[RFC][PATCH 11/10] sched, fair: Reduce local_group logic

From: Peter Zijlstra
Date: Wed Aug 28 2013 - 04:56:08 EST



Subject: sched, fair: Reduce local_group logic
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Wed Aug 28 10:32:32 CEST 2013

Try and reduce the local_group logic by pulling most of it into
update_sd_lb_stats.

We could completely get rid of the local_group variable, but that
results in two calls to update_sg_lb_stats() and that blows up the
object size by about 2k :/

Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
kernel/sched/fair.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4561,6 +4561,8 @@ static inline void update_sg_lb_stats(st
unsigned long load;
int i;

+ memset(sgs, 0, sizeof(*sgs));
+
for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
struct rq *rq = cpu_rq(i);

@@ -4579,10 +4581,6 @@ static inline void update_sg_lb_stats(st
sgs->idle_cpus++;
}

- if (local_group && (env->idle != CPU_NEWLY_IDLE ||
- time_after_eq(jiffies, group->sgp->next_update)))
- update_group_power(env->sd, env->dst_cpu);
-
/* Adjust by relative CPU power of the group */
sgs->group_power = group->sgp->power;
sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_power;
@@ -4675,11 +4673,17 @@ static inline void update_sd_lb_stats(st
if (local_group) {
sds->local = sg;
sgs = &sds->local_stat;
+
+ if (env->idle != CPU_NEWLY_IDLE ||
+ time_after_eq(jiffies, sg->sgp->next_update))
+ update_group_power(env->sd, env->dst_cpu);
}

- memset(sgs, 0, sizeof(*sgs));
update_sg_lb_stats(env, sg, load_idx, local_group, sgs);

+ if (local_group)
+ goto next_group;
+
/*
* In case the child domain prefers tasks go to siblings
* first, lower the sg capacity to one so that we'll try
@@ -4690,19 +4694,20 @@ static inline void update_sd_lb_stats(st
* 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->local && sds->local_stat.group_has_capacity)
+ if (prefer_sibling && sds->local &&
+ sds->local_stat.group_has_capacity)
sgs->group_capacity = min(sgs->group_capacity, 1U);

- /* Now, start updating sd_lb_stats */
- sds->total_load += sgs->group_load;
- sds->total_pwr += sgs->group_power;
-
- if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
+ if (update_sd_pick_busiest(env, sds, sg, sgs)) {
sds->busiest = sg;
sds->busiest_stat = *sgs;
}

+next_group:
+ /* Now, start updating sd_lb_stats */
+ sds->total_load += sgs->group_load;
+ sds->total_pwr += sgs->group_power;
+
sg = sg->next;
} while (sg != env->sd->groups);
}
--
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