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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-03-10 23:45:19 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-03-11 00:07:51 +0100 |
| commit | 4fec7ad5f637159525265a45f66482cf8817b45f (patch) | |
| tree | 6896e57cde6e27fb66acdce735255b184f512a0d /drivers/cpufreq | |
| parent | 8fa520af50817d5f30d293f507c937f561b3e6b9 (diff) | |
| download | lwn-4fec7ad5f637159525265a45f66482cf8817b45f.tar.gz lwn-4fec7ad5f637159525265a45f66482cf8817b45f.zip | |
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 <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 12 |
1 files 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); } } |