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intel_pstate: Improve initial busy calculation

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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: Doug Smythies <dsmythies@telus.net>
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:
Doug Smythies 2014-05-30 10:10:57 -07:00 • committed by Rafael J. Wysocki
parent c4ee841f60
commit bf8102228a
1 changed files with 8 additions and 5 deletions
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13
drivers/cpufreq/intel_pstate.c
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@ -563,16 +563,19 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
static inline void intel_pstate_calc_busy(struct cpudata *cpu, static inline void intel_pstate_calc_busy(struct cpudata *cpu,
struct sample *sample) struct sample *sample)
{ {
int32_t core_pct; int64_t core_pct;
int32_t rem;
core_pct = div_fp(int_tofp((sample->aperf)), core_pct = int_tofp(sample->aperf) * int_tofp(100);
int_tofp((sample->mperf))); core_pct = div_u64_rem(core_pct, int_tofp(sample->mperf), &rem);
core_pct = mul_fp(core_pct, int_tofp(100));
if ((rem << 1) >= int_tofp(sample->mperf))
core_pct += 1;
sample->freq = fp_toint( sample->freq = fp_toint(
mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct)); 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) static inline void intel_pstate_sample(struct cpudata *cpu)