From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59976) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TVAaS-0007Yk-4k for qemu-devel@nongnu.org; Sun, 04 Nov 2012 19:30:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TVAaQ-00072V-EZ for qemu-devel@nongnu.org; Sun, 04 Nov 2012 19:30:44 -0500 Received: from ozlabs.org ([2402:b800:7003:1:1::1]:55758) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TVAaP-00070e-UV for qemu-devel@nongnu.org; Sun, 04 Nov 2012 19:30:42 -0500 Date: Mon, 5 Nov 2012 11:31:58 +1100 From: David Gibson Message-ID: <20121105003158.GX27695@truffula.fritz.box> References: <20121102031011.GM27695@truffula.fritz.box> <87sj8sgnku.fsf@elfo.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87sj8sgnku.fsf@elfo.mitica> Subject: Re: [Qemu-devel] Testing migration under stress List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: aik@ozlabs.ru, qemu-devel@nongnu.org On Fri, Nov 02, 2012 at 02:07:45PM +0100, Juan Quintela wrote: > David Gibson wrote: > > Asking for some advice on the list. > > > > I have prorotype savevm and migration support ready for the pseries > > machine. They seem to work under simple circumstances (idle guest). > > To test them more extensively I've been attempting to perform live > > migrations (just over tcp->localhost) which the guest is active with > > something. In particular I've tried while using octave to do matrix > > multiply (so exercising the FP unit) and my colleague Alexey has tried > > during some video encoding. > > > > However, in each of these cases, we've found that the migration only > > completes and the source instance only stops after the intensive > > workload has (just) completed. What I surmise is happening is that > > the workload is touching memory pages fast enough that the ram > > migration code is never getting below the threshold to complete the > > migration until the guest is idle again. > > > > Does anyone have some ideas for testing this better: workloads that > > are less likely to trigger this behaviour, or settings to tweak in the > > migration itself to make it more likely to complete migration while > > the workload is still active. > > You can: > > migrate_set_downtime 2s (or so) > > I normally run stress, and you move the memory that it dirties until it > converges (depends a lot of your networking). So, I'm using tcp to localhost, so it should be really fast, but it doesn't seem to be :/. I suspect there are some other bugs here. > Doing anything that is really memory intensive is basically never gonig > to converge. Well, I didn't think the loads I chose would be memory limited (especially the video encode), but.. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson