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Commit 2abf571b authored by Joonwoo Park's avatar Joonwoo Park
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Revert "sched: use cum_window_demand for rt task placement" 



This reverts commit 50543957.

The idea of RT task packing isn't great due to potential performance
disadvantage.  Revert the commit so we can find the least load CPU
in the lowest possible capacity CPU.

Change-Id: I6495e36549a7ed610f0b69697ddc44c79ca600c8
Signed-off-by: default avatarJoonwoo Park <joonwoop@codeaurora.org>
parent 6ce8ab38

kernel/sched/rt.c

+5 −41
Original line number Diff line number Diff line
@@ -1724,11 +1724,6 @@ 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;

	int best_cpu_idle_idx = INT_MAX;

	int cpu_idle_idx = -1;

	long new_util_cum;

	int max_spare_cap_cpu = -1;

	long max_spare_cap = -LONG_MAX;

	bool placement_boost;



	/* Make sure the mask is initialized first */
@@ -1798,48 +1793,17 @@ static int find_lowest_rq(struct task_struct *task) 
				if (sched_cpu_high_irqload(cpu))

					continue;



				new_util_cum = cpu_util_cum(cpu, 0);



				if (!task_in_cum_window_demand(cpu_rq(cpu),

							       task))

					new_util_cum += task_util(task);



				trace_sched_cpu_util(task, cpu, task_util(task),

						     0, new_util_cum, 0);



				if (sysctl_sched_cstate_aware)

					cpu_idle_idx =

					     idle_get_state_idx(cpu_rq(cpu));



				if (add_capacity_margin(new_util_cum, cpu) <

				    capacity_curr_of(cpu)) {

					if (cpu_idle_idx < best_cpu_idle_idx ||

					    (best_cpu != task_cpu(task) &&

					     (best_cpu_idle_idx ==

					      cpu_idle_idx &&

					      best_cpu_util > util))) {

				if (best_cpu_util > util ||

				    (best_cpu_util == util &&

				     cpu == task_cpu(task))) {

					best_cpu_util = util;

					best_cpu = cpu;

						best_cpu_idle_idx =

						    cpu_idle_idx;

					}

				} else {

					long spare_cap = capacity_of(cpu) -

							 util;



					if (spare_cap > 0 &&

					    max_spare_cap < spare_cap) {

						max_spare_cap_cpu = cpu;

						max_spare_cap = spare_cap;

					}

				}

			}

		}



		if (best_cpu != -1) {

			return best_cpu;

		} else if (max_spare_cap_cpu != -1) {

			return max_spare_cap_cpu;

		} else if (!cpumask_empty(&backup_search_cpu)) {

			cpumask_copy(&search_cpu, &backup_search_cpu);

			cpumask_clear(&backup_search_cpu);