From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56440) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TUG6i-0006hm-0t for qemu-devel@nongnu.org; Fri, 02 Nov 2012 08:12:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TUG6d-0006Sg-7A for qemu-devel@nongnu.org; Fri, 02 Nov 2012 08:12:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10376) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TUG6c-0006SZ-V9 for qemu-devel@nongnu.org; Fri, 02 Nov 2012 08:12:11 -0400 Message-ID: <5093B8A9.4060501@redhat.com> Date: Fri, 02 Nov 2012 14:12:25 +0200 From: Orit Wasserman MIME-Version: 1.0 References: <20121102031011.GM27695@truffula.fritz.box> In-Reply-To: <20121102031011.GM27695@truffula.fritz.box> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Testing migration under stress List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aik@ozlabs.ru, qemu-devel@nongnu.org, quintela@redhat.com On 11/02/2012 05:10 AM, 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. > As you are doing local migration one option is to setting the speed higher than line speed , as we don't actually send the data, another is to set high downtime. > 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. > The workload you chose is really bad for live migration, as all the guest does is dirtying his memory. I recommend looking for workload that does some networking or disk IO. Vinod succeeded running SwingBench and SLOB benchmarks that converged ok, I don't know if they run on pseries, but similar workload should be ok(small database/warehouse). We found out that SpecJbb on the other hand is hard to converge. Web workload or video streaming also do the trick. Cheers, Orit > 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. >