Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 42503db7 authored by Srinath Sridharan's avatar Srinath Sridharan Committed by Dmitry Shmidt
Browse files

ANDROID: sched/tune: Introducing a new schedtune attribute prefer_idle 



Hint to enable biasing of tasks towards idle cpus, even when a given
task is negatively boosted. The mechanism allows upto 20% reduction in
camera power without hurting performance.

bug: 28312446
Change-Id: I97ea5671aa1e6bcb165408b41e17bc82e41c2c9e
Signed-off-by: default avatarAndres Oportus <andresoportus@google.com>
parent bd7ee31d

kernel/sched/fair.c

+13 −10
Original line number Diff line number Diff line
@@ -6289,7 +6289,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) 
	return target;

}



static inline int find_best_target(struct task_struct *p, bool boosted)

static inline int find_best_target(struct task_struct *p, bool prefer_idle)

{

	int iter_cpu;

	int target_cpu = -1;
@@ -6307,9 +6307,9 @@ static inline int find_best_target(struct task_struct *p, bool boosted) 
		int idle_idx;



		/*

		 * favor higher cpus for boosted tasks

		 * favor higher cpus for tasks that prefer idle cores

		 */

		int i = boosted ? NR_CPUS-iter_cpu-1 : iter_cpu;

		int i = prefer_idle ? NR_CPUS-iter_cpu-1 : iter_cpu;



		if (!cpu_online(i) || !cpumask_test_cpu(i, tsk_cpus_allowed(p)))

			continue;
@@ -6334,10 +6334,10 @@ static inline int find_best_target(struct task_struct *p, bool boosted) 
			continue;

#endif

		/*

		 * For boosted tasks we favor idle cpus unconditionally to

		 * Unconditionally favoring tasks that prefer idle cpus to

		 * improve latency.

		 */

		if (idle_cpu(i) && boosted) {

		if (idle_cpu(i) && prefer_idle) {

			if (best_idle_cpu < 0)

				best_idle_cpu = i;

			continue;
@@ -6354,7 +6354,7 @@ static inline int find_best_target(struct task_struct *p, bool boosted) 
					target_cpu = i;

					target_util = new_util;

				}

			} else if (!boosted) {

			} else if (!prefer_idle) {

				if (best_idle_cpu < 0 ||

					(sysctl_sched_cstate_aware &&

						best_idle_cstate > idle_idx)) {
@@ -6369,7 +6369,7 @@ static inline int find_best_target(struct task_struct *p, bool boosted) 
		}

	}



	if (boosted && best_idle_cpu >= 0)

	if (prefer_idle && best_idle_cpu >= 0)

		target_cpu = best_idle_cpu;

	else if (target_cpu < 0)

		target_cpu = best_idle_cpu >= 0 ? best_idle_cpu : backup_cpu;
@@ -6461,15 +6461,18 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync) 
		 */

#ifdef CONFIG_CGROUP_SCHEDTUNE

		bool boosted = schedtune_task_boost(p) > 0;

		bool prefer_idle = schedtune_prefer_idle(p) > 0;

#else

		bool boosted = 0;

		bool prefer_idle = 0;

#endif

		int tmp_target = find_best_target(p, boosted);

		if (tmp_target >= 0)

		int tmp_target = find_best_target(p, boosted || prefer_idle);

		if (tmp_target >= 0) {

			target_cpu = tmp_target;

			if (boosted && idle_cpu(target_cpu))

			if ((boosted || prefer_idle) && idle_cpu(target_cpu))

				return target_cpu;

		}

	}



	if (target_cpu != task_cpu(p)) {

		struct energy_env eenv = {

kernel/sched/tune.c

+42 −0
Original line number Diff line number Diff line
@@ -125,6 +125,10 @@ struct schedtune { 


	/* Performance Constraint (C) region threshold params */

	int perf_constrain_idx;



	/* Hint to bias scheduling of tasks on that SchedTune CGroup

	 * towards idle CPUs */

	int prefer_idle;

};



static inline struct schedtune *css_st(struct cgroup_subsys_state *css)
@@ -156,6 +160,7 @@ root_schedtune = { 
	.boost	= 0,

	.perf_boost_idx = 0,

	.perf_constrain_idx = 0,

	.prefer_idle = 0,

};



int
@@ -536,6 +541,38 @@ int schedtune_task_boost(struct task_struct *p) 
	return task_boost;

}



int schedtune_prefer_idle(struct task_struct *p)

{

	struct schedtune *st;

	int prefer_idle;



	/* Get prefer_idle value */

	rcu_read_lock();

	st = task_schedtune(p);

	prefer_idle = st->prefer_idle;

	rcu_read_unlock();



	return prefer_idle;

}



static u64

prefer_idle_read(struct cgroup_subsys_state *css, struct cftype *cft)

{

	struct schedtune *st = css_st(css);



	return st->prefer_idle;

}



static int

prefer_idle_write(struct cgroup_subsys_state *css, struct cftype *cft,

	    u64 prefer_idle)

{

	struct schedtune *st = css_st(css);

	st->prefer_idle = prefer_idle;



	return 0;

}



static s64

boost_read(struct cgroup_subsys_state *css, struct cftype *cft)

{
@@ -587,6 +624,11 @@ static struct cftype files[] = { 
		.read_s64 = boost_read,

		.write_s64 = boost_write,

	},

	{

		.name = "prefer_idle",

		.read_u64 = prefer_idle_read,

		.write_u64 = prefer_idle_write,

	},

	{ }	/* terminate */

};

kernel/sched/tune.h

+2 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ struct target_nrg { 
int schedtune_cpu_boost(int cpu);

int schedtune_task_boost(struct task_struct *tsk);



int schedtune_prefer_idle(struct task_struct *tsk);



void schedtune_exit_task(struct task_struct *tsk);



void schedtune_enqueue_task(struct task_struct *p, int cpu);