intel_pstate: remove unneeded sample buffers

Remove unneeded sample buffers, intel_pstate operates on the most
recent sample only.  This save some memory and make the code more
readable.
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -99,8 +99,7 @@ struct cpudata {
 	u64	prev_aperf;
 	u64	prev_mperf;
 	unsigned long long prev_tsc;
-	int	sample_ptr;
-	struct sample samples[SAMPLE_COUNT];
+	struct sample sample;
 };
 
 static struct cpudata **all_cpu_data;
@@ -586,15 +585,14 @@ static inline void intel_pstate_sample(struct cpudata *cpu)
 	mperf = mperf >> FRAC_BITS;
 	tsc = tsc >> FRAC_BITS;
 
-	cpu->sample_ptr = (cpu->sample_ptr + 1) % SAMPLE_COUNT;
-	cpu->samples[cpu->sample_ptr].aperf = aperf;
-	cpu->samples[cpu->sample_ptr].mperf = mperf;
-	cpu->samples[cpu->sample_ptr].tsc = tsc;
-	cpu->samples[cpu->sample_ptr].aperf -= cpu->prev_aperf;
-	cpu->samples[cpu->sample_ptr].mperf -= cpu->prev_mperf;
-	cpu->samples[cpu->sample_ptr].tsc -= cpu->prev_tsc;
+	cpu->sample.aperf = aperf;
+	cpu->sample.mperf = mperf;
+	cpu->sample.tsc = tsc;
+	cpu->sample.aperf -= cpu->prev_aperf;
+	cpu->sample.mperf -= cpu->prev_mperf;
+	cpu->sample.tsc -= cpu->prev_tsc;
 
-	intel_pstate_calc_busy(cpu, &cpu->samples[cpu->sample_ptr]);
+	intel_pstate_calc_busy(cpu, &cpu->sample);
 
 	cpu->prev_aperf = aperf;
 	cpu->prev_mperf = mperf;
@@ -614,7 +612,7 @@ static inline int32_t intel_pstate_get_scaled_busy(struct cpudata *cpu)
 {
 	int32_t core_busy, max_pstate, current_pstate;
 
-	core_busy = cpu->samples[cpu->sample_ptr].core_pct_busy;
+	core_busy = cpu->sample.core_pct_busy;
 	max_pstate = int_tofp(cpu->pstate.max_pstate);
 	current_pstate = int_tofp(cpu->pstate.current_pstate);
 	core_busy = mul_fp(core_busy, div_fp(max_pstate, current_pstate));
@@ -648,7 +646,7 @@ static void intel_pstate_timer_func(unsigned long __data)
 
 	intel_pstate_sample(cpu);
 
-	sample = &cpu->samples[cpu->sample_ptr];
+	sample = &cpu->sample;
 
 	intel_pstate_adjust_busy_pstate(cpu);
 
@@ -729,7 +727,7 @@ static unsigned int intel_pstate_get(unsigned int cpu_num)
 	cpu = all_cpu_data[cpu_num];
 	if (!cpu)
 		return 0;
-	sample = &cpu->samples[cpu->sample_ptr];
+	sample = &cpu->sample;
 	return sample->freq;
 }