDCNI convert rfc822-to-8bit (ORCPT ); Tue, 3 Aug 2010 22:13:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.55,313,1278313200"; d="scan'208";a="307912746" From: "Dong, Eddie" To: Arnd Bergmann , Shirley Ma CC: "Xin, Xiaohui" , "netdev@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "mst@redhat.com" , "mingo@elte.hu" , "davem@davemloft.net" , "herbert@gondor.apana.org.au" , "jdike@linux.intel.com" , "Dong, Eddie" , "Dong, Eddie" Date: Wed, 4 Aug 2010 10:06:05 +0800 Subject: RE: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM virtio-net. Thread-Topic: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM virtio-net. Thread-Index: AcswkzBWXHYtzPpKS8q3axBKY9jN0wC5XJ9A Message-ID: <1A42CE6F5F474C41B63392A5F80372B228FCE7B1@shsmsx501.ccr.corp.intel.com> References: <1280402088-5849-1-git-send-email-xiaohui.xin@intel.com> <1280505112.9058.31.camel@localhost.localdomain> <201007311130.17000.arnd@arndb.de> In-Reply-To: <201007311130.17000.arnd@arndb.de> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1550 Lines: 31 Arnd Bergmann wrote: > On Friday 30 July 2010 17:51:52 Shirley Ma wrote: >> On Fri, 2010-07-30 at 16:53 +0800, Xin, Xiaohui wrote: >>>> Since vhost-net already supports macvtap/tun backends, do you think >>>> whether it's better to implement zero copy in macvtap/tun than >>>> inducing a new media passthrough device here? >>>> >>> >>> I'm not sure if there will be more duplicated code in the kernel. >> >> I think it should be less duplicated code in the kernel if we use >> macvtap to support what media passthrough driver here. Since macvtap >> has support virtio_net head and offloading already, the only missing >> func is zero copy. Also QEMU supports macvtap, we just need add a >> zero copy flag in option. > > Yes, I fully agree and that was one of the intended directions for > macvtap to start with. Thank you so much for following up on that, > I've long been planning to work on macvtap zero-copy myself but it's > now lower on my priorities, so it's good to hear that you made > progress on it, even if there are still performance issues. > But zero-copy is a Linux generic feature that can be used by other VMMs as well if the BE service drivers want to incorporate. If we can make mp device VMM-agnostic (it may be not yet in current patch), that will help Linux more. Thx, Eddie-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/