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Subject[tip: sched/core] sched/core: Reorganize ttwu_do_wakeup() and ttwu_do_activate()
The following commit has been merged into the sched/core branch of tip:

Commit-ID: 160fb0d83f206b3429fc495864a022110f9e4978
Gitweb: https://git.kernel.org/tip/160fb0d83f206b3429fc495864a022110f9e4978
Author: Chengming Zhou <zhouchengming@bytedance.com>
AuthorDate: Fri, 23 Dec 2022 18:32:57 +08:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 07 Jan 2023 10:48:38 +01:00

sched/core: Reorganize ttwu_do_wakeup() and ttwu_do_activate()

ttwu_do_activate() is used for a complete wakeup, in which we will
activate_task() and use ttwu_do_wakeup() to mark the task runnable
and perform wakeup-preemption, also call class->task_woken() callback
and update the rq->idle_stamp.

Since ttwu_runnable() is not a complete wakeup, don't need all those
done in ttwu_do_wakeup(), so we can move those to ttwu_do_activate()
to simplify ttwu_do_wakeup(), making it only mark the task runnable
to be reused in ttwu_runnable() and try_to_wake_up().

This patch should not have any functional changes.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20221223103257.4962-2-zhouchengming@bytedance.com
---
kernel/sched/core.c | 64 +++++++++++++++++++++-----------------------
1 file changed, 31 insertions(+), 33 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 255a318..03b8529 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3625,14 +3625,39 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
}

/*
- * Mark the task runnable and perform wakeup-preemption.
+ * Mark the task runnable.
*/
-static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
- struct rq_flags *rf)
+static inline void ttwu_do_wakeup(struct task_struct *p)
{
- check_preempt_curr(rq, p, wake_flags);
WRITE_ONCE(p->__state, TASK_RUNNING);
trace_sched_wakeup(p);
+}
+
+static void
+ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
+ struct rq_flags *rf)
+{
+ int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
+
+ lockdep_assert_rq_held(rq);
+
+ if (p->sched_contributes_to_load)
+ rq->nr_uninterruptible--;
+
+#ifdef CONFIG_SMP
+ if (wake_flags & WF_MIGRATED)
+ en_flags |= ENQUEUE_MIGRATED;
+ else
+#endif
+ if (p->in_iowait) {
+ delayacct_blkio_end(p);
+ atomic_dec(&task_rq(p)->nr_iowait);
+ }
+
+ activate_task(rq, p, en_flags);
+ check_preempt_curr(rq, p, wake_flags);
+
+ ttwu_do_wakeup(p);

#ifdef CONFIG_SMP
if (p->sched_class->task_woken) {
@@ -3662,31 +3687,6 @@ static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
#endif
}

-static void
-ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
- struct rq_flags *rf)
-{
- int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
-
- lockdep_assert_rq_held(rq);
-
- if (p->sched_contributes_to_load)
- rq->nr_uninterruptible--;
-
-#ifdef CONFIG_SMP
- if (wake_flags & WF_MIGRATED)
- en_flags |= ENQUEUE_MIGRATED;
- else
-#endif
- if (p->in_iowait) {
- delayacct_blkio_end(p);
- atomic_dec(&task_rq(p)->nr_iowait);
- }
-
- activate_task(rq, p, en_flags);
- ttwu_do_wakeup(rq, p, wake_flags, rf);
-}
-
/*
* Consider @p being inside a wait loop:
*
@@ -3728,8 +3728,7 @@ static int ttwu_runnable(struct task_struct *p, int wake_flags)
update_rq_clock(rq);
check_preempt_curr(rq, p, wake_flags);
}
- WRITE_ONCE(p->__state, TASK_RUNNING);
- trace_sched_wakeup(p);
+ ttwu_do_wakeup(p);
ret = 1;
}
__task_rq_unlock(rq, &rf);
@@ -4095,8 +4094,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
goto out;

trace_sched_waking(p);
- WRITE_ONCE(p->__state, TASK_RUNNING);
- trace_sched_wakeup(p);
+ ttwu_do_wakeup(p);
goto out;
}

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