When we pick the next task, we will do the following for the task:
1) p->se.exec_start = rq_clock_task(rq);
2) dequeue_pushable{_dl}_task(rq, p);
When we call set_curr_task_{rt,dl}(), we also need to do the same thing
above. In rt.c, the code at 1) is in the _pick_next_task_rt() and the
code at 2) is in the pick_next_task_rt(). If we put two operations in
one function, maybe better. So, we introduce a new function
set_next_task(), which is responsible for doing the above.
By introducing the function we can get rid of calling the
dequeue_pushable{_dl}_task() directly(We can call set_next_task()) in
pick_next_task_{rt,dl}() and have better code readability and reuse.
In set_curr_task_{rt,dl}(), we also can call set_next_task().
Do this things such that we end up with:
static struct task_struct *pick_next_task_{rt,dl}(struct rq *rq,
struct task_struct *prev, struct rq_flags *rf)
{
/* do something else ... */
put_prev_task(rq, prev);
/* pick next task p */
set_next_task(rq, p);
/* do something else ... */
}
put_prev_task() can match set_next_task(), which can make the
code more readable.
Signed-off-by: Muchun Song <[email protected]>
---
kernel/sched/deadline.c | 19 ++++++++++---------
kernel/sched/rt.c | 26 ++++++++++++--------------
2 files changed, 22 insertions(+), 23 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 91e4202b0634..470ba6b464fe 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1695,6 +1695,14 @@ 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)
+{
+ p->se.exec_start = rq_clock_task(rq);
+
+ /* You can't push away the running task */
+ dequeue_pushable_dl_task(rq, p);
+}
+
static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
struct dl_rq *dl_rq)
{
@@ -1750,10 +1758,8 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
BUG_ON(!dl_se);
p = dl_task_of(dl_se);
- p->se.exec_start = rq_clock_task(rq);
- /* Running task will never be pushed. */
- dequeue_pushable_dl_task(rq, p);
+ set_next_task(rq, p);
if (hrtick_enabled(rq))
start_hrtick_dl(rq, p);
@@ -1808,12 +1814,7 @@ static void task_fork_dl(struct task_struct *p)
static void set_curr_task_dl(struct rq *rq)
{
- struct task_struct *p = rq->curr;
-
- p->se.exec_start = rq_clock_task(rq);
-
- /* You can't push away the running task */
- dequeue_pushable_dl_task(rq, p);
+ set_next_task(rq, rq->curr);
}
#ifdef CONFIG_SMP
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a21ea6021929..481bb7aa25c5 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1498,6 +1498,14 @@ 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)
+{
+ p->se.exec_start = rq_clock_task(rq);
+
+ /* The running task is never eligible for pushing */
+ dequeue_pushable_task(rq, p);
+}
+
static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
struct rt_rq *rt_rq)
{
@@ -1518,8 +1526,7 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
static struct task_struct *_pick_next_task_rt(struct rq *rq)
{
struct sched_rt_entity *rt_se;
- struct task_struct *p;
- struct rt_rq *rt_rq = &rq->rt;
+ struct rt_rq *rt_rq = &rq->rt;
do {
rt_se = pick_next_rt_entity(rq, rt_rq);
@@ -1527,10 +1534,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
rt_rq = group_rt_rq(rt_se);
} while (rt_rq);
- p = rt_task_of(rt_se);
- p->se.exec_start = rq_clock_task(rq);
-
- return p;
+ return rt_task_of(rt_se);
}
static struct task_struct *
@@ -1573,8 +1577,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
p = _pick_next_task_rt(rq);
- /* The running task is never eligible for pushing */
- dequeue_pushable_task(rq, p);
+ set_next_task(rq, p);
rt_queue_push_tasks(rq);
@@ -2355,12 +2358,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
static void set_curr_task_rt(struct rq *rq)
{
- struct task_struct *p = rq->curr;
-
- p->se.exec_start = rq_clock_task(rq);
-
- /* The running task is never eligible for pushing */
- dequeue_pushable_task(rq, p);
+ set_next_task(rq, rq->curr);
}
static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
--
2.17.1
What if anything is the difference with v1 (which I found yesterday and
have pending testing).
Hi, Peter
Thanks for your review.
Just update commit message. So there is no difference between them on the code.
Yours,
Muchun Song
Peter Zijlstra <[email protected]> 于2018年11月2日周五 上午12:52写道：
>
>
>
> What if anything is the difference with v1 (which I found yesterday and
> have pending testing).