On Fri, May 03, 2013 at 12:47:43AM -0400, [email protected] wrote: > From: KOSAKI Motohiro <[email protected]> > > Currently glibc rt/tst-cpuclock2 test(*) sporadically fails because > scheduler delta can be accounted twice from thread_group_cputimer() > and account_group_exec_runtime(). > > Finally, clock_nanosleep() wakes up before an argument. This is posix > violation. This issue was introduced by commit d670ec1317 (posix-cpu-timers: > Cure SMP wobbles). > > (*) > http://sourceware.org/git/?p=glibc.git;a=blob;f=rt/tst-cpuclock2.c;h=6752721717f959e89c0d692b3f1ee082d507eec2;hb=HEAD > > Cc: Olivier Langlois <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Frederic Weisbecker <[email protected]> > Cc: Ingo Molnar <[email protected]> > Signed-off-by: Peter Zijlstra <[email protected]> > Signed-off-by: KOSAKI Motohiro <[email protected]> [...] > diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c > index 8fd709c..e56be4c 100644 > --- a/kernel/posix-cpu-timers.c > +++ b/kernel/posix-cpu-timers.c > @@ -220,7 +220,7 @@ static int cpu_clock_sample(const clockid_t which_clock, > struct task_struct *p, > cpu->cpu = virt_ticks(p); > break; > case CPUCLOCK_SCHED: > - cpu->sched = task_sched_runtime(p); > + cpu->sched = task_sched_runtime(p, true); > break; > } > return 0; > @@ -250,8 +250,13 @@ void thread_group_cputimer(struct task_struct *tsk, > struct task_cputime *times) > * values through the TIMER_ABSTIME flag, therefore we have > * to synchronize the timer to the clock every time we start > * it. > + * > + * Do not add the current delta, because > + * account_group_exec_runtime() will also this delta and we > + * wouldn't want to double account time and get ahead of > + * ourselves. > */ > - thread_group_cputime(tsk, &sum); > + thread_group_cputime(tsk, false, &sum); > raw_spin_lock_irqsave(&cputimer->lock, flags);
I wonder if we should move thread_group_cputime() inside this lock. Otherwise we can miss some updates in-between. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
