Re: [Qemu-devel] memory allocation of migration changed?

[Stefan Hajnoczi]

On Tue, Feb 11, 2014 at 3:54 PM, Stefan Priebe - Profihost AG
<address@hidden> 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