From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC][PATCH v2 0/3] Provide a zero-copy method on KVM virtio-net. Date: Sat, 03 Apr 2010 19:32:33 +0300 Message-ID: <4BB76DA1.4050904@redhat.com> References: <1270193100-6769-1-git-send-email-xiaohui.xin@intel.com> <1270252268.13897.14.camel@w-sridhar.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: xiaohui.xin@intel.com, 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, davem@davemloft.net To: Sridhar Samudrala Return-path: Received: from mx1.redhat.com ([209.132.183.28]:18050 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359Ab0DCQcs (ORCPT ); Sat, 3 Apr 2010 12:32:48 -0400 In-Reply-To: <1270252268.13897.14.camel@w-sridhar.beaverton.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: On 04/03/2010 02:51 AM, Sridhar Samudrala wrote: > On Fri, 2010-04-02 at 15:25 +0800, xiaohui.xin@intel.com 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. >> > What is the advantage of this approach compared to PCI-passthrough > of the host NIC to the guest? > swapping/ksm/etc independence from host hardware live migration > Does this require pinning of the entire guest memory? Or only the > send/receive buffers? > If done correctly, just the send/receive buffers. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.