Messages in this thread | | | Date | Wed, 4 May 2016 13:44:18 +0200 | Subject | Re: [lkp] [sched/fair] 41e0d37f7a: divide error: 0000 [#1] SMP | From | "Rafael J. Wysocki" <> |
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On Wed, May 4, 2016 at 2:58 AM, Wanpeng Li <kernellwp@gmail.com> wrote: > 2016-05-03 20:15 GMT+08:00 Rafael J. Wysocki <rafael@kernel.org>: >> On Tue, May 3, 2016 at 10:32 AM, Peter Zijlstra <peterz@infradead.org> wrote: >>> On Tue, May 03, 2016 at 09:10:51AM +0800, kernel test robot wrote: >>>> FYI, we noticed the following commit: >>>> >>>> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core >>>> commit 41e0d37f7ac81297c07ba311e4ad39465b8c8295 ("sched/fair: Do not call cpufreq hook unless util changed") >>>
[cut]
>>> >>> 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 >>> so. >> >> Well, what's the tree based on? >> >> The mainline does this: >> >> bool sample_taken = intel_pstate_sample(cpu, time); >> >> if (sample_taken && !hwp_active) >> intel_pstate_adjust_busy_pstate(cpu); >> >> 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.
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