Re: [Xen-devel] [PATCH 2/2] xen: merge temporary vcpu pinning scenarios

[Juergen Gross <jgross@xxxxxxxx>]

On 23.07.19 15:07, Dario Faggioli wrote:
> On Tue, 2019-07-23 at 11:20 +0200, Juergen Gross wrote:
> > Today there are three scenarios which are pinning vcpus temporarily
> > to
> > a single physical cpu:
> >
> > - NMI/MCE injection into PV domains
> > - wait_event() handling
> > - vcpu_pin_override() handling
> >
> > Each of those cases are handled independently today using their own
> > temporary cpumask to save the old affinity settings.
> >
> > The three cases can be combined as the two latter cases will only pin
> > a vcpu to the physical cpu it is already running on, while
> > vcpu_pin_override() is allowed to fail.
> >
> > So merge the three temporary pinning scenarios by only using one
> > cpumask and a per-vcpu bitmask for specifying which of the three
> > scenarios is currently active (they are allowed to nest).
> Right. And, after this patch, all the three cases above and
> suspend/resume, all use cpu_hard_affinity_saved.
>
> Can you add a paragraph, either here in the changelog, on in a comment
> (e.g., at the top or inside of vcpu_set_tmp_affinity()), about why this
> is all fine?
Yes.


Juergen


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