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Commit c607575e authored by Joonwoo Park's avatar Joonwoo Park
Browse files

sched/rt: take cumulative window demand into consideration 



When all other conditions are same, by placing task on the least
cumulative window demand CPU, we can restrain CPU frequency and
reduce energy cost.

Select the least cumulative window demand CPU when in such case.

Change-Id: Id9ea531d67cfd6d560c8b99dd52e882f912b96a9
Signed-off-by: default avatarJoonwoo Park <joonwoop@codeaurora.org>
parent 188a83c4

kernel/sched/rt.c

+16 −6
Original line number Diff line number Diff line
@@ -1724,6 +1724,8 @@ static int find_lowest_rq(struct task_struct *task) 
	unsigned long cpu_capacity;

	unsigned long best_capacity;

	unsigned long util, best_cpu_util = ULONG_MAX;

	unsigned long best_cpu_util_cum = ULONG_MAX;

	unsigned long util_cum;

	unsigned long tutil = task_util(task);

	int best_cpu_idle_idx = INT_MAX;

	int cpu_idle_idx = -1;
@@ -1813,17 +1815,25 @@ static int find_lowest_rq(struct task_struct *task) 
			/*

			 * If candidate CPU is the previous CPU, select it.

			 * Otherwise, if its load is same with best_cpu and in

			 * a shallower C-state, select it.

			 * a shallower C-state, select it.  If all above

			 * conditions are same, select the least cumulative

			 * window demand CPU.

			 */

			if (sysctl_sched_cstate_aware)

				cpu_idle_idx = idle_get_state_idx(cpu_rq(cpu));

			if (cpu != task_cpu(task) &&

			    sysctl_sched_cstate_aware) {

				if (best_cpu_util == util &&

				    best_cpu_idle_idx < cpu_idle_idx)



			util_cum = cpu_util_cum(cpu, 0);

			if (cpu != task_cpu(task) && best_cpu_util == util) {

				if (best_cpu_idle_idx < cpu_idle_idx)

					continue;



				if (best_cpu_idle_idx == cpu_idle_idx &&

				    best_cpu_util_cum < util_cum)

					continue;

			}



			best_cpu_idle_idx = cpu_idle_idx;

			best_cpu_util_cum = util_cum;

			best_cpu_util = util;

			best_cpu = cpu;

		}