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Message-Id: <1229444288.7025.35.camel@twins>
Date: Tue, 16 Dec 2008 17:18:08 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc: Ingo Molnar <mingo@...e.hu>, Jason Baron <jbaron@...hat.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
Steven Rostedt <srostedt@...hat.com>
Subject: Re: sched: trace: update trace_sched_wakeup()
On Tue, 2008-12-16 at 10:47 -0500, Mathieu Desnoyers wrote:
> * Peter Zijlstra (peterz@...radead.org) wrote:
> > On Tue, 2008-12-16 at 08:07 +0100, Peter Zijlstra wrote:
> > > Add the information needed to distinguish 'real' wakeups from 'false'
> > > wakeups.
> >
> > I don't seem to be doing so well this morning...
> >
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> >
> > Thanks Dhaval!
> >
>
> Applied a modified version into the 2.6.27.9 LTTng tree. Thanks!
> (remembering that I should really move to 2.6.28-rc!)
Ingo pointed out that this generates build crap in ftrace which made me
look at the thing again, and I just realized we don't need it.
trace_sched_wakeup() gets called before we set p->state = TASK_RUNNING,
so by checking p->state in the callback we can see if its a real of
false wakeup.
The scheduler tracer in ftrace already exploits this.
> > > --- a/kernel/sched.c
> > > +++ b/kernel/sched.c
> > > @@ -2329,7 +2329,7 @@ out_activate:
> > > success = 1;
> > >
> > > out_running:
> > > - trace_sched_wakeup(rq, p);
> > > + trace_sched_wakeup(rq, p, success);
> > > check_preempt_curr(rq, p, sync);
> > >
> > > p->state = TASK_RUNNING;
--
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