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Commit 372ba8cb authored by Mel Gorman's avatar Mel Gorman Committed by Rafael J. Wysocki
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cpuidle: menu: Lookup CPU runqueues less 



The menu governer makes separate lookups of the CPU runqueue to get
load and number of IO waiters but it can be done with a single lookup.

Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 64b4ca5c

drivers/cpuidle/governors/menu.c

+7 −10
Original line number Diff line number Diff line
@@ -134,12 +134,9 @@ struct menu_device { 
#define LOAD_INT(x) ((x) >> FSHIFT)

#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)



static int get_loadavg(void)

static inline int get_loadavg(unsigned long load)

{

	unsigned long this = this_cpu_load();





	return LOAD_INT(this) * 10 + LOAD_FRAC(this) / 10;

	return LOAD_INT(load) * 10 + LOAD_FRAC(load) / 10;

}



static inline int which_bucket(unsigned int duration, unsigned long nr_iowaiters)
@@ -175,13 +172,13 @@ static inline int which_bucket(unsigned int duration, unsigned long nr_iowaiters 
 * to be, the higher this multiplier, and thus the higher

 * the barrier to go to an expensive C state.

 */

static inline int performance_multiplier(unsigned long nr_iowaiters)

static inline int performance_multiplier(unsigned long nr_iowaiters, unsigned long load)

{

	int mult = 1;



	/* for higher loadavg, we are more reluctant */



	mult += 2 * get_loadavg();

	mult += 2 * get_loadavg(load);



	/* for IO wait tasks (per cpu!) we add 5x each */

	mult += 10 * nr_iowaiters;
@@ -296,7 +293,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) 
	int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);

	int i;

	unsigned int interactivity_req;

	unsigned long nr_iowaiters;

	unsigned long nr_iowaiters, cpu_load;



	if (data->needs_update) {

		menu_update(drv, dev);
@@ -312,7 +309,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) 
	/* determine the expected residency time, round up */

	data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());



	nr_iowaiters = nr_iowait_cpu(smp_processor_id());

	get_iowait_load(&nr_iowaiters, &cpu_load);

	data->bucket = which_bucket(data->next_timer_us, nr_iowaiters);



	/*
@@ -331,7 +328,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) 
	 * duration / latency ratio. Adjust the latency limit if

	 * necessary.

	 */

	interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters);

	interactivity_req = data->predicted_us / performance_multiplier(nr_iowaiters, cpu_load);

	if (latency_req > interactivity_req)

		latency_req = interactivity_req;

include/linux/sched.h

+1 −2
Original line number Diff line number Diff line
@@ -168,8 +168,7 @@ extern int nr_processes(void); 
extern unsigned long nr_running(void);

extern unsigned long nr_iowait(void);

extern unsigned long nr_iowait_cpu(int cpu);

extern unsigned long this_cpu_load(void);



extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load);



extern void calc_global_load(unsigned long ticks);

extern void update_cpu_load_nohz(void);

kernel/sched/core.c

+7 −0
Original line number Diff line number Diff line
@@ -2385,6 +2385,13 @@ unsigned long nr_iowait_cpu(int cpu) 
	return atomic_read(&this->nr_iowait);

}



void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)

{

	struct rq *this = this_rq();

	*nr_waiters = atomic_read(&this->nr_iowait);

	*load = this->cpu_load[0];

}



#ifdef CONFIG_SMP



/*

kernel/sched/proc.c

+0 −7
Original line number Diff line number Diff line
@@ -8,13 +8,6 @@ 


#include "sched.h"



unsigned long this_cpu_load(void)

{

	struct rq *this = this_rq();

	return this->cpu_load[0];

}





/*

 * Global load-average calculations

 *