On Tue, Aug 26, 2014 at 01:06:54PM +0200, Vincent Guittot wrote:
> The scheduler tries to compute how many tasks a group of CPUs can handle by
> assuming that a task's load is SCHED_LOAD_SCALE and a CPU capacity is
> SCHED_CAPACITY_SCALE.
> We can now have a better idea of the capacity of a group of CPUs and of the
> utilization of this group thanks to the rework of group_capacity_orig and the
> group_utilization. We can now deduct how many capacity is still available.
>
> Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
> ---
A few minor changes I did while going through it.
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5669,7 +5669,7 @@ struct sg_lb_stats {
unsigned int idle_cpus;
unsigned int group_weight;
enum group_type group_type;
- int group_out_of_capacity;
+ int group_no_capacity;
#ifdef CONFIG_NUMA_BALANCING
unsigned int nr_numa_running;
unsigned int nr_preferred_running;
@@ -5931,37 +5931,37 @@ static inline int sg_imbalanced(struct s
return group->sgc->imbalance;
}
-static inline int group_has_free_capacity(struct sg_lb_stats *sgs,
- struct lb_env *env)
+static inline bool
+group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs)
{
if ((sgs->group_capacity_orig * 100) >
(sgs->group_utilization * env->sd->imbalance_pct))
- return 1;
+ return true;
if (sgs->sum_nr_running < sgs->group_weight)
- return 1;
+ return true;
- return 0;
+ return false;
}
-static inline int group_is_overloaded(struct sg_lb_stats *sgs,
- struct lb_env *env)
+static inline bool
+group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs)
{
if (sgs->sum_nr_running <= sgs->group_weight)
- return 0;
+ return false;
if ((sgs->group_capacity_orig * 100) <
(sgs->group_utilization * env->sd->imbalance_pct))
- return 1;
+ return true;
- return 0;
+ return false;
}
-static enum group_type
-group_classify(struct sched_group *group, struct sg_lb_stats *sgs,
- struct lb_env *env)
+static enum group_type group_classify(struct lb_env *env,
+ struct sched_group *group,
+ struct sg_lb_stats *sgs)
{
- if (group_is_overloaded(sgs, env))
+ if (group_is_overloaded(env, sgs))
return group_overloaded;
if (sg_imbalanced(group))
@@ -6024,9 +6024,8 @@ static inline void update_sg_lb_stats(st
sgs->group_weight = group->group_weight;
- sgs->group_type = group_classify(group, sgs, env);
-
- sgs->group_out_of_capacity = group_is_overloaded(sgs, env);
+ sgs->group_type = group_classify(env, group, sgs);
+ sgs->group_no_capacity = group_is_overloaded(env, sgs);
}
/**
@@ -6157,9 +6156,9 @@ static inline void update_sd_lb_stats(st
* with a large weight task outweighs the tasks on the system).
*/
if (prefer_sibling && sds->local &&
- group_has_free_capacity(&sds->local_stat, env)) {
+ group_has_capacity(env, &sds->local_stat)) {
if (sgs->sum_nr_running > 1)
- sgs->group_out_of_capacity = 1;
+ sgs->group_no_capacity = 1;
sgs->group_capacity = min(sgs->group_capacity,
SCHED_CAPACITY_SCALE);
}
@@ -6430,9 +6429,8 @@ static struct sched_group *find_busiest_
goto force_balance;
/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
- if (env->idle == CPU_NEWLY_IDLE &&
- group_has_free_capacity(local, env) &&
- busiest->group_out_of_capacity)
+ if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) &&
+ busiest->group_no_capacity)
goto force_balance;
/*
--
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