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Message-ID: <20080627124329.GA14576@elte.hu>
Date: Fri, 27 Jun 2008 14:43:29 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Johannes Weiner <hannes@...urebad.de>
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 3/3] softlockup: fix watchdog task wakeup frequency
* Johannes Weiner <hannes@...urebad.de> wrote:
> 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));
yeah - but please use the best possible coding style. Two-line comments
should be in the:
/*
* Here we ......................
* ........................ come:
*/
... format. And the arithmetics should be:
if (now > touch_timestamp + softlockup_thresh/2)
(the unnecessary paranthesis was a small style mistake in the original
too)
Ingo
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