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Commit 567e2ecb authored by Syed Rameez Mustafa's avatar Syed Rameez Mustafa Committed by Gerrit - the friendly Code Review server
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sched: Distinguish between idle and active high power CPUs for small tasks 



This will further prevent small tasks from waking any CPU from a low
power mode.

Change-Id: I9368fafc952fa43ba77012ef0875bd68d612a766
Signed-off-by: default avatarSyed Rameez Mustafa <rameezmustafa@codeaurora.org>
parent e54faa52

kernel/sched/fair.c

+15 −1
Original line number Diff line number Diff line
@@ -1703,6 +1703,8 @@ static int best_small_task_cpu(struct task_struct *p, int sync) 
	int best_mi_cpu = -1, best_mi_cpu_power = INT_MAX;

	int best_idle_lowpower_cpu = -1,

		best_idle_lowpower_cpu_cstate = INT_MAX;

	int best_idle_highpower_cpu = -1,

		best_idle_highpower_cpu_cstate = INT_MAX;

	int best_busy_lowpower_cpu = -1;

	u64 best_busy_lowpower_cpu_load = ULLONG_MAX;

	int best_busy_highpower_cpu = -1;
@@ -1746,7 +1748,8 @@ static int best_small_task_cpu(struct task_struct *p, int sync) 
	 * 2. Shallowest c-state idle CPU in little cluster.

	 * 3. Least busy CPU in little cluster where adding the task

	 *    won't cross spill.

	 * 4. Least busy CPU outside little cluster.

	 * 4. Least busy non-idle CPU outside little cluster.

	 * 5. Shallowest c-state idle CPU outside little cluster.

	 */

	for_each_cpu(i, &search_cpus) {

		struct rq *rq = cpu_rq(i);
@@ -1772,6 +1775,15 @@ static int best_small_task_cpu(struct task_struct *p, int sync) 
		 */

		load = cpu_load_sync(i, sync);

		if (power_delta_exceeded(cost_list[i], min_cost)) {



			if (idle_cpu(i) && cstate) {

				if (cstate < best_idle_highpower_cpu_cstate) {

					best_idle_highpower_cpu = i;

					best_idle_highpower_cpu_cstate = cstate;

				}

				continue;

			}



			if (load < best_busy_highpower_cpu_load) {

				best_busy_highpower_cpu = i;

				best_busy_highpower_cpu_load = load;
@@ -1815,6 +1827,8 @@ static int best_small_task_cpu(struct task_struct *p, int sync) 
		return best_busy_lowpower_cpu;

	if (best_busy_highpower_cpu != -1)

		return best_busy_highpower_cpu;

	if (best_idle_highpower_cpu != -1)

		return best_idle_highpower_cpu;



	return task_cpu(p);

}