Merge "sched: Avoid needless migration" (50dee1d4) · Commits · e / devices / android_kernel_sony_msm8994

kernel/sched/core.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -3765,6 +3765,7 @@ void scheduler_tick(void)
		trigger_load_balance(rq, cpu);
		#endif
		rq_last_tick_reset(rq);
		if (curr->sched_class == &fair_sched_class)
		check_for_migration(rq, curr);
		}

kernel/sched/fair.c

+53 −14

Original line number	Diff line number	Diff line
		@@ -1712,8 +1712,38 @@ static int best_small_task_cpu(struct task_struct *p)
		return best_fallback_cpu;
		}

		#define MOVE_TO_BIG_CPU 1
		#define MOVE_TO_LITTLE_CPU 2
		#define MOVE_TO_POWER_EFFICIENT_CPU 3

		static int skip_cpu(struct task_struct *p, int cpu, int reason)
		{
		struct rq *rq = cpu_rq(cpu);
		struct rq *task_rq = task_rq(p);
		int skip = 0;

		if (!reason)
		return 0;

		switch (reason) {
		case MOVE_TO_BIG_CPU:
		skip = (rq->capacity <= task_rq->capacity);
		break;

		case MOVE_TO_LITTLE_CPU:
		skip = (rq->capacity >= task_rq->capacity);
		break;

		default:
		skip = (cpu == task_cpu(p));
		break;
		}

		return skip;
		}

		/* return cheapest cpu that can fit this task */
		static int select_best_cpu(struct task_struct *p, int target)
		static int select_best_cpu(struct task_struct *p, int target, int reason)
		{
		int i, best_cpu = -1, fallback_idle_cpu = -1;
		int prev_cpu = task_cpu(p);
		@@ -1730,6 +1760,10 @@ static int select_best_cpu(struct task_struct *p, int target)

		/* Todo : Optimize this loop */
		for_each_cpu_and(i, tsk_cpus_allowed(p), cpu_online_mask) {

		if (skip_cpu(p, i, reason))
		continue;

		trace_sched_cpu_load(cpu_rq(i), idle_cpu(i),
		mostly_idle_cpu(i), power_cost(p, i));

		@@ -2007,10 +2041,11 @@ static int lower_power_cpu_available(struct task_struct *p, int cpu)
		return (lowest_power_cpu != task_cpu(p));
		}


		/*
		* Check if a task is on the "wrong" cpu (i.e its current cpu is not the ideal
		* cpu as per its demand or priority)
		*
		* Returns reason why task needs to be migrated
		*/
		static inline int migration_needed(struct rq rq, struct task_struct p)
		{
		@@ -2019,8 +2054,12 @@ static inline int migration_needed(struct rq rq, struct task_struct p)
		if (!sched_enable_hmp \|\| p->state != TASK_RUNNING)
		return 0;

		if (sched_boost())
		return (rq->capacity != max_capacity);
		if (sched_boost()) {
		if (rq->capacity != max_capacity)
		return MOVE_TO_BIG_CPU;

		return 0;
		}

		if (is_small_task(p))
		return 0;
		@@ -2028,21 +2067,20 @@ static inline int migration_needed(struct rq rq, struct task_struct p)
		/* Todo: cgroup-based control? */
		if (nice > sysctl_sched_upmigrate_min_nice &&
		rq->capacity > min_capacity)
		return 1;
		return MOVE_TO_LITTLE_CPU;

		if (!task_will_fit(p, cpu_of(rq)))
		return 1;
		return MOVE_TO_BIG_CPU;

		if (sched_enable_power_aware &&
		lower_power_cpu_available(p, cpu_of(rq)))
		return 1;
		return MOVE_TO_POWER_EFFICIENT_CPU;

		return 0;
		}

		/*
		* cpu-bound tasks will not go through select_best_cpu() and hence can be stuck
		* on the wrong cpu. Check if any such tasks need to be "force-migrated"
		* Check if currently running task should be migrated to a better cpu.
		*
		* Todo: Effect this via changes to nohz_balancer_kick() and load balance?
		*/
		@@ -2050,10 +2088,11 @@ void check_for_migration(struct rq rq, struct task_struct p)
		{
		int cpu = cpu_of(rq), new_cpu = cpu;
		unsigned long flags;
		int active_balance = 0;
		int active_balance = 0, rc;

		if (migration_needed(rq, p))
		new_cpu = select_best_cpu(p, cpu);
		rc = migration_needed(rq, p);
		if (rc)
		new_cpu = select_best_cpu(p, cpu, rc);

		if (new_cpu == cpu)
		return;
		@@ -2088,7 +2127,7 @@ static inline int nr_big_tasks(struct rq *rq)

		#define sched_enable_power_aware 0

		static inline int select_best_cpu(struct task_struct *p, int target)
		static inline int select_best_cpu(struct task_struct *p, int target, int reason)
		{
		return 0;
		}
		@@ -4424,7 +4463,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
		return prev_cpu;

		if (sched_enable_hmp)
		return select_best_cpu(p, prev_cpu);
		return select_best_cpu(p, prev_cpu, 0);

		if (sd_flag & SD_BALANCE_WAKE) {
		if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))