From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Shah Subject: Re: [PATCH v4 00/12] virtio: s4 support Date: Thu, 8 Dec 2011 17:26:40 +0530 Message-ID: <20111208115640.GE23531@amit-x200.redhat.com> References: <87wra8j13m.fsf@rustcorp.com.au> <20111207074456.GD4651@amit-x200.redhat.com> <87liqoirgm.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <87liqoirgm.fsf@rustcorp.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Rusty Russell Cc: linux-kernel@vger.kernel.org, "Michael S. Tsirkin" , levinsasha928@gmail.com, Virtualization List List-Id: virtualization@lists.linuxfoundation.org On (Wed) 07 Dec 2011 [21:22:41], Rusty Russell wrote: > On Wed, 7 Dec 2011 13:14:56 +0530, Amit Shah wrote: > > On (Wed) 07 Dec 2011 [17:54:29], Rusty Russell wrote: > > > I figure there's a reason, but it seems a bit weird :) > > > > Well, there is one reason right now: migrating storage along with > > VMs. The guest needs to sync all data to the disk before the target > > host accesses the image file. > > I don't see why. Sure, if qemu (or whatever) is doing buffering, it > needs to flush that. It doesn't, last I looked, it just maps to > read/write. > > What am I missing? I'm sorry, I got confused. The external file migration Gleb mentioned, though, is something that libvirt uses right now and causes guest time craziness so S4 is one (and natural) way to solve it. Amit