On Tue, Jul 23, 2013 at 02:31:06AM +0200, Frederic Weisbecker wrote:
> A perf event can be used without forcing the tick to
> stay alive if it doesn't use a frequency but a sample
> period and if it doesn't throttle (raise storm of events).
>
> Since the lockup detector neither use a perf event frequency
> nor should ever throttle due to its high period, it can now
> run concurrently with the full dynticks feature.
Thanks. Dumb question, I keep wondering if the lockup detector would be
better or worse off if it used the perf event frequency as opposed to
using a sample period? The idea is it could follow the varying cpu
frequencies better (and probably simplify some of the code too).
Acked-by: Don Zickus <dzic...@redhat.com>
>
> Signed-off-by: Frederic Weisbecker <fweis...@gmail.com>
> Cc: Jiri Olsa <jo...@redhat.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Namhyung Kim <namhy...@kernel.org>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
> Cc: Stephane Eranian <eran...@google.com>
> Cc: Don Zickus <dzic...@redhat.com>
> Cc: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com>
> Cc: Anish Singh <anish198519851...@gmail.com>
> ---
> kernel/watchdog.c | 8 --------
> 1 files changed, 0 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 1241d8c..51c4f34 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -553,14 +553,6 @@ void __init lockup_detector_init(void)
> {
> set_sample_period();
>
> -#ifdef CONFIG_NO_HZ_FULL
> - if (watchdog_user_enabled) {
> - watchdog_user_enabled = 0;
> - pr_warning("Disabled lockup detectors by default for full
> dynticks\n");
> - pr_warning("You can reactivate it with 'sysctl -w
> kernel.watchdog=1'\n");
> - }
> -#endif
> -
> if (watchdog_user_enabled)
> watchdog_enable_all_cpus();
> }
> --
> 1.7.5.4
>
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