On Wed, May 4, 2016 at 2:58 AM, Wanpeng Li <kernellwp(a)gmail.com> wrote:
2016-05-03 20:15 GMT+08:00 Rafael J. Wysocki
> On Tue, May 3, 2016 at 10:32 AM, Peter Zijlstra <peterz(a)infradead.org> wrote:
>> On Tue, May 03, 2016 at 09:10:51AM +0800, kernel test robot wrote:
>>> FYI, we noticed the following commit:
>>> commit 41e0d37f7ac81297c07ba311e4ad39465b8c8295 ("sched/fair: Do not
call cpufreq hook unless util changed")
>> That's intel_pstate.c:get_avg_frequency(), which assumes mperf != 0. It
>> being 0 seems to suggest intel_pstate_sample() hasn't been called yet or
> Well, what's the tree based on?
> The mainline does this:
> bool sample_taken = intel_pstate_sample(cpu, time);
> if (sample_taken && !hwp_active)
> and (the mainline version of) intel_pstate_sample() returns false when
> it is called for the first time after setting the update_util hook.
The callsites in scheduler will set time to rq_clock(rq) when trigger
sample, so when time 0 will be used even if it is set just before
setting the update_util hook?
I'm not sure what you mean.
time=0 is special as it will cause intel_pstate_sample() to return
false on the next invocation.