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sched: Clean-up struct sd_lb_stat 

There is no reason to maintain separate variables for this_group
and busiest_group in sd_lb_stat, except saving some space.
But this structure is always allocated in stack, so this saving
isn't really benificial [peterz: reducing stack space is good; in this
case readability increases enough that I think its still beneficial]

This patch unify these variables, so IMO, readability may be improved.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ Rename this to local -- avoids confusion between this_cpu and the C++ this pointer. ]
Reviewed-by: Paul  Turner <pjt@google.com>
[ Lots of style edits, a few fixes and a rename. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Joonsoo Kim 2013-08-06 17:36:43 +09:00 committed by Ingo Molnar
parent 23f0d2093c
commit 56cf515b4b
1 changed files with 114 additions and 115 deletions
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229
kernel/sched/fair.c
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@ -4231,36 +4231,6 @@ static unsigned long task_h_load(struct task_struct *p)
#endif
/********** Helpers for find_busiest_group ************************/
/*
* sd_lb_stats - Structure to store the statistics of a sched_domain
* during load balancing.
*/
struct sd_lb_stats {
struct sched_group *busiest; /* Busiest group in this sd */
struct sched_group *this; /* Local group in this sd */
unsigned long total_load; /* Total load of all groups in sd */
unsigned long total_pwr; /* Total power of all groups in sd */
unsigned long avg_load; /* Average load across all groups in sd */
/** Statistics of this group */
unsigned long this_load;
unsigned long this_load_per_task;
unsigned long this_nr_running;
unsigned long this_has_capacity;
unsigned int this_idle_cpus;
/* Statistics of the busiest group */
unsigned int busiest_idle_cpus;
unsigned long max_load;
unsigned long busiest_load_per_task;
unsigned long busiest_nr_running;
unsigned long busiest_group_capacity;
unsigned long busiest_has_capacity;
unsigned int busiest_group_weight;
int group_imb; /* Is there imbalance in this sd */
};
/*
* sg_lb_stats - stats of a sched_group required for load_balancing
*/
@ -4269,6 +4239,7 @@ struct sg_lb_stats {
unsigned long group_load; /* Total load over the CPUs of the group */
unsigned long sum_nr_running; /* Nr tasks running in the group */
unsigned long sum_weighted_load; /* Weighted load of group's tasks */
unsigned long load_per_task;
unsigned long group_capacity;
unsigned long idle_cpus;
unsigned long group_weight;
@ -4276,6 +4247,21 @@ struct sg_lb_stats {
int group_has_capacity; /* Is there extra capacity in the group? */
};
/*
* sd_lb_stats - Structure to store the statistics of a sched_domain
* during load balancing.
*/
struct sd_lb_stats {
struct sched_group *busiest; /* Busiest group in this sd */
struct sched_group *local; /* Local group in this sd */
unsigned long total_load; /* Total load of all groups in sd */
unsigned long total_pwr; /* Total power of all groups in sd */
unsigned long avg_load; /* Average load across all groups in sd */
struct sg_lb_stats local_stat; /* Statistics of the local group */
struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */
};
/**
* get_sd_load_idx - Obtain the load index for a given sched domain.
* @sd: The sched_domain whose load_idx is to be obtained.
