4.1-stable review patch. If anyone has any objections, please let me know.
------------------ From: Srinivas Pandruvada <[email protected]> commit 8e601a9f97a00bab031980de34f9a81891c1f82f upstream. This is a workaround for KNL platform, where in some cases MPERF counter will not have updated value before next read of MSR_IA32_MPERF. In this case divide by zero will occur. This change ignores current sample for busy calculation in this case. Fixes: b34ef932d79a (intel_pstate: Knights Landing support) Signed-off-by: Srinivas Pandruvada <[email protected]> Acked-by: Kristen Carlson Accardi <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/cpufreq/intel_pstate.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -761,6 +761,11 @@ static inline void intel_pstate_sample(s local_irq_save(flags); rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); + if (cpu->prev_mperf == mperf) { + local_irq_restore(flags); + return; + } + local_irq_restore(flags); cpu->last_sample_time = cpu->sample.time; -- 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/
