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Commit c0d07e76 authored Oct 11, 2017 by Pavankumar Kondeti

sched/fair: Skip energy_diff() for need_idle tasks



The need_idle eligible tasks are placed on the least loaded
CPUs including idle CPUs. The energy_diff() can overturn this
decision if utilizing this idle CPU results in higher power.
Since need_idle eligible tasks scheduling latency is critical
for performance, skip energy_diff() for such tasks.

Change-Id: Ic72c0ed9461a5f91a2f0de055765fd9b2457cdde
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>

parent 79830a25

include/trace/events/sched.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -786,6 +786,11 @@ DEFINE_EVENT(sched_task_util, sched_task_util_imbalance,
		TP_PROTO(struct task_struct *p, int task_cpu, unsigned long task_util, int nominated_cpu, int target_cpu, int ediff, bool need_idle),
		TP_ARGS(p, task_cpu, task_util, nominated_cpu, target_cpu, ediff, need_idle)
		);

		DEFINE_EVENT(sched_task_util, sched_task_util_need_idle,
		TP_PROTO(struct task_struct *p, int task_cpu, unsigned long task_util, int nominated_cpu, int target_cpu, int ediff, bool need_idle),
		TP_ARGS(p, task_cpu, task_util, nominated_cpu, target_cpu, ediff, need_idle)
		);
		#endif

		/*

kernel/sched/fair.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -7144,6 +7144,14 @@ static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync)
		return target_cpu;
		}

		if (need_idle) {
		trace_sched_task_util_need_idle(p, task_cpu(p),
		task_util(p),
		target_cpu, target_cpu,
		0, need_idle);
		return target_cpu;
		}

		/*
		* We always want to migrate the task to the best CPU when
		* placement boost is active.