Messages in this thread Patch in this message | | | Date | Tue, 20 Nov 2007 09:46:11 +0100 | From | Ingo Molnar <> | Subject | [patch] softlockup: do the wakeup from a hrtimer |
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Subject: softlockup: do the wakeup from a hrtimer From: Ingo Molnar <mingo@elte.hu>
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 <davem@davemloft.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- 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 majordomo@vger.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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