[openstack-hpc] CPU intensive apps on OpenStack

Blair Bethwaite blair.bethwaite at gmail.com
Fri Apr 17 05:36:02 UTC 2015


Hi Tim,

What's your reference on disabling EPT? I can find some fairly old
stuff on this, but I thought newer processors had improved performance
here to lower page fault overheads... so I guess I'm wondering if
you've seen a recent evaluation somewhere?

Re. NUMA etc, it seems like the most important thing if you're running
large memory apps inside your guests is to make sure the guest is
pinned (both CPU and NUMA wise) and sees a NUMA topology that matches
how it is pinned on the host. I haven't had a chance to try it yet but
I thought this was all now possible Juno. Beyond that you probably
want the guest kernel to be NUMA sassy as well, so it needs (IIRC)
Linux 3.13+ to get the numa_balancing (nee autonuma) goodies. I'm not
sure if for such cases you might actually want to disable numa
balancing on the host or whether the pinning would effectively remove
any overhead there anyway...

PS: +1 on the meetup suggestion

-- 
Cheers,
~Blairo



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