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Subject[PATCH v3] sched/fair: use utilization to select misfit task
Date
utilization is used to detect a misfit task but the load is then used to
select the task on the CPU which can lead to select a small task with
high weight instead of the task that triggered the misfit migration.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
Keep tracking load instead of utilization but check that
task doesn't fit CPU's capacity when selecting the task to detach as
suggested by Valentin

kernel/sched/fair.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 53e64a7..8496118 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7487,15 +7487,9 @@ static int detach_tasks(struct lb_env *env)
break;

case migrate_misfit:
- load = task_h_load(p);
-
- /*
- * utilization of misfit task might decrease a bit
- * since it has been recorded. Be conservative in the
- * condition.
- */
- if (load < env->imbalance)
- goto next;
+ /* This is not a misfit task */
+ if (task_fits_capacity(p, capacity_of(env->src_cpu)))
+ goto next;

env->imbalance = 0;
break;
--
2.7.4
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