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Commit 2da014c0 authored by Srivatsa Vaddagiri's avatar Srivatsa Vaddagiri Committed by Todd Kjos
Browse files

sched: Extend active balance to accept 'push_task' argument 



Active balance currently picks one task to migrate from busy cpu to
a chosen cpu (push_cpu). This patch extends active load balance to
recognize a particular task ('push_task') that needs to be migrated to
'push_cpu'. This capability will be leveraged by HMP-aware task
placement in a subsequent patch.

Change-Id: If31320111e6cc7044e617b5c3fd6d8e0c0e16952
Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: default avatarSyed Rameez Mustafa <rameezmustafa@codeaurora.org>
parent 3a353d6c

kernel/sched/core.c

+1 −0
Original line number Diff line number Diff line
@@ -7909,6 +7909,7 @@ void __init sched_init(void) 
		rq->active_balance = 0;

		rq->next_balance = jiffies;

		rq->push_cpu = 0;

		rq->push_task = NULL;

		rq->cpu = i;

		rq->online = 0;

		rq->idle_stamp = 0;

kernel/sched/fair.c

+32 −10
Original line number Diff line number Diff line
@@ -9429,8 +9429,18 @@ static int active_load_balance_cpu_stop(void *data) 
	int busiest_cpu = cpu_of(busiest_rq);

	int target_cpu = busiest_rq->push_cpu;

	struct rq *target_rq = cpu_rq(target_cpu);

	struct sched_domain *sd;

	struct sched_domain *sd = NULL;

	struct task_struct *p = NULL;

	struct task_struct *push_task;

	int push_task_detached = 0;

	struct lb_env env = {

		.sd		= sd,

		.dst_cpu	= target_cpu,

		.dst_rq		= target_rq,

		.src_cpu	= busiest_rq->cpu,

		.src_rq		= busiest_rq,

		.idle		= CPU_IDLE,

	};



	raw_spin_lock_irq(&busiest_rq->lock);
@@ -9450,6 +9460,16 @@ static int active_load_balance_cpu_stop(void *data) 
	 */

	BUG_ON(busiest_rq == target_rq);



	push_task = busiest_rq->push_task;

	if (push_task) {

		if (task_on_rq_queued(push_task) &&

				task_cpu(push_task) == busiest_cpu) {

			detach_task(push_task, &env);

			push_task_detached = 1;

		}

		goto out_unlock;

	}



	/* Search for an sd spanning us and the target CPU. */

	rcu_read_lock();

	for_each_domain(target_cpu, sd) {
@@ -9459,15 +9479,7 @@ static int active_load_balance_cpu_stop(void *data) 
	}



	if (likely(sd)) {

		struct lb_env env = {

			.sd		= sd,

			.dst_cpu	= target_cpu,

			.dst_rq		= target_rq,

			.src_cpu	= busiest_rq->cpu,

			.src_rq		= busiest_rq,

			.idle		= CPU_IDLE,

		};



		env.sd = sd;

		schedstat_inc(sd, alb_count);

		update_rq_clock(busiest_rq);
@@ -9485,8 +9497,18 @@ static int active_load_balance_cpu_stop(void *data) 
	rcu_read_unlock();

out_unlock:

	busiest_rq->active_balance = 0;



	if (push_task)

		busiest_rq->push_task = NULL;



	raw_spin_unlock(&busiest_rq->lock);



	if (push_task) {

		if (push_task_detached)

			attach_one_task(target_rq, push_task);

		put_task_struct(push_task);

	}



	if (p)

		attach_one_task(target_rq, p);

kernel/sched/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -664,6 +664,7 @@ struct rq { 
	/* For active balancing */

	int active_balance;

	int push_cpu;

	struct task_struct *push_task;

	struct cpu_stop_work active_balance_work;

	/* cpu of this runqueue: */

	int cpu;