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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-03-10 23:45:19 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-03-11 00:07:51 +0100
commit4fec7ad5f637159525265a45f66482cf8817b45f (patch)
tree6896e57cde6e27fb66acdce735255b184f512a0d /drivers/cpufreq/intel_pstate.c
parent8fa520af50817d5f30d293f507c937f561b3e6b9 (diff)
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/intel_pstate.c')
-rw-r--r--drivers/cpufreq/intel_pstate.c12
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);
}
}