On Wed, Jun 21, 2017 at 05:12:06PM +0200, Thomas Gleixner wrote: > On Wed, 21 Jun 2017, kan.li...@intel.com wrote: > > > > #ifdef CONFIG_HARDLOCKUP_DETECTOR > > +/* > > + * The NMI watchdog relies on PERF_COUNT_HW_CPU_CYCLES event, which > > + * can tick faster than the measured CPU Frequency due to Turbo mode. > > + * That can lead to spurious timeouts. > > + * To workaround the issue, extending the period by 3 times. > > + */ > > u64 hw_nmi_get_sample_period(int watchdog_thresh) > > { > > - return (u64)(cpu_khz) * 1000 * watchdog_thresh; > > + return (u64)(cpu_khz) * 1000 * watchdog_thresh * 3; > > The maximum turbo frequency of any given machine can be retrieved.
Not reliably, e.g. not in virtualization. Also it would require model specific checks, so as soon as you have a new model and an old kernel it could still randomly fail. -Andi