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Date: Tue, 11 Feb 2014 19:30:54 +0100
From: Stefan Priebe <s.priebe@profihost.ag>
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Subject: Re: [Qemu-devel] memory allocation of migration changed?
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Orit Wasserman <owasserm@redhat.com>, Peter Lieven <pl@kamp.de>, qemu-devel <qemu-devel@nongnu.org>, Dave Gilbert <dgilbert@redhat.com>, Juan Quintela <quintela@redhat.com>

Am 11.02.2014 16:44, schrieb Stefan Hajnoczi:
> On Tue, Feb 11, 2014 at 3:54 PM, Stefan Priebe - Profihost AG
> <s.priebe@profihost.ag> wrote:
>> in the past (Qemu 1.5) a migration failed if there was not enogh memory
>> on the target host available directly at the beginning.
>>
>> Now with Qemu 1.7 i've seen succeeded migrations but the kernel OOM
>> memory killer killing qemu processes. So the migration seems to takes
>> place without having anough memory on the target machine?
>
> How much memory is the guest configured with?  How much memory does
> the host have?

Guest: 48GB
Host: 192GB

> I wonder if there are zero pages that can be migrated almost "for
> free" and the destination host doesn't touch.  When they are touched
> for the first time after migration handover, they need to be allocated
> on the destination host.  This can lead to OOM if you overcommitted
> memory.

In the past the migration failed immediatly with exit code 255.

> Can you reproduce the OOM reliably?  It should be possible to debug it
> and figure out whether it's just bad luck or a true regression.

So there is no known patch changing this behaviour?

What is about those?
fc1c4a5d32e15a4c40c47945da85ef9c1e0c1b54
211ea74022f51164a7729030b28eec90b6c99a08
f1c72795af573b24a7da5eb52375c9aba8a37972

Stefan