Re: [PATCH] cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available

[Marcelo Tosatti]

On Thu, Aug 29, 2019 at 08:16:41PM +0800, Wanpeng Li wrote:
> > Current situation regarding haltpoll driver is:
> >
> > overcommit group: haltpoll driver is not loaded by default, they are
> > happy.
> >
> > non overcommit group: boots without "realtime hints" flag, loads haltpoll driver,
> > happy.
> >
> > Situation with patch above:
> >
> > overcommit group: haltpoll driver is not loaded by default, they are
> > happy.
> >
> > non overcommit group: boots without "realtime hints" flag, haltpoll driver
> > cannot be loaded.
> 
> non overcommit group, if they don't care latency/performance, they
> don't need to enable haltpoll, "realtime hints" etc. Otherwise, they
> should better tune.

As mentioned before, "being overcommitted" is a property which is transitional.

A static true/false scheme reflects this poorly.

Therefore the OS should detect it and act accordingly.