(4/29/13 1:10 PM), Olivier Langlois wrote: > On Mon, 2013-04-29 at 01:06 -0400, KOSAKI Motohiro wrote: >> (4/27/13 12:40 AM), Olivier Langlois wrote: >>> >>> >>> Forbids the cputimer to drift ahead of its process clock by >>> blocking its update when a tick occurs while a autoreaping task >>> is currently in do_exit() between the call to release_task() and >>> its final call to schedule(). >>> >>> Any task stats update after having called release_task() will >>> be lost because they are added to the global process stats located >>> in the signal struct from release_task(). >>> >>> Ideally, you should postpone the release_task() call after the >>> final context switch to get all the stats added but this is >>> more complex to achieve. >>> >>> In other words, this is slowing down the cputimer so it keep the same >>> pace than the process clock but in fact, what should be done is to >>> speed up the process clock by adding the missing stats to it. >>> >>> Signed-off-by: Olivier Langlois <oliv...@trillion01.com> >>> --- >>> kernel/sched/fair.c | 10 +++++++++- >>> 1 file changed, 9 insertions(+), 1 deletion(-) >>> >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >>> index 7a33e59..52d7b10 100644 >>> --- a/kernel/sched/fair.c >>> +++ b/kernel/sched/fair.c >>> @@ -708,7 +708,15 @@ static void update_curr(struct cfs_rq *cfs_rq) >>> >>> trace_sched_stat_runtime(curtask, delta_exec, >>> curr->vruntime); >>> cpuacct_charge(curtask, delta_exec); >>> - account_group_exec_runtime(curtask, delta_exec); >>> + /* >>> + * Do not update the cputimer if the task is already >>> released by >>> + * release_task(). >>> + * >>> + * it would preferable to defer the autoreap release_task >>> + * after the last context switch but harder to do. >>> + */ >>> + if (likely(curtask->sighand)) >>> + account_group_exec_runtime(curtask, delta_exec); >>> } >> >> I'm confused. glibc's rt/tst-cputimer1 doesn't have thread exiting code. I >> have >> no seen any issue in this accounting. > > glibc launch a helper thread to receive timer signal and will also > create a new thread upon signal reception when a timer is created with > sigev_notify = SIGEV_THREAD; > > please see: > > glibc-2.17/nptl/sysdeps/unix/sysv/linux/timer_create.c > glibc-2.17/nptl/sysdeps/unix/sysv/linux/timer_routines.c
I know. I taled thread exiting. not thread creating. And, as far as I can see, only test sig1 can fail, not thr[12]. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
