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Commit 09c448d3 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: intel_pstate: Use IOWAIT flag in Atom algorithm 



Modify the P-state selection algorithm for Atom processors to use
the new SCHED_CPUFREQ_IOWAIT flag instead of the questionable
get_cpu_iowait_time_us() function.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 21ca6d2c

drivers/cpufreq/intel_pstate.c

+31 −27
Original line number Diff line number Diff line
@@ -181,6 +181,8 @@ struct _pid { 
 * @cpu:		CPU number for this instance data

 * @update_util:	CPUFreq utility callback information

 * @update_util_set:	CPUFreq utility callback is set

 * @iowait_boost:	iowait-related boost fraction

 * @last_update:	Time of the last update.

 * @pstate:		Stores P state limits for this CPU

 * @vid:		Stores VID limits for this CPU

 * @pid:		Stores PID parameters for this CPU
@@ -206,6 +208,7 @@ struct cpudata { 
	struct vid_data vid;

	struct _pid pid;



	u64	last_update;

	u64	last_sample_time;

	u64	prev_aperf;

	u64	prev_mperf;
@@ -216,6 +219,7 @@ struct cpudata { 
	struct acpi_processor_performance acpi_perf_data;

	bool valid_pss_table;

#endif

	unsigned int iowait_boost;

};



static struct cpudata **all_cpu_data;
@@ -229,6 +233,7 @@ static struct cpudata **all_cpu_data; 
 * @p_gain_pct:		PID proportional gain

 * @i_gain_pct:		PID integral gain

 * @d_gain_pct:		PID derivative gain

 * @boost_iowait:	Whether or not to use iowait boosting.

 *

 * Stores per CPU model static PID configuration data.

 */
@@ -240,6 +245,7 @@ struct pstate_adjust_policy { 
	int p_gain_pct;

	int d_gain_pct;

	int i_gain_pct;

	bool boost_iowait;

};



/**
@@ -1037,6 +1043,7 @@ static struct cpu_defaults silvermont_params = { 
		.p_gain_pct = 14,

		.d_gain_pct = 0,

		.i_gain_pct = 4,

		.boost_iowait = true,

	},

	.funcs = {

		.get_max = atom_get_max_pstate,
@@ -1058,6 +1065,7 @@ static struct cpu_defaults airmont_params = { 
		.p_gain_pct = 14,

		.d_gain_pct = 0,

		.i_gain_pct = 4,

		.boost_iowait = true,

	},

	.funcs = {

		.get_max = atom_get_max_pstate,
@@ -1099,6 +1107,7 @@ static struct cpu_defaults bxt_params = { 
		.p_gain_pct = 14,

		.d_gain_pct = 0,

		.i_gain_pct = 4,

		.boost_iowait = true,

	},

	.funcs = {

		.get_max = core_get_max_pstate,
@@ -1222,36 +1231,18 @@ static inline int32_t get_avg_pstate(struct cpudata *cpu) 
static inline int32_t get_target_pstate_use_cpu_load(struct cpudata *cpu)

{

	struct sample *sample = &cpu->sample;

	u64 cummulative_iowait, delta_iowait_us;

	u64 delta_iowait_mperf;

	u64 mperf, now;

	int32_t cpu_load;

	int32_t busy_frac, boost;



	cummulative_iowait = get_cpu_iowait_time_us(cpu->cpu, &now);

	busy_frac = div_fp(sample->mperf, sample->tsc);



	/*

	 * Convert iowait time into number of IO cycles spent at max_freq.

	 * IO is considered as busy only for the cpu_load algorithm. For

	 * performance this is not needed since we always try to reach the

	 * maximum P-State, so we are already boosting the IOs.

	 */

	delta_iowait_us = cummulative_iowait - cpu->prev_cummulative_iowait;

	delta_iowait_mperf = div64_u64(delta_iowait_us * cpu->pstate.scaling *

		cpu->pstate.max_pstate, MSEC_PER_SEC);

	boost = cpu->iowait_boost;

	cpu->iowait_boost >>= 1;



	mperf = cpu->sample.mperf + delta_iowait_mperf;

	cpu->prev_cummulative_iowait = cummulative_iowait;



	/*

	 * The load can be estimated as the ratio of the mperf counter

	 * running at a constant frequency during active periods

	 * (C0) and the time stamp counter running at the same frequency

	 * also during C-states.

	 */

	cpu_load = div64_u64(int_tofp(100) * mperf, sample->tsc);

	cpu->sample.busy_scaled = cpu_load;

	if (busy_frac < boost)

		busy_frac = boost;



	return get_avg_pstate(cpu) - pid_calc(&cpu->pid, cpu_load);

	sample->busy_scaled = busy_frac * 100;

	return get_avg_pstate(cpu) - pid_calc(&cpu->pid, sample->busy_scaled);

}



static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
@@ -1332,8 +1323,21 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time, 
				     unsigned int flags)

{

	struct cpudata *cpu = container_of(data, struct cpudata, update_util);

	u64 delta_ns = time - cpu->sample.time;

	u64 delta_ns;



	if (pid_params.boost_iowait) {

		if (flags & SCHED_CPUFREQ_IOWAIT) {

			cpu->iowait_boost = int_tofp(1);

		} else if (cpu->iowait_boost) {

			/* Clear iowait_boost if the CPU may have been idle. */

			delta_ns = time - cpu->last_update;

			if (delta_ns > TICK_NSEC)

				cpu->iowait_boost = 0;

		}

		cpu->last_update = time;

	}



	delta_ns = time - cpu->sample.time;

	if ((s64)delta_ns >= pid_params.sample_rate_ns) {

		bool sample_taken = intel_pstate_sample(cpu, time);