Commit cdcc5ef2 authored by Sam Wu's avatar Sam Wu Committed by Rafael J. Wysocki
Browse files

Revert "cpufreq: schedutil: Move max CPU capacity to sugov_policy" 



This reverts commit 6d5afdc9.

On a Pixel 6 device, it is observed that this commit increases
latency by approximately 50ms, or 20%, in migrating a task
that requires full CPU utilization from a LITTLE CPU to Fmax
on a big CPU. Reverting this change restores the latency back
to its original baseline value.

Fixes: 6d5afdc9 ("cpufreq: schedutil: Move max CPU capacity to sugov_policy")
Signed-off-by: default avatarSam Wu <wusamuel@google.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent eb708140

kernel/sched/cpufreq_schedutil.c

+15 −15
Original line number Diff line number Diff line
@@ -25,9 +25,6 @@ struct sugov_policy { 
	unsigned int		next_freq;

	unsigned int		cached_raw_freq;



	/* max CPU capacity, which is equal for all CPUs in freq. domain */

	unsigned long		max;



	/* The next fields are only needed if fast switch cannot be used: */

	struct			irq_work irq_work;

	struct			kthread_work work;
@@ -51,6 +48,7 @@ struct sugov_cpu { 


	unsigned long		util;

	unsigned long		bw_dl;

	unsigned long		max;



	/* The field below is for single-CPU policies only: */

#ifdef CONFIG_NO_HZ_COMMON
@@ -160,6 +158,7 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu) 
{

	struct rq *rq = cpu_rq(sg_cpu->cpu);



	sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);

	sg_cpu->bw_dl = cpu_bw_dl(rq);

	sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),

					  FREQUENCY_UTIL, NULL);
@@ -254,7 +253,6 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, 
 */

static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)

{

	struct sugov_policy *sg_policy = sg_cpu->sg_policy;

	unsigned long boost;



	/* No boost currently required */
@@ -282,8 +280,7 @@ static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time) 
	 * sg_cpu->util is already in capacity scale; convert iowait_boost

	 * into the same scale so we can compare.

	 */

	boost = sg_cpu->iowait_boost * sg_policy->max;

	boost >>= SCHED_CAPACITY_SHIFT;

	boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;

	boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);

	if (sg_cpu->util < boost)

		sg_cpu->util = boost;
@@ -340,7 +337,7 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time, 
	if (!sugov_update_single_common(sg_cpu, time, flags))

		return;



	next_f = get_next_freq(sg_policy, sg_cpu->util, sg_policy->max);

	next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);

	/*

	 * Do not reduce the frequency if the CPU has not been idle

	 * recently, as the reduction is likely to be premature then.
@@ -376,7 +373,6 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, 
				     unsigned int flags)

{

	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);

	struct sugov_policy *sg_policy = sg_cpu->sg_policy;

	unsigned long prev_util = sg_cpu->util;



	/*
@@ -403,8 +399,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time, 
		sg_cpu->util = prev_util;



	cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),

				   map_util_perf(sg_cpu->util),

				   sg_policy->max);

				   map_util_perf(sg_cpu->util), sg_cpu->max);



	sg_cpu->sg_policy->last_freq_update_time = time;

}
@@ -413,19 +408,25 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time) 
{

	struct sugov_policy *sg_policy = sg_cpu->sg_policy;

	struct cpufreq_policy *policy = sg_policy->policy;

	unsigned long util = 0;

	unsigned long util = 0, max = 1;

	unsigned int j;



	for_each_cpu(j, policy->cpus) {

		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);

		unsigned long j_util, j_max;



		sugov_get_util(j_sg_cpu);

		sugov_iowait_apply(j_sg_cpu, time);

		j_util = j_sg_cpu->util;

		j_max = j_sg_cpu->max;



		util = max(j_sg_cpu->util, util);

		if (j_util * max > j_max * util) {

			util = j_util;

			max = j_max;

		}

	}



	return get_next_freq(sg_policy, util, sg_policy->max);

	return get_next_freq(sg_policy, util, max);

}



static void
@@ -751,7 +752,7 @@ static int sugov_start(struct cpufreq_policy *policy) 
{

	struct sugov_policy *sg_policy = policy->governor_data;

	void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);

	unsigned int cpu = cpumask_first(policy->cpus);

	unsigned int cpu;



	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;

	sg_policy->last_freq_update_time	= 0;
@@ -759,7 +760,6 @@ static int sugov_start(struct cpufreq_policy *policy) 
	sg_policy->work_in_progress		= false;

	sg_policy->limits_changed		= false;

	sg_policy->cached_raw_freq		= 0;

	sg_policy->max				= arch_scale_cpu_capacity(cpu);



	sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);