On 23/09/14 17:08, Vincent Guittot wrote:

[...]

Finally, the sched_group->sched_group_capacity->capacity_orig has been removed
because it's more used during load balance.

So you're not forced to call it rq->cpu_capacity_orig any more, you
could use rq->cpu_capacity_max instead.

[...]

This review (by PeterZ) during v5 of your patch-set recommended some
renaming (e.g. s/group_has_free_capacity/group_has_capacity and
s/group_out_of_capacity/group_no_capacity as well as reordering of the
parameters which I agree with:

https://lkml.org/lkml/2014/9/11/706

-/*
- * Compute the group capacity factor.
- *
- * Avoid the issue where N*frac(smt_capacity) >= 1 creates 'phantom' cores by
- * first dividing out the smt factor and computing the actual number of cores
- * and limit unit capacity with that.
- */
-static inline int sg_capacity_factor(struct lb_env *env, struct sched_group *group)
+static inline int group_has_free_capacity(struct sg_lb_stats *sgs,

s/static inline int/static inline bool

+                       struct lb_env *env)
 {
-       unsigned int capacity_factor, smt, cpus;
-       unsigned int capacity, capacity_orig;
+       if ((sgs->group_capacity * 100) >
+                       (sgs->group_usage * env->sd->imbalance_pct))
+               return true;

-       capacity = group->sgc->capacity;
-       capacity_orig = group->sgc->capacity_orig;
-       cpus = group->group_weight;
+       if (sgs->sum_nr_running < sgs->group_weight)
+               return true;

-       /* smt := ceil(cpus / capacity), assumes: 1 < smt_capacity < 2 */
-       smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, capacity_orig);
-       capacity_factor = cpus / smt; /* cores */
+       return false;
+}

-       capacity_factor = min_t(unsigned,
-               capacity_factor, DIV_ROUND_CLOSEST(capacity, SCHED_CAPACITY_SCALE));
-       if (!capacity_factor)
-               capacity_factor = fix_small_capacity(env->sd, group);
+static inline int group_is_overloaded(struct sg_lb_stats *sgs,

s/static inline int/static inline bool

In case sgs->group_type is group_overloaded you could set
sgs->group_out_of_capacity to 1 without calling group_is_overloaded again.

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7cdf271e8e52..52d441c92a4f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c

@@ -6037,7 +6037,8 @@ static inline void update_sg_lb_stats(struct

lb_env *env,

        sgs->group_type = group_classify(group, sgs, env);

-       sgs->group_out_of_capacity = group_is_overloaded(sgs, env);
+       if (sgs->group_type == group_overloaded)
+               sgs->group_out_of_capacity = 1;
 }

[...]