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.guittot@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;
/*