[pve-devel] qemu-server:add support for hugetlbfs

[Dietmar Maurer]

> On December 21, 2014 at 1:23 PM Alexandre DERUMIER <aderumier at odiso.com>
> wrote:
> 
> 
> >>1.) Is there some edivence that it is faster (under realistic workload)?
> 
> I known that transparent hugepage can be really a problem with a lot of
> database (oracle,mysql,redis,..)
> I never bench it myself, but I hope that Cesar will do it ;).
> 
> Disable transparent hugepage is a solution, but it's disable it for all the
> vms.
> 
> I think that static hugepage can do the job, but it need to be tested.

Yes, before introducing such feature we want to see if there is any advantage.

> >>2.) Where do we free/dealloc those hugepages? Are the associated with the
> >>KVM 
> >>process somehow? 
> 
> I'm not sure that when hupage are defined, they use memory by default.
> 
> But when the kvm process is starting, the memory is allocated/reserverd for
> the kvm process, 

but there is a race condition in your implementation, so it is not sure which
kvm process gets
the hugepages (if several VM start at once)?

> and the memory is free up on kvm process stop.

But hugpages keep reserved? I have no idea if that is a problem?