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sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations
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SCHED_LOAD_SCALE is used to increase nice resolution and to
scale cpu_power calculations in the scheduler. This patch
introduces SCHED_POWER_SCALE and converts all uses of
SCHED_LOAD_SCALE for scaling cpu_power to use SCHED_POWER_SCALE
instead.

This is a preparatory patch for increasing the resolution of
SCHED_LOAD_SCALE, and there is no need to increase resolution
for cpu_power calculations.

Signed-off-by: Nikhil Rao <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Nikunj A. Dadhania <[email protected]>
Cc: Srivatsa Vaddagiri <[email protected]>
Cc: Stephan Barwolf <[email protected]>
Cc: Mike Galbraith <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Nikhil Rao authored and Ingo Molnar committed May 20, 2011
1 parent f05998d commit 1399fa7
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Showing 3 changed files with 37 additions and 32 deletions.
13 changes: 8 additions & 5 deletions include/linux/sched.h
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Original file line number Diff line number Diff line change
Expand Up @@ -787,18 +787,21 @@ enum cpu_idle_type {
CPU_MAX_IDLE_TYPES
};

/*
* sched-domains (multiprocessor balancing) declarations:
*/

/*
* Increase resolution of nice-level calculations:
*/
#define SCHED_LOAD_SHIFT 10
#define SCHED_LOAD_SCALE (1L << SCHED_LOAD_SHIFT)

#define SCHED_LOAD_SCALE_FUZZ SCHED_LOAD_SCALE
/*
* Increase resolution of cpu_power calculations
*/
#define SCHED_POWER_SHIFT 10
#define SCHED_POWER_SCALE (1L << SCHED_POWER_SHIFT)

/*
* sched-domains (multiprocessor balancing) declarations:
*/
#ifdef CONFIG_SMP
#define SD_LOAD_BALANCE 0x0001 /* Do load balancing on this domain. */
#define SD_BALANCE_NEWIDLE 0x0002 /* Balance when about to become idle */
Expand Down
4 changes: 2 additions & 2 deletions kernel/sched.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6530,7 +6530,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));

printk(KERN_CONT " %s", str);
if (group->cpu_power != SCHED_LOAD_SCALE) {
if (group->cpu_power != SCHED_POWER_SCALE) {
printk(KERN_CONT " (cpu_power = %d)",
group->cpu_power);
}
Expand Down Expand Up @@ -7905,7 +7905,7 @@ void __init sched_init(void)
#ifdef CONFIG_SMP
rq->sd = NULL;
rq->rd = NULL;
rq->cpu_power = SCHED_LOAD_SCALE;
rq->cpu_power = SCHED_POWER_SCALE;
rq->post_schedule = 0;
rq->active_balance = 0;
rq->next_balance = jiffies;
Expand Down
52 changes: 27 additions & 25 deletions kernel/sched_fair.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1584,7 +1584,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
}

/* Adjust by relative CPU power of the group */
avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
avg_load = (avg_load * SCHED_POWER_SCALE) / group->cpu_power;

if (local_group) {
this_load = avg_load;
Expand Down Expand Up @@ -1722,7 +1722,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
nr_running += cpu_rq(i)->cfs.nr_running;
}

capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);

if (tmp->flags & SD_POWERSAVINGS_BALANCE)
nr_running /= 2;
Expand Down Expand Up @@ -2570,7 +2570,7 @@ static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,

unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
{
return SCHED_LOAD_SCALE;
return SCHED_POWER_SCALE;
}

unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
Expand Down Expand Up @@ -2607,18 +2607,18 @@ unsigned long scale_rt_power(int cpu)
available = total - rq->rt_avg;
}

if (unlikely((s64)total < SCHED_LOAD_SCALE))
total = SCHED_LOAD_SCALE;
if (unlikely((s64)total < SCHED_POWER_SCALE))
total = SCHED_POWER_SCALE;

total >>= SCHED_LOAD_SHIFT;
total >>= SCHED_POWER_SHIFT;

return div_u64(available, total);
}

static void update_cpu_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = sd->span_weight;
unsigned long power = SCHED_LOAD_SCALE;
unsigned long power = SCHED_POWER_SCALE;
struct sched_group *sdg = sd->groups;

if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
Expand All @@ -2627,7 +2627,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
else
power *= default_scale_smt_power(sd, cpu);

power >>= SCHED_LOAD_SHIFT;
power >>= SCHED_POWER_SHIFT;
}

sdg->cpu_power_orig = power;
Expand All @@ -2637,10 +2637,10 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
else
power *= default_scale_freq_power(sd, cpu);

