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Commit 3c443961 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti
Browse files

sched: add sched_get_cpu_last_busy_time() API 



sched_get_cpu_last_busy_time() returns the last time stamp when
a given CPU is busy with more than 2 runnable tasks or has load
greater than 50% of it's max capacity. The LPM driver can make
use of this API and create a policy to prevent a recently loaded
CPU entering deep sleep state.

This API is implemented only for the higher capacity CPUs in
the system. It returns 0 for other CPUs.

Change-Id: I97ef47970a71647f4f55f21165d0cc1351770a53
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent a337c17c

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -182,6 +182,7 @@ extern void sched_update_nr_prod(int cpu, long delta, bool inc); 
extern void sched_get_nr_running_avg(int *avg, int *iowait_avg, int *big_avg,

				     unsigned int *max_nr,

				     unsigned int *big_max_nr);

extern u64 sched_get_cpu_last_busy_time(int cpu);



extern void calc_global_load(unsigned long ticks);

kernel/sched/sched.h

+5 −0
Original line number Diff line number Diff line
@@ -1272,6 +1272,11 @@ static inline bool is_max_capacity_cpu(int cpu) 
	return cpu_max_possible_capacity(cpu) == max_possible_capacity;

}



static inline bool is_min_capacity_cpu(int cpu)

{

	return cpu_max_possible_capacity(cpu) == min_max_possible_capacity;

}



/*

 * 'load' is in reference to "best cpu" at its best frequency.

 * Scale that in reference to a given cpu, accounting for how bad it is

kernel/sched/sched_avg.c

+45 −1
Original line number Diff line number Diff line 
/* Copyright (c) 2012, 2015-2017, The Linux Foundation. All rights reserved.

/* Copyright (c) 2012, 2015-2017, 2018 The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -119,6 +119,43 @@ void sched_get_nr_running_avg(int *avg, int *iowait_avg, int *big_avg, 
}

EXPORT_SYMBOL(sched_get_nr_running_avg);



static DEFINE_PER_CPU(atomic64_t, last_busy_time) = ATOMIC64_INIT(0);



#define BUSY_NR_RUN		3

#define BUSY_LOAD_FACTOR	10



#ifdef CONFIG_SCHED_HMP

static inline void update_last_busy_time(int cpu, bool dequeue,

				unsigned long prev_nr_run, u64 curr_time)

{

	bool nr_run_trigger = false, load_trigger = false;



	if (!hmp_capable() || is_min_capacity_cpu(cpu))

		return;



	if (prev_nr_run >= BUSY_NR_RUN && per_cpu(nr, cpu) < BUSY_NR_RUN)

		nr_run_trigger = true;



	if (dequeue) {

		u64 load;



		load = cpu_rq(cpu)->hmp_stats.cumulative_runnable_avg;

		load = scale_load_to_cpu(load, cpu);



		if (load * BUSY_LOAD_FACTOR > sched_ravg_window)

			load_trigger = true;

	}



	if (nr_run_trigger || load_trigger)

		atomic64_set(&per_cpu(last_busy_time, cpu), curr_time);

}

#else

static inline void update_last_busy_time(int cpu, bool dequeue,

				unsigned long prev_nr_run, u64 curr_time)

{

}

#endif



/**

 * sched_update_nr_prod

 * @cpu: The core id of the nr running driver.
@@ -147,9 +184,16 @@ void sched_update_nr_prod(int cpu, long delta, bool inc) 
	if (per_cpu(nr, cpu) > per_cpu(nr_max, cpu))

		per_cpu(nr_max, cpu) = per_cpu(nr, cpu);



	update_last_busy_time(cpu, !inc, nr_running, curr_time);



	per_cpu(nr_prod_sum, cpu) += nr_running * diff;

	per_cpu(nr_big_prod_sum, cpu) += nr_eligible_big_tasks(cpu) * diff;

	per_cpu(iowait_prod_sum, cpu) += nr_iowait_cpu(cpu) * diff;

	spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);

}

EXPORT_SYMBOL(sched_update_nr_prod);



u64 sched_get_cpu_last_busy_time(int cpu)

{

	return atomic64_read(&per_cpu(last_busy_time, cpu));

}