[tip:sched/core] sched/{rt,deadline}: Fix set_next_task vs pick_next_task

From: tip-bot for Peter Zijlstra
Date: Thu Aug 08 2019 - 06:56:21 EST


Commit-ID: f95d4eaee6d0207bff2dc93371133d31227d4cfb
Gitweb: https://git.kernel.org/tip/f95d4eaee6d0207bff2dc93371133d31227d4cfb
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 29 May 2019 20:36:40 +0000
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitDate: Thu, 8 Aug 2019 09:09:30 +0200

sched/{rt,deadline}: Fix set_next_task vs pick_next_task

Because pick_next_task() implies set_curr_task() and some of the
details haven't mattered too much, some of what _should_ be in
set_curr_task() ended up in pick_next_task, correct this.

This prepares the way for a pick_next_task() variant that does not
affect the current state; allowing remote picking.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Aaron Lu <aaron.lwe@xxxxxxxxx>
Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: mingo@xxxxxxxxxx
Cc: Phil Auld <pauld@xxxxxxxxxx>
Cc: Julien Desfossez <jdesfossez@xxxxxxxxxxxxxxxx>
Cc: Nishanth Aravamudan <naravamudan@xxxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/38c61d5240553e043c27c5e00b9dd0d184dd6081.1559129225.git.vpillai@xxxxxxxxxxxxxxxx
---
kernel/sched/deadline.c | 22 +++++++++++-----------
kernel/sched/rt.c | 26 +++++++++++++-------------
2 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 039dde2b1dac..2dc2784b196c 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1727,12 +1727,20 @@ static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
}
#endif

-static inline void set_next_task(struct rq *rq, struct task_struct *p)
+static void set_next_task_dl(struct rq *rq, struct task_struct *p)
{
p->se.exec_start = rq_clock_task(rq);

/* You can't push away the running task */
dequeue_pushable_dl_task(rq, p);
+
+ if (hrtick_enabled(rq))
+ start_hrtick_dl(rq, p);
+
+ if (rq->curr->sched_class != &dl_sched_class)
+ update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+
+ deadline_queue_push_tasks(rq);
}

static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
@@ -1791,15 +1799,7 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)

p = dl_task_of(dl_se);

- set_next_task(rq, p);
-
- if (hrtick_enabled(rq))
- start_hrtick_dl(rq, p);
-
- deadline_queue_push_tasks(rq);
-
- if (rq->curr->sched_class != &dl_sched_class)
- update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+ set_next_task_dl(rq, p);

return p;
}
@@ -1846,7 +1846,7 @@ static void task_fork_dl(struct task_struct *p)

static void set_curr_task_dl(struct rq *rq)
{
- set_next_task(rq, rq->curr);
+ set_next_task_dl(rq, rq->curr);
}

#ifdef CONFIG_SMP
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a532558a5176..40bb71004325 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1498,12 +1498,22 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag
#endif
}

-static inline void set_next_task(struct rq *rq, struct task_struct *p)
+static inline void set_next_task_rt(struct rq *rq, struct task_struct *p)
{
p->se.exec_start = rq_clock_task(rq);

/* The running task is never eligible for pushing */
dequeue_pushable_task(rq, p);
+
+ /*
+ * If prev task was rt, put_prev_task() has already updated the
+ * utilization. We only care of the case where we start to schedule a
+ * rt task
+ */
+ if (rq->curr->sched_class != &rt_sched_class)
+ update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+
+ rt_queue_push_tasks(rq);
}

static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
@@ -1577,17 +1587,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)

p = _pick_next_task_rt(rq);

- set_next_task(rq, p);
-
- rt_queue_push_tasks(rq);
-
- /*
- * If prev task was rt, put_prev_task() has already updated the
- * utilization. We only care of the case where we start to schedule a
- * rt task
- */
- if (rq->curr->sched_class != &rt_sched_class)
- update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+ set_next_task_rt(rq, p);

return p;
}
@@ -2356,7 +2356,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)

static void set_curr_task_rt(struct rq *rq)
{
- set_next_task(rq, rq->curr);
+ set_next_task_rt(rq, rq->curr);
}

static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)