From: Muli Ben-Yehuda Subject: Re: [PATCH 0/16 v6] PCI: Linux kernel SR-IOV support Date: Sun, 9 Nov 2008 08:41:48 +0200 Message-ID: <20081109064147.GD7123@il.ibm.com> References: <20081106154351.GA30459@kroah.com> <894107.30288.qm@web45108.mail.sp1.yahoo.com> <20081106164919.GA4099@kroah.com> <20081106174741.GC11773@parisc-linux.org> <20081106175308.GA17027@kroah.com> <49137255.9010104@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Greg KH , Matthew Wilcox , H L , Yu Zhao , randy.dunlap@oracle.com, grundler@parisc-linux.org, achiang@hp.com, linux-pci@vger.kernel.org, rdreier@cisco.com, linux-kernel@vger.kernel.org, jbarnes@virtuousgeek.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, mingo@elte.hu, Chris Wright To: Anthony Liguori Return-path: Content-Disposition: inline In-Reply-To: <49137255.9010104@codemonkey.ws> Sender: linux-pci-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Nov 06, 2008 at 04:40:21PM -0600, Anthony Liguori wrote: > We've been talking about avoiding hardware passthrough entirely and > just backing a virtio-net backend driver by a dedicated VF in the > host. That avoids a huge amount of guest-facing complexity, let's > migration Just Work, and should give the same level of performance. I don't believe that it will, and every benchmark I've seen or have done so far shows a significant performance gap between virtio and direct assignment, even on 1G ethernet. I am willing however to reserve judgement until someone implements your suggestion and actually measures it, preferably on 10G ethernet. No doubt device assignment---and SR-IOV in particular---are complex, but I hardly think ignoring it as you seem to propose is the right approach. Cheers, Muli -- The First Workshop on I/O Virtualization (WIOV '08) Dec 2008, San Diego, CA, http://www.usenix.org/wiov08/ <-> SYSTOR 2009---The Israeli Experimental Systems Conference http://www.haifa.il.ibm.com/conferences/systor2009/