power >>= SCHED_LOAD_SHIFT;
power >>= SCHED_POWER_SHIFT;

power *= scale_rt_power(cpu);
power >>= SCHED_LOAD_SHIFT;
power >>= SCHED_POWER_SHIFT;

if (!power)
power = 1;
Expand Down Expand Up @@ -2682,7 +2682,7 @@ static inline int
fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
{
/*
* Only siblings can have significantly less than SCHED_LOAD_SCALE
* Only siblings can have significantly less than SCHED_POWER_SCALE
*/
if (!(sd->flags & SD_SHARE_CPUPOWER))
return 0;
Expand Down Expand Up @@ -2770,7 +2770,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
}

/* Adjust by relative CPU power of the group */
sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->cpu_power;

/*
* Consider the group unbalanced when the imbalance is larger
Expand All @@ -2787,7 +2787,8 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
sgs->group_imb = 1;

sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power,
SCHED_POWER_SCALE);
if (!sgs->group_capacity)
sgs->group_capacity = fix_small_capacity(sd, group);
sgs->group_weight = group->group_weight;
Expand Down Expand Up @@ -2961,7 +2962,7 @@ static int check_asym_packing(struct sched_domain *sd,
return 0;

*imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->cpu_power,
SCHED_LOAD_SCALE);
SCHED_POWER_SCALE);
return 1;
}

Expand Down Expand Up @@ -2990,7 +2991,7 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds,
cpu_avg_load_per_task(this_cpu);

scaled_busy_load_per_task = sds->busiest_load_per_task
* SCHED_LOAD_SCALE;
* SCHED_POWER_SCALE;
scaled_busy_load_per_task /= sds->busiest->cpu_power;

if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
Expand All @@ -3009,26 +3010,26 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds,
min(sds->busiest_load_per_task, sds->max_load);
pwr_now += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load);
pwr_now /= SCHED_LOAD_SCALE;
pwr_now /= SCHED_POWER_SCALE;

/* Amount of load we'd subtract */
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
sds->busiest->cpu_power;
if (sds->max_load > tmp)
pwr_move += sds->busiest->cpu_power *
min(sds->busiest_load_per_task, sds->max_load - tmp);

/* Amount of load we'd add */
if (sds->max_load * sds->busiest->cpu_power <
sds->busiest_load_per_task * SCHED_LOAD_SCALE)
sds->busiest_load_per_task * SCHED_POWER_SCALE)
tmp = (sds->max_load * sds->busiest->cpu_power) /
sds->this->cpu_power;
else
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
sds->this->cpu_power;
pwr_move += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load + tmp);
pwr_move /= SCHED_LOAD_SCALE;
pwr_move /= SCHED_POWER_SCALE;

/* Move if we gain throughput */
if (pwr_move > pwr_now)
Expand Down Expand Up @@ -3070,7 +3071,7 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
load_above_capacity = (sds->busiest_nr_running -
sds->busiest_group_capacity);

load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_LOAD_SCALE);
load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);

load_above_capacity /= sds->busiest->cpu_power;
}
Expand All @@ -3090,7 +3091,7 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
/* How much load to actually move to equalise the imbalance */
*imbalance = min(max_pull * sds->busiest->cpu_power,
(sds->avg_load - sds->this_load) * sds->this->cpu_power)
/ SCHED_LOAD_SCALE;
/ SCHED_POWER_SCALE;

/*
* if *imbalance is less than the average load per runnable task
Expand Down Expand Up @@ -3159,7 +3160,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
if (!sds.busiest || sds.busiest_nr_running == 0)
goto out_balanced;

sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;

/*
* If the busiest group is imbalanced the below checks don't
Expand Down Expand Up @@ -3238,7 +3239,8 @@ find_busiest_queue(struct sched_domain *sd, struct sched_group *group,

for_each_cpu(i, sched_group_cpus(group)) {
unsigned long power = power_of(i);
unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
unsigned long capacity = DIV_ROUND_CLOSEST(power,
SCHED_POWER_SCALE);
unsigned long wl;

if (!capacity)
Expand All @@ -3263,7 +3265,7 @@ find_busiest_queue(struct sched_domain *sd, struct sched_group *group,
* the load can be moved away from the cpu that is potentially
* running at a lower capacity.
*/
wl = (wl * SCHED_LOAD_SCALE) / power;
wl = (wl * SCHED_POWER_SCALE) / power;

if (wl > max_load) {
max_load = wl;
Expand Down

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