From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Limpach Subject: Re: [RFC PATCH 34/35] Add the Xen virtual network device driver. Date: Tue, 9 May 2006 15:00:27 +0100 Message-ID: <20060509140027.GD7834@cl.cam.ac.uk> References: <20060509131632.GB7834@cl.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: xen-devel@lists.xensource.com, virtualization@lists.osdl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, chrisw@sous-sol.org, ian.pratt@xensource.com Return-path: To: Herbert Xu Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com List-Id: netdev.vger.kernel.org On Tue, May 09, 2006 at 11:26:03PM +1000, Herbert Xu wrote: > Christian Limpach wrote: > > > > Possibly having to page in the process and switching to it would add > > to the live migration time. More importantly, having to install an > > additional program in the guest is certainly not very convenient. > > Sorry I'm still not convinced. What's there to stop me from suspending > my laptop to disk, moving it from port A to port B and resuming it? > > Wouldn't I be in exactly the same situation? By the same reasoning we'd > be adding a gratuitous ARP routine to every single laptop network driver. It is the same situation except that in the laptop case you don't care that reconfiguring your network will take a second or a few. For live migration we're looking at network downtime from as low as 60ms to something like 210ms on a busy virtual machine. I'm not saying that a userspace solution wouldn't work but it would probably add a measurable delay to the network downtime during live migration. You might also find the following paper an interesting read: http://www.cl.cam.ac.uk/Research/SRG/netos/papers/2005-migration-nsdi-pre.pdf christian