Re: Are ALL_TASKS_PI on in 2.6.16-rt7?

From: Ingo Molnar
Date: Sun Mar 26 2006 - 16:35:31 EST



* Esben Nielsen <simlo@xxxxxxxxxx> wrote:

> On Sun, 26 Mar 2006, Ingo Molnar wrote:
>
> >
> > * Esben Nielsen <simlo@xxxxxxxxxx> wrote:
> >
> > > It just looks like also normal, non-rt tasks are boosting.
> >
> > correct. We'd like to make sure the PI code is correct - and for
> > PI-futex it makes sense anyway.
> >
>
> It wont work 100% when a task is boosted to a normal, non-rt prio well
> since at scheduler_tick()
> p->prio = effective_prio(p);
> can be executed overwriting the boost.

yeah - but that's relatively rare, upon expiration of the timeslice.
The following would probably solve it: scheduler_tick() could take the
pi_lock (before taking the rq lock), update normal_prio, and then call
into rt_mutex_getprio() [just like setscheduler does] to set the
priority.

Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/