[Engine-devel] CPU Overcommit Feature

[Dan Kenigsberg]

On Mon, Dec 17, 2012 at 09:37:57AM -0500, Greg Padgett wrote:
> Hi,
> 
> I've been working on a feature to allow CPU Overcommitment of hosts
> in a cluster.  This first stage allows the engine to consider host
> cpu threads as cores for the purposes of VM resource allocation.
> 
> This wiki page has further details, your comments are welcome!
> http://www.ovirt.org/Features/cpu_overcommit

I've commented about the vdsm/engine API on
http://gerrit.ovirt.org/#/c/10144/ but it is probably better to
reiterate it here.

The suggested API is tightly coupled with an ugly hack we pushed to vdsm
in order not to solve the issue properly on the first strike.

If we had not have report_host_threads_as_cores, I think we'd have a
simpler API reporting only cpuThreads and cpuCores; with no funny
boolean flags.

Let us strive to that position as much as we can.

How about asking whoever used report_host_threads_as_cores to unset it
once they install Engine 3.2 ? I think that these are very few people,
that would not mind this very much.

If this is impossible, I'd add a cpuCores2, always reporting the true
number, to be used by new Engines. We may even report it only on the
very few cases of report_host_threads_as_cores being set.

Dan.