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Commit e3126a01 authored by Morten Rasmussen's avatar Morten Rasmussen Committed by Chris Redpath
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ANDROID: sched: Extend sched_group_energy to test load-balancing decisions 



Extended sched_group_energy() to support energy prediction with usage
(tasks) added/removed from a specific cpu or migrated between a pair of
cpus. Useful for load-balancing decision making.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarMorten Rasmussen <morten.rasmussen@arm.com>
Change-Id: I31afd581448d894a97afa7f5f7dac4666191e6a0
Signed-off-by: default avatarChris Redpath <chris.redpath@arm.com>
parent 3ae1b070

kernel/sched/fair.c

+68 −30
Original line number Diff line number Diff line
@@ -5336,12 +5336,21 @@ static unsigned long cpu_avg_load_per_task(int cpu) 
 * capacity_orig) as it useful for predicting the capacity required after task

 * migrations (scheduler-driven DVFS).

 */

static unsigned long cpu_util(int cpu)

static unsigned long __cpu_util(int cpu, int delta)

{

	unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg;

	unsigned long capacity = capacity_orig_of(cpu);



	return (util >= capacity) ? capacity : util;

	delta += util;

	if (delta < 0)

		return 0;



	return (delta >= capacity) ? capacity : delta;

}



static unsigned long cpu_util(int cpu)

{

	return __cpu_util(cpu, 0);

}



static void record_wakee(struct task_struct *p)
@@ -5366,8 +5375,18 @@ static inline bool energy_aware(void) 
	return sched_feat(ENERGY_AWARE);

}



struct energy_env {

	struct sched_group	*sg_top;

	struct sched_group	*sg_cap;

	int			cap_idx;

	int			util_delta;

	int			src_cpu;

	int			dst_cpu;

	int			energy;

};



/*

 * cpu_norm_util() returns the cpu util relative to a specific capacity,

 * __cpu_norm_util() returns the cpu util relative to a specific capacity,

 * i.e. it's busy ratio, in the range [0..SCHED_CAPACITY_SCALE] which is useful

 * for energy calculations. Using the scale-invariant util returned by

 * cpu_util() and approximating scale-invariant util by:
@@ -5380,9 +5399,9 @@ static inline bool energy_aware(void) 
 *

 *   norm_util = running_time/time ~ util/capacity

 */

static unsigned long cpu_norm_util(int cpu, unsigned long capacity)

static unsigned long __cpu_norm_util(int cpu, unsigned long capacity, int delta)

{

	int util = cpu_util(cpu);

	int util = __cpu_util(cpu, delta);



	if (util >= capacity)

		return SCHED_CAPACITY_SCALE;
@@ -5390,13 +5409,25 @@ static unsigned long cpu_norm_util(int cpu, unsigned long capacity) 
	return (util << SCHED_CAPACITY_SHIFT)/capacity;

}



static unsigned long group_max_util(struct sched_group *sg)

static int calc_util_delta(struct energy_env *eenv, int cpu)

{

	int i;

	if (cpu == eenv->src_cpu)

		return -eenv->util_delta;

	if (cpu == eenv->dst_cpu)

		return eenv->util_delta;

	return 0;

}



static

unsigned long group_max_util(struct energy_env *eenv)

{

	int i, delta;

	unsigned long max_util = 0;



	for_each_cpu(i, sched_group_span(sg))

		max_util = max(max_util, cpu_util(i));

	for_each_cpu(i, sched_group_span(eenv->sg_cap)) {

		delta = calc_util_delta(eenv, i);

		max_util = max(max_util, __cpu_util(i, delta));

	}



	return max_util;

}
@@ -5410,32 +5441,39 @@ static unsigned long group_max_util(struct sched_group *sg) 
 * latter is used as the estimate as it leads to a more pessimistic energy

 * estimate (more busy).

