Messages in this thread Patch in this message | | | From | Johannes Weiner <> | Subject | Re: [PATCH 3/3] softlockup: fix watchdog task wakeup frequency | Date | Fri, 27 Jun 2008 14:33:40 +0200 |
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Ingo Molnar <mingo@elte.hu> writes:
> * Johannes Weiner <hannes@saeurebad.de> wrote: > >> Wake up the watchdog every second instead of every second. [...] > > now _that_ is a real improvement ;-) > >> /* Wake up the high-prio watchdog task every second: */ >> - if (now > (touch_timestamp + 1)) >> + if (now > touch_timestamp) >> wake_up_process(per_cpu(watchdog_task, this_cpu)); > > you mean wake up every second instead of every two seconds?
Every second second :D The second `second' [adjective] refers to the first `second' [noun].
> i think the best sleep period for the watchdog is half of the threshold. > It makes no point to check sooner than that. I.e. softlockup_thresh/2 > would be better?
Hm, it updates the timestamp, so it makes only sense if it runs at a maximum every second (timestamp granularity) or even less. The check for hung tasks uses the cpu timestamp as well for comparison, so that would be okay too.
Like this?
diff --git a/kernel/softlockup.c b/kernel/softlockup.c index c828c23..b884546 100644 --- a/kernel/softlockup.c +++ b/kernel/softlockup.c @@ -106,8 +106,9 @@ 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 the high-prio watchdog task twice per + * threshold timespan. */ + if (now > (touch_timestamp + softlockup_thresh / 2)) wake_up_process(per_cpu(watchdog_task, this_cpu)); /* Warn about unreasonable delays: */
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