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SubjectRe: [patch] fix the softlockup watchdog to actually work
On Wed, 25 Jul 2007 11:04:39 +0200 Ingo Molnar <mingo@elte.hu> wrote:

> > fix-the-softlockup-watchdog-to-actually-work.patch
> > softlockup-make-asm-irq_regsh-available-on-every-platform.patch
> > softlockup-improve-debug-output.patch
> > softlockup-watchdog-style-cleanups.patch
> > softlockup-add-a-proc-tuning-parameter.patch
> > softlockup-add-a-proc-tuning-parameter-fix.patch
>
> you have the key one missing i think - attached below.
>
> Ingo
>
> ------------------------------------>
> Subject: softlockup: use cpu_clock() instead of sched_clock()
> From: Ingo Molnar <mingo@elte.hu>
>
> sched_clock() is not a reliable time-source, use cpu_clock() instead.
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> kernel/softlockup.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> Index: linux/kernel/softlockup.c
> ===================================================================
> --- linux.orig/kernel/softlockup.c
> +++ linux/kernel/softlockup.c
> @@ -42,14 +42,16 @@ static struct notifier_block panic_block
> * resolution, and we don't need to waste time with a big divide when
> * 2^30ns == 1.074s.
> */
> -static unsigned long get_timestamp(void)
> +static unsigned long get_timestamp(int this_cpu)
> {
> - return sched_clock() >> 30; /* 2^30 ~= 10^9 */
> + return cpu_clock(this_cpu) >> 30; /* 2^30 ~= 10^9 */
> }
>
> void touch_softlockup_watchdog(void)
> {
> - __raw_get_cpu_var(touch_timestamp) = get_timestamp();
> + int this_cpu = raw_smp_processor_id();
> +
> + per_cpu(touch_timestamp, this_cpu) = get_timestamp(this_cpu);
> }
> EXPORT_SYMBOL(touch_softlockup_watchdog);
>
> @@ -95,7 +97,7 @@ void softlockup_tick(void)
> return;

argh. afacit this was never sent, except as part of some jumbopatch called
"sched: implement cpu_clock(cpu) high-speed time source".

That patch helped.

It's all a plot.

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