The patch titled From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> has been added to the -mm tree. Its filename is posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> When process delete cpu timer or timer expires we do not clear expiration cache sig->cputimer_expires. This create situation when in fastpath_timer_check() we _on_ cputimer (together with loop on all threads) just to turn in off in check_process_timers(). We not necessary go to slowpath and not necessary loop on all threads in fastpath - and this is repeated on every tick. To fix we zero sig->cputimer_expires in stop_process_timers(). Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx> Cc: Spencer Candland <spencer@xxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/posix-cpu-timers.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff -puN kernel/posix-cpu-timers.c~posix-cpu-timers-reset-expire-cache-when-no-timer-is-running kernel/posix-cpu-timers.c --- a/kernel/posix-cpu-timers.c~posix-cpu-timers-reset-expire-cache-when-no-timer-is-running +++ a/kernel/posix-cpu-timers.c @@ -1060,9 +1060,9 @@ static void check_thread_timers(struct t } } -static void stop_process_timers(struct task_struct *tsk) +static void stop_process_timers(struct signal_struct *sig) { - struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; + struct thread_group_cputimer *cputimer = &sig->cputimer; unsigned long flags; if (!cputimer->running) @@ -1071,6 +1071,10 @@ static void stop_process_timers(struct t spin_lock_irqsave(&cputimer->lock, flags); cputimer->running = 0; spin_unlock_irqrestore(&cputimer->lock, flags); + + sig->cputime_expires.prof_exp = cputime_zero; + sig->cputime_expires.virt_exp = cputime_zero; + sig->cputime_expires.sched_exp = 0; } static u32 onecputick; @@ -1131,7 +1135,7 @@ static void check_process_timers(struct list_empty(&timers[CPUCLOCK_VIRT]) && cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) && list_empty(&timers[CPUCLOCK_SCHED])) { - stop_process_timers(tsk); + stop_process_timers(sig); return; } _ Patches currently in -mm which might be from sgruszka@xxxxxxxxxx are linux-next.patch itimers-fix-racy-writes-to-cpu_itimer-fields.patch posix-cpu-timers-optimize-and-document-timer_create-callback.patch posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html