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cpufreq: intel_pstate: Keep values in aperf/mperf in full precision

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Currently we shift right aperf and mperf variables by FRAC_BITS
to prevent overflow when we convert them to fix point numbers
(shift left by FRAC_BITS).

But this is not necessary, because we actually use delta aperf and mperf
which are much less than APERF and MPERF values.

So, use the unmodified APERF and MPERF values in calculation.
This also adds 8 bits in precision, although the gain is insignificant.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Stratos Karafotis 2014-07-18 08:37:25 -07:00 committed by Rafael J. Wysocki
parent 4ab60c3f32
commit ac658131d7
1 changed files with 0 additions and 3 deletions
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3
drivers/cpufreq/intel_pstate.c
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@ -584,9 +584,6 @@ static inline void intel_pstate_sample(struct cpudata *cpu)
rdmsrl(MSR_IA32_MPERF, mperf);
local_irq_restore(flags);
aperf = aperf >> FRAC_BITS;
mperf = mperf >> FRAC_BITS;
cpu->last_sample_time = cpu->sample.time;
cpu->sample.time = ktime_get();
cpu->sample.aperf = aperf;