On Wed, Jun 12, 2013 at 04:02:36PM +0200, Frederic Weisbecker wrote: > When the watchdog runs, it prevents the full dynticks > CPUs from stopping their tick because the hard lockup > detector uses perf events internally, which in turn > rely on the periodic tick. > > Since this is a rather confusing behaviour that is not > easy to track down and identify for those who want to > test CONFIG_NO_HZ_FULL, let's default disable the > watchdog on boot time when full dynticks is enabled. > > The user can still enable it later on runtime using > proc or sysctl.
I thought we had a conversation awhile ago, where we agreed this was going to be fixed for 3.11? Didn't Peter find the patch and apply it to his tree? I am confused why this is still needed? Cheers, Don > > Reported-by: Steven Rostedt <[email protected]> > Suggested-by: Peter Zijlstra <[email protected]> > Signed-off-by: Frederic Weisbecker <[email protected]> > Cc: Steven Rostedt <[email protected]> > Cc: Paul E. McKenney <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Li Zhong <[email protected]> > Cc: Don Zickus <[email protected]> > Cc: Srivatsa S. Bhat <[email protected]> > Cc: Anish Singh <[email protected]> > --- > kernel/watchdog.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/kernel/watchdog.c b/kernel/watchdog.c > index 52c9a9b..277d713 100644 > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -553,6 +553,14 @@ void __init lockup_detector_init(void) > { > set_sample_period(); > > +#ifdef CONFIG_NO_HZ_FULL > + if (watchdog_enabled) { > + watchdog_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_enabled) > watchdog_enable_all_cpus(); > } > -- > 1.7.5.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
