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

Mike Galbraith
2010-12-03T15:09:47Z

On Fri, 2010-12-03 at 09:48 -0500, Rik van Riel wrote:
> On 12/03/2010 09:45 AM, Mike Galbraith wrote:
>
> > I'll have to go back and re-read that. Off the top of my head, I see no
> > way it could matter which container the numbers live in as long as they
> > keep advancing, and stay in the same runqueue. (hm, task weights would
> > have to be the same too or scaled. dangerous business, tinkering with
> > vruntimes)
>
> They're not necessarily in the same runqueue, the
> VCPU that is given time might be on another CPU
> than the one that was spinning on a lock.

I don't think pumping vruntime cross cfs_rq would be safe, for the
reason noted (et al). No competition means vruntime is meaningless.
Donating just advances a clock that nobody's looking at.

-Mike