[libvirt] [PATCH v5 2/2] conf: List only online cpus for virsh emulatorpin

Peter Krempa pkrempa at redhat.com
Tue Dec 6 12:10:37 UTC 2016

On Tue, Dec 06, 2016 at 13:01:48 +0100, Viktor Mihajlovski wrote:
> On 06.12.2016 12:33, Peter Krempa wrote:
> > On Fri, Nov 25, 2016 at 14:53:07 +0530, Nitesh Konkar wrote:


> > Additionally we historically treat the "all bits set" cpu map as
> > that there is no pinning configured. This would change this
> > behavior. When the VM is started, the real cpu map should be
> > returned, but for the config time I think the current state is
> > correct and doing your change would be incorrect.
> I have no strong opinion on whether the CPU mask should match the host
> online mask for the defined case, but the "all bits set" map will
> change with the old code as well, if new CPUs are added via hotplug.

CPU hotplug on the host is very uncommon and thus not tested very well.

> The crux is that we don't have any way to find out there's in fact no
> pinning in place for a process nor a way to "unpin" it.

That is true indeed. It's not possible via the API. It's fully possible
via XML though.

For unpinning I have an unfinished series adding a flag to remove
pinning since since any other method is not reliable enough.

Finally I think that the "all ones" bitmap should cover the full map the
user sends to libvirt. This would differentiate it from the "pinned to
current full set of cpus" case.
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