[openstack-dev] [nova] Running large instances with CPU pinning and OOM

Blair Bethwaite blair.bethwaite at gmail.com
Wed Sep 27 22:55:01 UTC 2017

Hi Prema

On 28 September 2017 at 07:10, Premysl Kouril <premysl.kouril at gmail.com> wrote:
> Hi, I work with Jakub (the op of this thread) and here is my two
> cents: I think what is critical to realize is that KVM virtual
> machines can have substantial memory overhead of up to 25% of memory,
> allocated to KVM virtual machine itself. This overhead memory is not

I'm curious what sort of VM configuration causes such high overheads,
is this when using highly tuned virt devices with very large buffers?

> This KVM virtual machine overhead is what is causing the OOMs in our
> infrastructure and that's what we need to fix.

If you are pinning multiple guests per NUMA node in a multi-NUMA node
system then you might also have issues with uneven distribution of
system overheads across nodes, depending on how close to the sun you
are flying.


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