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Commit 7cc02920 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti
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sched/fair: Add bias towards previous CPU for high wakeup rate tasks 



Skip the CPU selection algorithm for high wakeup rate tasks and select
the previous CPU if it is idle.

Change-Id: I99493c8c37e091c79723ee22a5230fbb6f4e33b9
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent 77ecebbc

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1768,6 +1768,7 @@ struct task_struct { 
	struct sched_entity se;

	struct sched_rt_entity rt;

	u64 last_sleep_ts;

	u64 last_cpu_selected_ts;

#ifdef CONFIG_SCHED_WALT

	struct ravg ravg;

	/*

kernel/sched/core.c

+1 −0
Original line number Diff line number Diff line
@@ -2330,6 +2330,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p) 
	p->se.nr_migrations		= 0;

	p->se.vruntime			= 0;

	p->last_sleep_ts		= 0;

	p->last_cpu_selected_ts		= 0;



	INIT_LIST_HEAD(&p->se.group_node);

kernel/sched/fair.c

+36 −0
Original line number Diff line number Diff line
@@ -7296,6 +7296,39 @@ bias_to_waker_cpu(struct task_struct *p, int cpu, struct cpumask *rtg_target) 
	       task_fits_max(p, cpu);

}



#define SCHED_SELECT_PREV_CPU_NSEC	2000000

#define SCHED_FORCE_CPU_SELECTION_NSEC	20000000



static inline bool

bias_to_prev_cpu(struct task_struct *p, struct cpumask *rtg_target)

{

	int prev_cpu = task_cpu(p);

#ifdef CONFIG_SCHED_WALT

	u64 ms = p->ravg.mark_start;

#else

	u64 ms = sched_clock();

#endif



	if (cpu_isolated(prev_cpu) || !idle_cpu(prev_cpu))

		return false;



	if (!ms)

		return false;



	if (ms - p->last_cpu_selected_ts >= SCHED_SELECT_PREV_CPU_NSEC) {

		p->last_cpu_selected_ts = ms;

		return false;

	}



	if (ms - p->last_sleep_ts >= SCHED_SELECT_PREV_CPU_NSEC)

		return false;



	if (rtg_target && !cpumask_test_cpu(prev_cpu, rtg_target))

		return false;



	return true;

}



#ifdef CONFIG_SCHED_WALT

static inline struct cpumask *find_rtg_target(struct task_struct *p)

{
@@ -7374,6 +7407,9 @@ static int select_energy_cpu_brute(struct task_struct *p, int prev_cpu, int sync 
		}

	}



	if (bias_to_prev_cpu(p, rtg_target))

		return prev_cpu;



	rcu_read_lock();



	sd = rcu_dereference(per_cpu(sd_ea, prev_cpu));