From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Miller <davem@davemloft.net>, linux-kernel@vger.kernel.org
Subject: Re: process time < thread time?
Date: Thu, 1 Sep 2011 12:39:05 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1109011226160.2723@ionos> (raw)
In-Reply-To: <1314871884.7945.20.camel@twins>
On Thu, 1 Sep 2011, Peter Zijlstra wrote:
> On Thu, 2011-09-01 at 11:56 +0200, Thomas Gleixner wrote:
> > The untested patch below should cure this.
> >
>
> > diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
> > index 58f405b..42378cb 100644
> > --- a/kernel/posix-cpu-timers.c
> > +++ b/kernel/posix-cpu-timers.c
> > @@ -250,7 +250,7 @@ void thread_group_cputime(struct task_struct *tsk,
> > struct task_cputime *times)
> > do {
> > times->utime = cputime_add(times->utime, t->utime);
> > times->stime = cputime_add(times->stime, t->stime);
> > - times->sum_exec_runtime += t->se.sum_exec_runtime;
> > + times->sum_exec_runtime += task_sched_runtime(t);
> > } while_each_thread(tsk, t);
> > out:
> > rcu_read_unlock();
>
> I think we just deadlocked:
That's why I said untested :)
> cpu_clock_sample_group()
> CPUCLOCK_SCHED: thread_group_sched_runtime()
> task_rq_lock() <-.
> thread_group_cputime() |
> task_sched_runtime() |
> task_rq_lock() ------'
>
>
> Also, having to take locks here is sad, but yeah if we want to cure this
> there's not much we can do about that.
Yeah :(
next prev parent reply other threads:[~2011-09-01 10:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-01 3:07 process time < thread time? David Miller
2011-09-01 9:56 ` Thomas Gleixner
2011-09-01 10:11 ` Peter Zijlstra
2011-09-01 10:39 ` Thomas Gleixner [this message]
2011-09-01 10:54 ` Peter Zijlstra
2011-09-01 14:54 ` Thomas Gleixner
2011-09-01 14:56 ` David Miller
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