Re: [Engine-devel] CPU Pinning @engine
On 05/17/2012 04:24 PM, Gary Kotton wrote:
On 05/17/2012 02:42 PM, Doron Fediuck wrote:
> Hi All,
> Currently the VDSM has a CPU pinning hook.
> We'd like to add better support of it into the engine itself.
> Here's a design draft to cover it:
> http://www.ovirt.org/wiki/Features/Design/cpu-pinning
>
> Please review and comment if needed.
Hi,
I have a number of comments:
1. Will the user have any indication for the maximum amount of vCPU's?
2. What happens if a VM is already configured with the same CPU pin
info? Will this be shared?
3. Would it possible to extend this to limit the MHz of CPU that can be
allocated to a VM?
5. If the VM has more than one core, will each core have to be mapped?
6. "similar to the existing hook Shahar wrote" - can you please put a
link the the hook that Shahar wrote. :) This will be helpful for those
of us unfamiliar with it.
7. Why will live migration not be supported? What is the gap to have
this type of support?
+1 on the above.
In addition, it should be nice to reveal the host cpu topology so the
user will be able to match the virtual one.
Getting the hyperthread topology is important factor as well.
Numa is not mentioned at all. It should be highly desirable to expose
the numa topology and add numa pinning using numactl.
Since you're refactoring this code, adding options for the new numda
daemon would be important too.
Another important factor is the ability to pin not only the vcpu threads
but also to pin 'service threads' in the host, potential to other
physical cpus. Examples for such are the qemu io thread, vhost threads, etc.
Regards,
Dor
Thanks
Gary
> Thanks!
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