[PATCH v7 9/9] sched/fair: remove check_preempt_from_others

Vincent Guittot
2022-10-28T09:35:58Z

With the dedicated latency list, we don't have to take care of this special
case anymore as pick_next_entity checks for a runnable latency sensitive
task.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/sched/fair.c | 34 ++--------------------------------
1 file changed, 2 insertions(+), 32 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c28992b7d1a6..9a421b49dbfd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5802,35 +5802,6 @@ static int sched_idle_cpu(int cpu)
}
#endif

-static void set_next_buddy(struct sched_entity *se);
-
-static void check_preempt_from_others(struct cfs_rq *cfs, struct sched_entity *se)
-{
- struct sched_entity *next;
-
- if (se->latency_offset >= 0)
- return;
-
- if (cfs->nr_running <= 1)
- return;
- /*
- * When waking from another class, we don't need to check to preempt at
- * wakeup and don't set next buddy as a candidate for being picked in
- * priority.
- * In case of simultaneous wakeup when current is another class, the
- * latency sensitive tasks lost opportunity to preempt non sensitive
- * tasks which woke up simultaneously.
- */
-
- if (cfs->next)
- next = cfs->next;
- else
- next = __pick_first_entity(cfs);
-
- if (next && wakeup_preempt_entity(next, se) == 1)
- set_next_buddy(se);
-}
-
/*
* The enqueue_task method is called before nr_running is
* increased. Here we update the fair scheduling stats and
@@ -5917,15 +5888,14 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (!task_new)
update_overutilized_status(rq);

- if (rq->curr->sched_class != &fair_sched_class)
- check_preempt_from_others(cfs_rq_of(&p->se), &p->se);
-
enqueue_throttle:
assert_list_leaf_cfs_rq(rq);

hrtick_update(rq);
}

+static void set_next_buddy(struct sched_entity *se);
+
/*
* The dequeue_task method is called before nr_running is
* decreased. We remove the task from the rbtree and
--
2.17.1