@ -4490,6 +4476,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
load = target_load(i, load_idx);
} else {
load = source_load(i, load_idx);
if (load > max_cpu_load)
max_cpu_load = load;
if (min_cpu_load > load)
@ -4531,10 +4518,12 @@ static inline void update_sg_lb_stats(struct lb_env *env,
(max_nr_running - min_nr_running) > 1)
sgs->group_imb = 1;
sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
SCHED_POWER_SCALE);
sgs->group_capacity =
DIV_ROUND_CLOSEST(group->sgp->power, SCHED_POWER_SCALE);
if (!sgs->group_capacity)
sgs->group_capacity = fix_small_capacity(env->sd, group);
sgs->group_weight = group->group_weight;
if (sgs->group_capacity > sgs->sum_nr_running)
@ -4556,7 +4545,7 @@ static bool update_sd_pick_busiest(struct lb_env *env,
struct sched_group *sg,
struct sg_lb_stats *sgs)
{
if (sgs->avg_load <= sds->max_load)
if (sgs->avg_load <= sds->busiest_stat.avg_load)
return false;
if (sgs->sum_nr_running > sgs->group_capacity)
@ -4593,7 +4582,7 @@ static inline void update_sd_lb_stats(struct lb_env *env,
{
struct sched_domain *child = env->sd->child;
struct sched_group *sg = env->sd->groups;
struct sg_lb_stats sgs;
struct sg_lb_stats tmp_sgs;
int load_idx, prefer_sibling = 0;
if (child && child->flags & SD_PREFER_SIBLING)
@ -4602,14 +4591,17 @@ static inline void update_sd_lb_stats(struct lb_env *env,
load_idx = get_sd_load_idx(env->sd, env->idle);
do {
struct sg_lb_stats *sgs = &tmp_sgs;
int local_group;
local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
memset(&sgs, 0, sizeof(sgs));
update_sg_lb_stats(env, sg, load_idx, local_group, &sgs);
if (local_group) {
sds->local = sg;
sgs = &sds->local_stat;
}
sds->total_load += sgs.group_load;
sds->total_pwr += sg->sgp->power;
memset(sgs, 0, sizeof(*sgs));
update_sg_lb_stats(env, sg, load_idx, local_group, sgs);
/*
* In case the child domain prefers tasks go to siblings
@ -4621,26 +4613,17 @@ static inline void update_sd_lb_stats(struct lb_env *env,
* heaviest group when it is already under-utilized (possible
* with a large weight task outweighs the tasks on the system).
*/
if (prefer_sibling && !local_group && sds->this_has_capacity)
sgs.group_capacity = min(sgs.group_capacity, 1UL);
if (prefer_sibling && !local_group &&
sds->local && sds->local_stat.group_has_capacity)
sgs->group_capacity = min(sgs->group_capacity, 1UL);
if (local_group) {
sds->this_load = sgs.avg_load;
sds->this = sg;
sds->this_nr_running = sgs.sum_nr_running;
sds->this_load_per_task = sgs.sum_weighted_load;
sds->this_has_capacity = sgs.group_has_capacity;
sds->this_idle_cpus = sgs.idle_cpus;
} else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
sds->max_load = sgs.avg_load;
/* Now, start updating sd_lb_stats */
sds->total_load += sgs->group_load;
sds->total_pwr += sg->sgp->power;
if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
sds->busiest = sg;
sds->busiest_nr_running = sgs.sum_nr_running;
sds->busiest_idle_cpus = sgs.idle_cpus;
sds->busiest_group_capacity = sgs.group_capacity;
sds->busiest_load_per_task = sgs.sum_weighted_load;
sds->busiest_has_capacity = sgs.group_has_capacity;
sds->busiest_group_weight = sgs.group_weight;
sds->group_imb = sgs.group_imb;
sds->busiest_stat = *sgs;
}
sg = sg->next;
@ -4684,8 +4667,8 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
if (env->dst_cpu > busiest_cpu)
return 0;
env->imbalance = DIV_ROUND_CLOSEST(
sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
env->imbalance = DIV_ROUND_CLOSEST(sds->busiest_stat.avg_load *
sds->busiest->sgp->power, SCHED_POWER_SCALE);
return 1;
}
@ -4703,24 +4686,23 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
unsigned long tmp, pwr_now = 0, pwr_move = 0;
