Re: [PATCH] scheduler hints

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > Seems to me this particular case is covered by increasing
> > priority when grabbing the semaphore and normalizing
> > priority when releasing.  
> > 
> > Only root can do that - but only root does real-time
> > anyway. And I guess only rood should be able to increase 
> > its timeslice too...
> 
> Increasing its priority has no bearing on whether it runs out of
> timeslice, however.  The idea here is to help the task complete its
> critical section (and thus not block other tasks) before being
> preempted.  Only way to achieve that is boost its timeslice.
> 
> Boosting its priority will assure there is no priority inversion and
> that, eventually, the task will run - but it does nothing to avoid the
> nasty "grab resource, be preempted, reschedule a bunch, finally find
> yourself running again since everyone else blocked" issue.
> 
> And I don't think only root should be able to do this.  If we later
> punish the task (take back the timeslice we gave it) then this is
> fair.

Another possibility might be to allow it to *steal* time from another
processes... Of course only processes of same UID ;-).
									Pavel
-- 
(about SSSCA) "I don't say this lightly.  However, I really think that the U.S.
no longer is classifiable as a democracy, but rather as a plutocracy." --hpa