From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: kvm-27 vs 28 I/O speed Date: Thu, 12 Jul 2007 08:37:10 +0300 Message-ID: <4695BE06.6060609@qumranet.com> References: <1183748857.10287.198.camel@localhost> <46909CFD.9050806@qumranet.com> <1184013180.10287.278.camel@localhost> <46931CC9.8060106@qumranet.com> <1184180092.26210.49.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: Dave Hansen Return-path: In-Reply-To: <1184180092.26210.49.camel@localhost> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Dave Hansen wrote: > On Tue, 2007-07-10 at 08:44 +0300, Avi Kivity wrote: > >> What does 'top' on the host show in both cases? >> > > On the fast one (kvm-27) I just see the dd as a flash in top. It > doesn't stay for long. The VM isn't very responsive during the dd. > > On the slow (kvm-28) one, I see the dd in top creeping along, using ~2% > of the CPU. The guest is responsive during this time > > >> There was a change in kvm userspace that affected IDE. Can you try >> kvm-27 userspace with a kvm-28 kernel module? >> > > That's actually what I've been doing the whole time. Sorry, my initial > problem description must not have been very clear. I've been using the > kvm-28 modules the entire time, and only varying the userspace. > > The IDE changes do look suspect. > > Can you confirm it by backing out that one patch? I don't see how it can cause this slowdown, except by causing a different driver to be loaded or perhaps with different settings. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/