From bf8102228a8bf053051f311e5486042fe0542894 Mon Sep 17 00:00:00 2001 From: Doug Smythies Date: Fri, 30 May 2014 10:10:57 -0700 Subject: 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+ # 3.14+ Signed-off-by: Doug Smythies Signed-off-by: Dirk Brandewie Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 2a07588..db2e45b 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -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) -- cgit v1.1