Merge "sched: Avoid pulling big tasks to the little cluster during load balance" (ded4c87a) · Commits · e / devices / android_kernel_sony_msm8994

kernel/sched/fair.c

+24 −4

Original line number	Diff line number	Diff line
		@@ -5774,6 +5774,7 @@ static unsigned long __read_mostly max_load_balance_interval = HZ/10;
		#define LBF_IGNORE_SMALL_TASKS 0x08
		#define LBF_PWR_ACTIVE_BALANCE 0x10
		#define LBF_SCHED_BOOST 0x20
		#define LBF_IGNORE_BIG_TASKS 0x40

		struct lb_env {
		struct sched_domain *sd;
		@@ -5856,6 +5857,7 @@ static
		int can_migrate_task(struct task_struct p, struct lb_env env)
		{
		int tsk_cache_hot = 0;
		int twf;
		/*
		* We do not migrate tasks that are:
		* 1) throttled_lb_pair, or
		@@ -5874,8 +5876,22 @@ int can_migrate_task(struct task_struct p, struct lb_env env)
		if (env->flags & LBF_IGNORE_SMALL_TASKS && is_small_task(p))
		return 0;

		if (!task_will_fit(p, env->dst_cpu) &&
		env->busiest_nr_running <= env->busiest_grp_capacity)
		twf = task_will_fit(p, env->dst_cpu);

		/*
		* Attempt to not pull tasks that don't fit. We may get lucky and find
		* one that actually fits.
		*/
		if (env->flags & LBF_IGNORE_BIG_TASKS && !twf)
		return 0;

		/*
		* Group imbalance can sometimes cause work to be pulled across groups
		* even though the group could have managed the imbalance on its own.
		* Prevent inter-cluster migrations for big tasks when the number of
		* tasks is lower than the capacity of the group.
		*/
		if (!twf && env->busiest_nr_running <= env->busiest_grp_capacity)
		return 0;

		if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
		@@ -5989,6 +6005,9 @@ static int move_tasks(struct lb_env *env)

		if (capacity(env->dst_rq) > capacity(env->src_rq))
		env->flags \|= LBF_IGNORE_SMALL_TASKS;
		else if (capacity(env->dst_rq) < capacity(env->src_rq) &&
		!sched_boost())
		env->flags \|= LBF_IGNORE_BIG_TASKS;

		redo:
		while (!list_empty(tasks)) {
		@@ -6044,9 +6063,10 @@ next:
		list_move_tail(&p->se.group_node, tasks);
		}

		if (env->flags & LBF_IGNORE_SMALL_TASKS && !pulled) {
		if (env->flags & (LBF_IGNORE_SMALL_TASKS \| LBF_IGNORE_BIG_TASKS)
		&& !pulled) {
		tasks = &env->src_rq->cfs_tasks;
		env->flags &= ~LBF_IGNORE_SMALL_TASKS;
		env->flags &= ~(LBF_IGNORE_SMALL_TASKS \| LBF_IGNORE_BIG_TASKS);
		env->loop = orig_loop;
		goto redo;
		}