[PATCH 4/9] sched: Clean up idle task SMP logic

Peter Zijlstra
2014-01-21T11:29:52Z

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The idle post_schedule hook is just a vile waste of time, fix it proper.

Cc: alex.shi@linaro.org
Cc: mingo@kernel.org
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140117140939.GH11314@laptop.programming.kicks-ass.net
---
kernel/sched/fair.c | 5 +++--
kernel/sched/idle_task.c | 21 ++++++---------------
2 files changed, 9 insertions(+), 17 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2416,7 +2416,8 @@ void idle_exit_fair(struct rq *this_rq)
update_rq_runnable_avg(this_rq, 0);
}

-#else
+#else /* CONFIG_SMP */
+
static inline void update_entity_load_avg(struct sched_entity *se,
int update_cfs_rq) {}
static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
@@ -2428,7 +2429,7 @@ static inline void dequeue_entity_load_a
int sleep) {}
static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
int force_update) {}
-#endif
+#endif /* CONFIG_SMP */

static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -13,18 +13,8 @@ select_task_rq_idle(struct task_struct *
{
return task_cpu(p); /* IDLE tasks as never migrated */
}
-
-static void pre_schedule_idle(struct rq *rq, struct task_struct *prev)
-{
- idle_exit_fair(rq);
- rq_last_tick_reset(rq);
-}
-
-static void post_schedule_idle(struct rq *rq)
-{
- idle_enter_fair(rq);
-}
#endif /* CONFIG_SMP */
+
/*
* Idle tasks are unconditionally rescheduled:
*/
@@ -37,8 +27,7 @@ static struct task_struct *pick_next_tas
{
schedstat_inc(rq, sched_goidle);
#ifdef CONFIG_SMP
- /* Trigger the post schedule to do an idle_enter for CFS */
- rq->post_schedule = 1;
+ idle_enter_fair(rq);
#endif
return rq->idle;
}
@@ -58,6 +47,10 @@ dequeue_task_idle(struct rq *rq, struct

static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
+#ifdef CONFIG_SMP
+ idle_exit_fair(rq);
+ rq_last_tick_reset(rq);
+#endif
}

static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
@@ -101,8 +94,6 @@ const struct sched_class idle_sched_clas

#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_idle,
- .pre_schedule = pre_schedule_idle,
- .post_schedule = post_schedule_idle,
#endif

.set_curr_task = set_curr_task_idle,