 */

static unsigned long group_norm_util(struct sched_group *sg, int cap_idx)

static unsigned

long group_norm_util(struct energy_env *eenv, struct sched_group *sg)

{

	int i;

	int i, delta;

	unsigned long util_sum = 0;

	unsigned long capacity = sg->sge->cap_states[cap_idx].cap;

	unsigned long capacity = sg->sge->cap_states[eenv->cap_idx].cap;



	for_each_cpu(i, sched_group_span(sg))

		util_sum += cpu_norm_util(i, capacity);

	for_each_cpu(i, sched_group_span(sg)) {

		delta = calc_util_delta(eenv, i);

		util_sum += __cpu_norm_util(i, capacity, delta);

	}



	if (util_sum > SCHED_CAPACITY_SCALE)

		return SCHED_CAPACITY_SCALE;

	return util_sum;

}



static int find_new_capacity(struct sched_group *sg,

static int find_new_capacity(struct energy_env *eenv,

	const struct sched_group_energy const *sge)

{

	int idx = sge->nr_cap_states - 1;

	unsigned long util = group_max_util(sg);

	int idx;

	unsigned long util = group_max_util(eenv);



	eenv->cap_idx = sge->nr_cap_states - 1;



	for (idx = 0; idx < sge->nr_cap_states; idx++) {

		if (sge->cap_states[idx].cap >= util)

			return idx;

		if (sge->cap_states[idx].cap >= util) {

			eenv->cap_idx = idx;

			break;

		}

	}



	return idx;

	return eenv->cap_idx;

}



/*
@@ -5448,16 +5486,16 @@ static int find_new_capacity(struct sched_group *sg, 
 * This can probably be done in a faster but more complex way.

 * Note: sched_group_energy() may fail when racing with sched_domain updates.

 */

static int sched_group_energy(struct sched_group *sg_top)

static int sched_group_energy(struct energy_env *eenv)

{

	struct sched_domain *sd;

	int cpu, total_energy = 0;

	struct cpumask visit_cpus;

	struct sched_group *sg;



	WARN_ON(!sg_top->sge);

	WARN_ON(!eenv->sg_top->sge);



	cpumask_copy(&visit_cpus, sched_group_span(sg_top));

	cpumask_copy(&visit_cpus, sched_group_span(eenv->sg_top));



	while (!cpumask_empty(&visit_cpus)) {

		struct sched_group *sg_shared_cap = NULL;
@@ -5489,17 +5527,16 @@ static int sched_group_energy(struct sched_group *sg_top) 
				break;



			do {

				struct sched_group *sg_cap_util;

				unsigned long group_util;

				int sg_busy_energy, sg_idle_energy, cap_idx;



				if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight)

					sg_cap_util = sg_shared_cap;

					eenv->sg_cap = sg_shared_cap;

				else

					sg_cap_util = sg;

					eenv->sg_cap = sg;



				cap_idx = find_new_capacity(sg_cap_util, sg->sge);

				group_util = group_norm_util(sg, cap_idx);

				cap_idx = find_new_capacity(eenv, sg->sge);

				group_util = group_norm_util(eenv, sg);

				sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power)

										>> SCHED_CAPACITY_SHIFT;

				sg_idle_energy = ((SCHED_CAPACITY_SCALE-group_util) * sg->sge->idle_states[0].power)
@@ -5510,7 +5547,7 @@ static int sched_group_energy(struct sched_group *sg_top) 
				if (!sd->child)

					cpumask_xor(&visit_cpus, &visit_cpus, sched_group_span(sg));



				if (cpumask_equal(sched_group_span(sg), sched_group_span(sg_top)))

				if (cpumask_equal(sched_group_span(sg), sched_group_span(eenv->sg_top)))

					goto next_cpu;



			} while (sg = sg->next, sg != sd->groups);
@@ -5519,7 +5556,8 @@ static int sched_group_energy(struct sched_group *sg_top) 
		continue;

	}



	return total_energy;

	eenv->energy = total_energy;

	return 0;

}



/*