Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752301Ab0BKHlp (ORCPT ); Thu, 11 Feb 2010 02:41:45 -0500 Received: from mga09.intel.com ([134.134.136.24]:33188 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751890Ab0BKHln convert rfc822-to-8bit (ORCPT ); Thu, 11 Feb 2010 02:41:43 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.49,450,1262592000"; d="scan'208";a="491568637" From: "Xin, Xiaohui" To: Arnd Bergmann CC: "netdev@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "mingo@elte.hu" , "mst@redhat.com" , "jdike@c2.user-mode-linux.org" Date: Thu, 11 Feb 2010 15:40:08 +0800 Subject: RE: [PATCH 0/3] Provide a zero-copy method on KVM virtio-net. Thread-Topic: [PATCH 0/3] Provide a zero-copy method on KVM virtio-net. Thread-Index: AcqqVqLdI8DojazvQRiFmBFfis0PWQAlPoEw Message-ID: <97F6D3BD476C464182C1B7BABF0B0AF5C11F641A@shzsmsx502.ccr.corp.intel.com> References: <1265802540-6122-1-git-send-email-xiaohui.xin@intel.com> <201002101440.05063.arnd@arndb.de> In-Reply-To: <201002101440.05063.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: 2110 Lines: 50 >>On Wednesday 10 February 2010, Xin Xiaohui wrote: > >The idea is simple, just to pin the guest VM user space and then > >let host NIC driver has the chance to directly DMA to it. > >The patches are based on vhost-net backend driver. We add a device > >which provides proto_ops as sendmsg/recvmsg to vhost-net to > >send/recv directly to/from the NIC driver. KVM guest who use the > >vhost-net backend may bind any ethX interface in the host side to > >get copyless data transfer thru guest virtio-net frontend. >> >> We provide multiple submits and asynchronous notifiicaton to > >vhost-net too. >This does a lot of things that I had planned for macvtap. It's >great to hear that you have made this much progress. > >However, I'd hope that we could combine this with the macvtap driver, >which would give us zero-copy transfer capability both with and >without vhost, as well as (tx at least) when using multiple guests >on a macvlan setup. You mean the zero-copy can work with macvtap driver without vhost. May you give me some detailed info about your macvtap driver and the relationship between vhost and macvtap to make me have a clear picture then? >For transmit, it should be fairly straightforward to hook up >your zero-copy method and the vhost-net interface into the >macvtap driver. > >You have simplified the receiv path significantly by assuming >that the entire netdev can receive into a single guest, right? Yes. >I'm assuming that the idea is to allow VMDq adapters to simply >show up as separate adapters and have the driver handle this >in a hardware specific way. Does the VMDq driver do so now? >My plan for this was to instead move support for VMDq into the >macvlan driver so we can transparently use VMDq on hardware where >available, including zero-copy receives, but fall back to software >operation on non-VMDq hardware. Arnd -- 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/