Subject: softlockup: do the wakeup from a hrtimer From: Ingo Molnar <[EMAIL PROTECTED]>
David Miller reported soft lockup false-positives that trigger on NOHZ due to CPUs idling for more than 10 seconds. The solution is to drive the wakeup of the watchdog threads not from the timer tick (which has no guaranteed frequency), but from the watchdog tasks themselves. http://bugzilla.kernel.org/show_bug.cgi?id=9409 Reported-by: David Miller <[EMAIL PROTECTED]> Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]> --- kernel/softlockup.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) Index: linux/kernel/softlockup.c =================================================================== --- linux.orig/kernel/softlockup.c +++ linux/kernel/softlockup.c @@ -100,10 +100,6 @@ void softlockup_tick(void) now = get_timestamp(this_cpu); - /* Wake up the high-prio watchdog task every second: */ - if (now > (touch_timestamp + 1)) - wake_up_process(per_cpu(watchdog_task, this_cpu)); - /* Warn about unreasonable 10+ seconds delays: */ if (now <= (touch_timestamp + softlockup_thresh)) return; @@ -141,7 +137,7 @@ static int watchdog(void *__bind_cpu) while (!kthread_should_stop()) { set_current_state(TASK_INTERRUPTIBLE); touch_softlockup_watchdog(); - schedule(); + msleep(1000); } return 0; - 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/
