Re: [RFC PATCH 14/15] nohz_task: Clear nohz task attribute onexit()

From: Frederic Weisbecker
Date: Tue Dec 21 2010 - 09:22:35 EST


On Tue, Dec 21, 2010 at 09:07:45AM +0100, Peter Zijlstra wrote:
> On Tue, 2010-12-21 at 02:48 +0100, Frederic Weisbecker wrote:
> > On Mon, Dec 20, 2010 at 05:30:28PM +0100, Peter Zijlstra wrote:
> > > On Mon, 2010-12-20 at 16:24 +0100, Frederic Weisbecker wrote:
> > > >
> > > > Clear the nohz task attribute when a task exits, clear the cpu
> > > > mask and restart the tick if necessary.
> > > >
> > > I'm not quite sure this all makes sense, I mean, we're going from 1 to 0
> > > tasks, right?
> >
> > Not necessarily, other tasks can be on the runqueue while that nohz task
> > exits, or we can be alone in which case the tick might be stopped and
> > we need to restart it because rq->nr_running > 1 won't make much sense
> > anymore without the nohz task and if a new task gets enqueued, the tick
> > won't restart until a second one gets in.
>
> Urgh, so that mask is set even if you're not currently in that mode?
> That's 'interesting'..

I don't get what you mean.
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