Re: [RFC -v3 PATCH 2/3] sched: add yield_to function

Hillf Danton
2011-01-04T17:12:45Z

On Wed, Jan 5, 2011 at 1:08 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> On Wed, 2011-01-05 at 00:51 +0800, Hillf Danton wrote:
>> Where is the yield_to callback in the patch for RT schedule class?
>> If @p is RT, what could you do?
>
> RT guests are a pipe dream, you first need to get the hypervisor (kvm in
> this case) to be RT, which it isn't. Then you either need to very
> statically set-up the host and the guest scheduling constraints (not
> possible with RR/FIFO) or have a complete paravirt RT scheduler which
> communicates its requirements to the host.
>
Even guest is not RT, you could not prevent it from being preempted by
RT task which has nothing to do guests.