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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: Mel Gorman <mgorman@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mel Gorman 2014-08-06 14:19:21 +01:00 committed by Rafael J. Wysocki
parent 64b4ca5cb6
commit 372ba8cb46
4 changed files with 15 additions and 19 deletions
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17
drivers/cpuidle/governors/menu.c
View File

@ -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;

3
include/linux/sched.h
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@ -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);

7
kernel/sched/core.c
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@ -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
/*

7
kernel/sched/proc.c
View File

@ -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
*