unsigned int imbn = 2;
unsigned long scaled_busy_load_per_task;
struct sg_lb_stats *local, *busiest;
if (sds->this_nr_running) {
sds->this_load_per_task /= sds->this_nr_running;
if (sds->busiest_load_per_task >
sds->this_load_per_task)
imbn = 1;
} else {
sds->this_load_per_task =
cpu_avg_load_per_task(env->dst_cpu);
}
local = &sds->local_stat;
busiest = &sds->busiest_stat;
scaled_busy_load_per_task = sds->busiest_load_per_task
* SCHED_POWER_SCALE;
scaled_busy_load_per_task /= sds->busiest->sgp->power;
if (!local->sum_nr_running)
local->load_per_task = cpu_avg_load_per_task(env->dst_cpu);
else if (busiest->load_per_task > local->load_per_task)
imbn = 1;
if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
(scaled_busy_load_per_task * imbn)) {
env->imbalance = sds->busiest_load_per_task;
scaled_busy_load_per_task =
(busiest->load_per_task * SCHED_POWER_SCALE) /
sds->busiest->sgp->power;
if (busiest->avg_load - local->avg_load + scaled_busy_load_per_task >=
(scaled_busy_load_per_task * imbn)) {
env->imbalance = busiest->load_per_task;
return;
}
@ -4731,33 +4713,36 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
*/
pwr_now += sds->busiest->sgp->power *
min(sds->busiest_load_per_task, sds->max_load);
pwr_now += sds->this->sgp->power *
min(sds->this_load_per_task, sds->this_load);
min(busiest->load_per_task, busiest->avg_load);
pwr_now += sds->local->sgp->power *
min(local->load_per_task, local->avg_load);
pwr_now /= SCHED_POWER_SCALE;
/* Amount of load we'd subtract */
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
tmp = (busiest->load_per_task * SCHED_POWER_SCALE) /
sds->busiest->sgp->power;
if (sds->max_load > tmp)
if (busiest->avg_load > tmp) {
pwr_move += sds->busiest->sgp->power *
min(sds->busiest_load_per_task, sds->max_load - tmp);
min(busiest->load_per_task,
busiest->avg_load - tmp);
}
/* Amount of load we'd add */
if (sds->max_load * sds->busiest->sgp->power <
sds->busiest_load_per_task * SCHED_POWER_SCALE)
tmp = (sds->max_load * sds->busiest->sgp->power) /
sds->this->sgp->power;
else
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
sds->this->sgp->power;
pwr_move += sds->this->sgp->power *
min(sds->this_load_per_task, sds->this_load + tmp);
if (busiest->avg_load * sds->busiest->sgp->power <
busiest->load_per_task * SCHED_POWER_SCALE) {
tmp = (busiest->avg_load * sds->busiest->sgp->power) /
sds->local->sgp->power;
} else {
tmp = (busiest->load_per_task * SCHED_POWER_SCALE) /
sds->local->sgp->power;
}
pwr_move += sds->local->sgp->power *
min(local->load_per_task, local->avg_load + tmp);
pwr_move /= SCHED_POWER_SCALE;
/* Move if we gain throughput */
if (pwr_move > pwr_now)
env->imbalance = sds->busiest_load_per_task;
env->imbalance = busiest->load_per_task;
}
/**
@ -4769,11 +4754,22 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
{
unsigned long max_pull, load_above_capacity = ~0UL;
struct sg_lb_stats *local, *busiest;
sds->busiest_load_per_task /= sds->busiest_nr_running;
if (sds->group_imb) {
sds->busiest_load_per_task =
min(sds->busiest_load_per_task, sds->avg_load);
local = &sds->local_stat;
if (local->sum_nr_running) {
local->load_per_task =
local->sum_weighted_load / local->sum_nr_running;
}
busiest = &sds->busiest_stat;
/* busiest must have some tasks */
busiest->load_per_task =
busiest->sum_weighted_load / busiest->sum_nr_running;
if (busiest->group_imb) {
busiest->load_per_task =
min(busiest->load_per_task, sds->avg_load);
}
/*
@ -4781,20 +4777,19 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* max load less than avg load(as we skip the groups at or below
* its cpu_power, while calculating max_load..)
