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Commit 21ca6d2c authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: schedutil: Add iowait boosting 



Modify the schedutil cpufreq governor to boost the CPU
frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to
it via cpufreq_update_util().

If that happens, the frequency is set to the maximum during
the first update after receiving the SCHED_CPUFREQ_IOWAIT flag
and then the boost is reduced by half during each following update.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Looks-good-to: Steve Muckle <smuckle@linaro.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 8c34ab19

kernel/sched/cpufreq_schedutil.c

+49 −4
Original line number Diff line number Diff line
@@ -47,11 +47,13 @@ struct sugov_cpu { 
	struct sugov_policy *sg_policy;



	unsigned int cached_raw_freq;

	unsigned long iowait_boost;

	unsigned long iowait_boost_max;

	u64 last_update;



	/* The fields below are only needed when sharing a policy. */

	unsigned long util;

	unsigned long max;

	u64 last_update;

	unsigned int flags;

};
@@ -155,6 +157,36 @@ static void sugov_get_util(unsigned long *util, unsigned long *max) 
	*max = cfs_max;

}



static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,

				   unsigned int flags)

{

	if (flags & SCHED_CPUFREQ_IOWAIT) {

		sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;

	} else if (sg_cpu->iowait_boost) {

		s64 delta_ns = time - sg_cpu->last_update;



		/* Clear iowait_boost if the CPU apprears to have been idle. */

		if (delta_ns > TICK_NSEC)

			sg_cpu->iowait_boost = 0;

	}

}



static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,

			       unsigned long *max)

{

	unsigned long boost_util = sg_cpu->iowait_boost;

	unsigned long boost_max = sg_cpu->iowait_boost_max;



	if (!boost_util)

		return;



	if (*util * boost_max < *max * boost_util) {

		*util = boost_util;

		*max = boost_max;

	}

	sg_cpu->iowait_boost >>= 1;

}



static void sugov_update_single(struct update_util_data *hook, u64 time,

				unsigned int flags)

{
@@ -164,6 +196,9 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, 
	unsigned long util, max;

	unsigned int next_f;



	sugov_set_iowait_boost(sg_cpu, time, flags);

	sg_cpu->last_update = time;



	if (!sugov_should_update_freq(sg_policy, time))

		return;
@@ -171,6 +206,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, 
		next_f = policy->cpuinfo.max_freq;

	} else {

		sugov_get_util(&util, &max);

		sugov_iowait_boost(sg_cpu, &util, &max);

		next_f = get_next_freq(sg_cpu, util, max);

	}

	sugov_update_commit(sg_policy, time, next_f);
@@ -189,6 +225,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, 
	if (flags & SCHED_CPUFREQ_RT_DL)

		return max_f;



	sugov_iowait_boost(sg_cpu, &util, &max);



	for_each_cpu(j, policy->cpus) {

		struct sugov_cpu *j_sg_cpu;

		unsigned long j_util, j_max;
@@ -203,12 +241,13 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, 
		 * frequency update and the time elapsed between the last update

		 * of the CPU utilization and the last frequency update is long

		 * enough, don't take the CPU into account as it probably is

		 * idle now.

		 * idle now (and clear iowait_boost for it).

		 */

		delta_ns = last_freq_update_time - j_sg_cpu->last_update;

		if (delta_ns > TICK_NSEC)

		if (delta_ns > TICK_NSEC) {

			j_sg_cpu->iowait_boost = 0;

			continue;



		}

		if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)

			return max_f;
@@ -218,6 +257,8 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, 
			util = j_util;

			max = j_max;

		}



		sugov_iowait_boost(j_sg_cpu, &util, &max);

	}



	return get_next_freq(sg_cpu, util, max);
@@ -238,6 +279,8 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, 
	sg_cpu->util = util;

	sg_cpu->max = max;

	sg_cpu->flags = flags;



	sugov_set_iowait_boost(sg_cpu, time, flags);

	sg_cpu->last_update = time;



	if (sugov_should_update_freq(sg_policy, time)) {
@@ -470,6 +513,8 @@ static int sugov_start(struct cpufreq_policy *policy) 
			sg_cpu->flags = SCHED_CPUFREQ_RT;

			sg_cpu->last_update = 0;

			sg_cpu->cached_raw_freq = 0;

			sg_cpu->iowait_boost = 0;

			sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;

			cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,

						     sugov_update_shared);

		} else {