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Commit 1aa7a6e2 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

intel_pstate: Clean up get_target_pstate_use_performance() 



The comments and the core_busy variable name in
get_target_pstate_use_performance() are totally confusing,
so modify them to reflect what's going on.

The results of the computations should be the same as before.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 8edb0a6e

drivers/cpufreq/intel_pstate.c

+11 −16
Original line number Diff line number Diff line
@@ -1259,43 +1259,38 @@ static inline int32_t get_target_pstate_use_cpu_load(struct cpudata *cpu) 


static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)

{

	int32_t core_busy, max_pstate, current_pstate, sample_ratio;

	int32_t perf_scaled, max_pstate, current_pstate, sample_ratio;

	u64 duration_ns;



	/*

	 * core_busy is the ratio of actual performance to max

	 * max_pstate is the max non turbo pstate available

	 * current_pstate was the pstate that was requested during

	 * 	the last sample period.

	 *

	 * We normalize core_busy, which was our actual percent

	 * performance to what we requested during the last sample

	 * period. The result will be a percentage of busy at a

	 * specified pstate.

	 * perf_scaled is the average performance during the last sampling

	 * period scaled by the ratio of the maximum P-state to the P-state

	 * requested last time (in percent).  That measures the system's

	 * response to the previous P-state selection.

	 */

	max_pstate = cpu->pstate.max_pstate_physical;

	current_pstate = cpu->pstate.current_pstate;

	core_busy = mul_ext_fp(cpu->sample.core_avg_perf,

	perf_scaled = mul_ext_fp(cpu->sample.core_avg_perf,

			       div_fp(100 * max_pstate, current_pstate));



	/*

	 * Since our utilization update callback will not run unless we are

	 * in C0, check if the actual elapsed time is significantly greater (3x)

	 * than our sample interval.  If it is, then we were idle for a long

	 * enough period of time to adjust our busyness.

	 * enough period of time to adjust our performance metric.

	 */

	duration_ns = cpu->sample.time - cpu->last_sample_time;

	if ((s64)duration_ns > pid_params.sample_rate_ns * 3) {

		sample_ratio = div_fp(pid_params.sample_rate_ns, duration_ns);

		core_busy = mul_fp(core_busy, sample_ratio);

		perf_scaled = mul_fp(perf_scaled, sample_ratio);

	} else {

		sample_ratio = div_fp(100 * cpu->sample.mperf, cpu->sample.tsc);

		if (sample_ratio < int_tofp(1))

			core_busy = 0;

			perf_scaled = 0;

	}



	cpu->sample.busy_scaled = core_busy;

	return cpu->pstate.current_pstate - pid_calc(&cpu->pid, core_busy);

	cpu->sample.busy_scaled = perf_scaled;

	return cpu->pstate.current_pstate - pid_calc(&cpu->pid, perf_scaled);

}



static inline void intel_pstate_update_pstate(struct cpudata *cpu, int pstate)