*/
if (sds->max_load < sds->avg_load) {
if (busiest->avg_load < sds->avg_load) {
env->imbalance = 0;
return fix_small_imbalance(env, sds);
}
if (!sds->group_imb) {
if (!busiest->group_imb) {
/*
* Don't want to pull so many tasks that a group would go idle.
*/
load_above_capacity = (sds->busiest_nr_running -
sds->busiest_group_capacity);
load_above_capacity =
(busiest->sum_nr_running - busiest->group_capacity);
load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
load_above_capacity /= sds->busiest->sgp->power;
}
@ -4808,12 +4803,14 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* Be careful of negative numbers as they'll appear as very large values
* with unsigned longs.
*/
max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
max_pull = min(busiest->avg_load - sds->avg_load,
load_above_capacity);
/* How much load to actually move to equalise the imbalance */
env->imbalance = min(max_pull * sds->busiest->sgp->power,
(sds->avg_load - sds->this_load) * sds->this->sgp->power)
/ SCHED_POWER_SCALE;
env->imbalance = min(
max_pull * sds->busiest->sgp->power,
(sds->avg_load - local->avg_load) * sds->local->sgp->power
) / SCHED_POWER_SCALE;
/*
* if *imbalance is less than the average load per runnable task
@ -4821,9 +4818,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* a think about bumping its value to force at least one task to be
* moved
*/
if (env->imbalance < sds->busiest_load_per_task)
if (env->imbalance < busiest->load_per_task)
return fix_small_imbalance(env, sds);
}
/******* find_busiest_group() helpers end here *********************/
@ -4845,9 +4841,9 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* return the least loaded group whose CPUs can be
* put to idle by rebalancing its tasks onto our group.
*/
static struct sched_group *
find_busiest_group(struct lb_env *env)
static struct sched_group *find_busiest_group(struct lb_env *env)
{
struct sg_lb_stats *local, *busiest;
struct sd_lb_stats sds;
memset(&sds, 0, sizeof(sds));
@ -4857,13 +4853,15 @@ find_busiest_group(struct lb_env *env)
* this level.
*/
update_sd_lb_stats(env, &sds);
local = &sds.local_stat;
busiest = &sds.busiest_stat;
if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
check_asym_packing(env, &sds))
return sds.busiest;
/* There is no busy sibling group to pull tasks from */
if (!sds.busiest || sds.busiest_nr_running == 0)
if (!sds.busiest || busiest->sum_nr_running == 0)
goto out_balanced;
sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
@ -4873,26 +4871,26 @@ find_busiest_group(struct lb_env *env)
* work because they assumes all things are equal, which typically
* isn't true due to cpus_allowed constraints and the like.
*/
if (sds.group_imb)
if (busiest->group_imb)
goto force_balance;
/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
!sds.busiest_has_capacity)
if (env->idle == CPU_NEWLY_IDLE && local->group_has_capacity &&
!busiest->group_has_capacity)
goto force_balance;
/*
* If the local group is more busy than the selected busiest group
* don't try and pull any tasks.
*/
if (sds.this_load >= sds.max_load)
if (local->avg_load >= busiest->avg_load)
goto out_balanced;
/*
* Don't pull any tasks if this group is already above the domain
* average load.
*/
if (sds.this_load >= sds.avg_load)
if (local->avg_load >= sds.avg_load)
goto out_balanced;
if (env->idle == CPU_IDLE) {
@ -4902,15 +4900,16 @@ find_busiest_group(struct lb_env *env)
* there is no imbalance between this and busiest group
* wrt to idle cpu's, it is balanced.
*/
if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
sds.busiest_nr_running <= sds.busiest_group_weight)
if ((local->idle_cpus < busiest->idle_cpus) &&
busiest->sum_nr_running <= busiest->group_weight)
goto out_balanced;
} else {
/*
* In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
* imbalance_pct to be conservative.
*/
if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
if (100 * busiest->avg_load <=
env->sd->imbalance_pct * local->avg_load)
goto out_balanced;
}