[PATCH 2/6] sched/fair: Defer calculation of prev_eff_load in wake_affine until needed

[Mel Gorman]

On sync wakeups, the previous CPU effective load may not be used so delay
the calculation until it's needed.

Signed-off-by: Mel Gorman <mgor...@techsingularity.net>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4b3e86eb2222..c1091cb023c4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5724,7 +5724,6 @@ wake_affine_weight(struct sched_domain *sd, struct 
task_struct *p,
        unsigned long task_load;
 
        this_eff_load = target_load(this_cpu, sd->wake_idx);
-       prev_eff_load = source_load(prev_cpu, sd->wake_idx);
 
        if (sync) {
                unsigned long current_load = task_h_load(current);
@@ -5742,6 +5741,7 @@ wake_affine_weight(struct sched_domain *sd, struct 
task_struct *p,
                this_eff_load *= 100;
        this_eff_load *= capacity_of(prev_cpu);
 
+       prev_eff_load = source_load(prev_cpu, sd->wake_idx);
        prev_eff_load -= task_load;
        if (sched_feat(WA_BIAS))
                prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
-- 
2.15.1