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Commit bf810222 authored by Doug Smythies's avatar Doug Smythies Committed by Rafael J. Wysocki
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intel_pstate: Improve initial busy calculation 



This change makes the busy calculation using 64 bit math which prevents
overflow for large values of aperf/mperf.

Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: default avatarDoug Smythies <dsmythies@telus.net>
Signed-off-by: default avatarDirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent c4ee841f

drivers/cpufreq/intel_pstate.c

+8 −5
Original line number Diff line number Diff line
@@ -563,16 +563,19 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu) 
static inline void intel_pstate_calc_busy(struct cpudata *cpu,

					struct sample *sample)

{

	int32_t core_pct;

	int64_t core_pct;

	int32_t rem;



	core_pct = div_fp(int_tofp((sample->aperf)),

			int_tofp((sample->mperf)));

	core_pct = mul_fp(core_pct, int_tofp(100));

	core_pct = int_tofp(sample->aperf) * int_tofp(100);

	core_pct = div_u64_rem(core_pct, int_tofp(sample->mperf), &rem);



	if ((rem << 1) >= int_tofp(sample->mperf))

		core_pct += 1;



	sample->freq = fp_toint(

		mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct));



	sample->core_pct_busy = core_pct;

	sample->core_pct_busy = (int32_t)core_pct;

}



static inline void intel_pstate_sample(struct cpudata *cpu)