[PATCH 06/18] sched,dl: Remove return value from pull_dl_task()

Peter Zijlstra
2015-06-11T12:55:59Z

[-- Attachment #1: peterz-sched-post_schedule-4.patch --]
[-- Type: text/plain, Size: 2135 bytes --]

In order to be able to use pull_dl_task() from a callback, we need to
do away with the return value.

Since the return value indicates if we should reschedule, do this
inside the function. Since not all callers currently do this, this can
increase the number of reschedules due rt balancing.

Too many reschedules is not a correctness issues, too few are.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/deadline.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -298,9 +298,8 @@ static inline bool need_pull_dl_task(str
return false;
}

-static inline int pull_dl_task(struct rq *rq)
+static inline void pull_dl_task(struct rq *rq)
{
- return 0;
}

static inline void queue_push_tasks(struct rq *rq)
@@ -1049,7 +1048,7 @@ static void check_preempt_equal_dl(struc
resched_curr(rq);
}

-static int pull_dl_task(struct rq *this_rq);
+static void pull_dl_task(struct rq *this_rq);

#endif /* CONFIG_SMP */

@@ -1480,15 +1479,16 @@ static void push_dl_tasks(struct rq *rq)
;
}

-static int pull_dl_task(struct rq *this_rq)
+static void pull_dl_task(struct rq *this_rq)
{
- int this_cpu = this_rq->cpu, ret = 0, cpu;
+ int this_cpu = this_rq->cpu, cpu;
struct task_struct *p;
+ bool resched = false;
struct rq *src_rq;
u64 dmin = LONG_MAX;

if (likely(!dl_overloaded(this_rq)))
- return 0;
+ return;

/*
* Match the barrier from dl_set_overloaded; this guarantees that if we
@@ -1543,7 +1543,7 @@ static int pull_dl_task(struct rq *this_
src_rq->curr->dl.deadline))
goto skip;

- ret = 1;
+ resched = true;

deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
@@ -1556,7 +1556,8 @@ static int pull_dl_task(struct rq *this_
double_unlock_balance(this_rq, src_rq);
}

- return ret;
+ if (resched)
+ resched_curr(this_rq);
}

/*
@@ -1712,8 +1713,7 @@ static void switched_from_dl(struct rq *
if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
return;

- if (pull_dl_task(rq))
- resched_curr(rq);
+ pull_dl_task(rq);
}

/*