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Re: [PATCH 04/10] nohz: Remove useless argument on tick_nohz_task_switch()

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH 04/10] nohz: Remove useless argument on tick_nohz_task_switch()
Date 2015-08-03 15:10 +0200
Message-ID <pTnF8-3WH-13@gated-at.bofh.it> (permalink)
References <pPrQZ-3Wb-3@gated-at.bofh.it> <pPrR1-3Wb-19@gated-at.bofh.it> <pTnlL-3kJ-21@gated-at.bofh.it> <pTnvr-3w4-9@gated-at.bofh.it>
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On Mon, Aug 03, 2015 at 02:49:54PM +0200, Frederic Weisbecker wrote:
> On Mon, Aug 03, 2015 at 02:39:59PM +0200, Peter Zijlstra wrote:
> > On Thu, Jul 23, 2015 at 06:42:09PM +0200, Frederic Weisbecker wrote:
> > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > > index 78b4bad10..4d34035 100644
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -2489,7 +2489,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
> > >  		put_task_struct(prev);
> > >  	}
> > >  
> > > -	tick_nohz_task_switch(current);
> > > +	tick_nohz_task_switch();
> > >  	return rq;
> > >  }
> > 
> > OK, so I just noticed this one. Please explain? WTF does it make sense
> > to have per task tick state?
> > 
> > If we have >1 tasks, we need the tick. If we have 1 task, per-task ==
> > per-cpu.
> > 
> > So what gives?
> 
> tick_nohz_task_switch() is removed in the end of the patchset. There is no
> more per task dependency after this specific set.

OK, I'll keep reading ;-)
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Re: [PATCH 04/10] nohz: Remove useless argument on  tick_nohz_task_switch() Peter Zijlstra <peterz@infradead.org> - 2015-08-03 14:50 +0200
  Re: [PATCH 04/10] nohz: Remove useless argument on  tick_nohz_task_switch() Frederic Weisbecker <fweisbec@gmail.com> - 2015-08-03 15:00 +0200
    Re: [PATCH 04/10] nohz: Remove useless argument on  tick_nohz_task_switch() Peter Zijlstra <peterz@infradead.org> - 2015-08-03 15:10 +0200

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