From 4fec7ad5f637159525265a45f66482cf8817b45f Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 10 Mar 2016 23:45:19 +0100 Subject: [PATCH] intel_pstate: Do not skip samples partially If the current value of MPERF or the current value of TSC is the same as the previous one, respectively, intel_pstate_sample() bails out early and skips the sample. However, intel_pstate_adjust_busy_pstate() is still called in that case which is not correct, so modify intel_pstate_sample() to return a bool value indicating whether or not the sample has been taken and use it to decide whether or not to call intel_pstate_adjust_busy_pstate(). While at it, remove redundant parentheses from the MPERF/TSC check in intel_pstate_sample(). Signed-off-by: Rafael J. Wysocki Acked-by: Srinivas Pandruvada --- drivers/cpufreq/intel_pstate.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 4acb904908d1..cb5607495816 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -884,7 +884,7 @@ static inline void intel_pstate_calc_busy(struct cpudata *cpu) sample->core_pct_busy = (int32_t)core_pct; } -static inline void intel_pstate_sample(struct cpudata *cpu, u64 time) +static inline bool intel_pstate_sample(struct cpudata *cpu, u64 time) { u64 aperf, mperf; unsigned long flags; @@ -894,9 +894,9 @@ static inline void intel_pstate_sample(struct cpudata *cpu, u64 time) rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); tsc = rdtsc(); - if ((cpu->prev_mperf == mperf) || (cpu->prev_tsc == tsc)) { + if (cpu->prev_mperf == mperf || cpu->prev_tsc == tsc) { local_irq_restore(flags); - return; + return false; } local_irq_restore(flags); @@ -912,6 +912,7 @@ static inline void intel_pstate_sample(struct cpudata *cpu, u64 time) cpu->prev_aperf = aperf; cpu->prev_mperf = mperf; cpu->prev_tsc = tsc; + return true; } static inline int32_t get_avg_frequency(struct cpudata *cpu) @@ -1025,8 +1026,9 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time, u64 delta_ns = time - cpu->sample.time; if ((s64)delta_ns >= pid_params.sample_rate_ns) { - intel_pstate_sample(cpu, time); - if (!hwp_active) + bool sample_taken = intel_pstate_sample(cpu, time); + + if (sample_taken && !hwp_active) intel_pstate_adjust_busy_pstate(cpu); } } -- 2.20.1