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Date: Tue, 10 Nov 2009 19:24:15 +0100 From: Stanislaw Gruszka <sgruszka@...hat.com> To: Oleg Nesterov <oleg@...hat.com> Cc: Peter Zijlstra <peterz@...radead.org>, Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>, Spencer Candland <spencer@...ehost.com>, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu> Subject: Re: utime/stime decreasing on thread exit On Tue, Nov 10, 2009 at 06:40:08PM +0100, Oleg Nesterov wrote: > > One other exception is: > > fastpath_timer_check() -> thread_group_cputimer() -> thread_group_cputime() > > > > We can solve this like that: > > > > --- a/kernel/posix-cpu-timers.c > > +++ b/kernel/posix-cpu-timers.c > > @@ -1375,13 +1375,8 @@ static inline int fastpath_timer_check(struct task_struct *tsk) > > } > > > > sig = tsk->signal; > > - if (!task_cputime_zero(&sig->cputime_expires)) { > > - struct task_cputime group_sample; > > - > > - thread_group_cputimer(tsk, &group_sample); > > - if (task_cputime_expired(&group_sample, &sig->cputime_expires)) > > - return 1; > > - } > > + if (!task_cputime_zero(&sig->cputime_expires)) > > + return 1; > > > > return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY; > > } > > > > Or stay with task_cputime_expired() but only if cputimer is currently running. > > Oh. I forgot this code completely, can't comment. > > Can't we ensure that fastpath_timer_check() never do while_each_thread() ? Removing possibility to call while_each_tread() from fastpath_timer_check() was exactly my intension here, perhaps I was not clear. > IOW, if sig->cputime_expires != 0 then ->running must be true. > At least, shouldn't stop_process_timers() clear sig->cputime_expires ? I'm going to think about that. However as far seems, checking ->running explicitly and goto slow patch when is not true is safer solution. Stanislaw -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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