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Date: Tue, 11 Feb 2014 19:32:46 +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: Peter Lieven <pl@kamp.de>, Stefan Hajnoczi <stefanha@gmail.com>
Cc: Orit Wasserman <owasserm@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Dave Gilbert <dgilbert@redhat.com>, Juan Quintela <quintela@redhat.com>

Am 11.02.2014 17:22, schrieb Peter Lieven:
>
>
>> Am 11.02.2014 um 16:44 schrieb Stefan Hajnoczi <stefanha@gmail.com>:
>>
>> 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?
>>
>> 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.
>>
>> 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.
>>
>> Stefan
>
> Kernel Version would also be interesting as well as thp and ksm settings.

Kernel Host: 3.10.26

What's thp / ksm? how to get those settings?

Greets,
Stefan