Re: [PATCH][retry 3] Add support for Pause Filtering to AMD SVM

Peter Zijlstra
2009-05-20T08:54:16Z

On Wed, 2009-05-20 at 11:49 +0300, Avi Kivity wrote:
> Peter Zijlstra wrote:
> >>> That said, I still thoroughly dislike this whole approach.
> >>>
> >>>
> >> Can you explain why? We have a thread that has detected that it's
> >> spinning. Keeping on spinning is a waste of cpu time. Why not let
> >> something else use the cpu?
> >>
> >
> > Because its a polling interface. I much prefer it if we were to get a
> > wakeup notification when the vcpu holding the lock releases it.
> >
>
> It's a fully virtualized guest. There's no way to get this without
> patching the guest kernel.

Yes there is.. virtualized monitor-wait stuff coupled with a
monitor-wait based spinlock implementation.

Once we go change silicon, you might as well do it right.