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On Thu, 28 Sep 2017, Premysl Kouril wrote:

>> Only the memory mapped for the guest is striclty allocated from the
>> NUMA node selected. The QEMU overhead should float on the host NUMA
>> nodes. So it seems that the "reserved_host_memory_mb" is enough.
>>
>
> Even if that would be true and overhead memory could float in NUMA
> nodes it generally doesn't prevent us from running into OOM troubles.
> No matter where (in which NUMA node) the overhead memory gets
> allocated, it is not included in available memory calculation for that
> NUMA node when provisioning new instance and thus can cause OOM (once
> the guest operating system  of the newly provisioned instance actually
> starts allocating memory which can only be allocated from its assigned
> NUMA node).

Some of the discussion on this bug may be relevant:

https://bugs.launchpad.net/nova/+bug/1683858

-- 
Chris Dent                      (⊙＿⊙')         https://anticdent.org/
freenode: cdent                                         tw: @anticdent