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| author | Doug Smythies <dsmythies@telus.net> | 2014-05-30 10:10:57 -0700 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-06-02 12:46:01 +0200 |
| commit | bf8102228a8bf053051f311e5486042fe0542894 (patch) | |
| tree | 67c29987588de6d24200039ac1574f8af9c6a301 /drivers/cpufreq | |
| parent | c4ee841f602e5eef8eab673295c49c5b49d7732b (diff) | |
| download | lwn-bf8102228a8bf053051f311e5486042fe0542894.tar.gz lwn-bf8102228a8bf053051f311e5486042fe0542894.zip | |
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: 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>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 2a07588dcbac..db2e45b4808e 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) |