[PATCH v7 18/23] sched: Add push_task_chain helper

John Stultz
2023-12-20T00:19:35Z

From: Connor O'Brien <connoro@google.com>

Switch logic that deactivates, sets the task cpu,
and reactivates a task on a different rq to use a
helper that will be later extended to push entire
blocked task chains.

This patch was broken out from a larger chain migration
patch originally by Connor O'Brien.

Cc: Joel Fernandes <joelaf@google.com>
Cc: Qais Yousef <qyousef@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Zimuzo Ezeozue <zezeozue@google.com>
Cc: Youssef Esmat <youssefesmat@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Metin Kaya <Metin.Kaya@arm.com>
Cc: Xuewen Yan <xuewen.yan94@gmail.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@android.com
Signed-off-by: Connor O'Brien <connoro@google.com>
[jstultz: split out from larger chain migration patch]
Signed-off-by: John Stultz <jstultz@google.com>
---
kernel/sched/core.c | 4 +---
kernel/sched/deadline.c | 8 ++------
kernel/sched/rt.c | 8 ++------
kernel/sched/sched.h | 9 +++++++++
4 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0cd63bd0bdcd..0c212dcd4b7a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2721,9 +2721,7 @@ int push_cpu_stop(void *arg)

// XXX validate p is still the highest prio task
if (task_rq(p) == rq) {
- deactivate_task(rq, p, 0);
- set_task_cpu(p, lowest_rq->cpu);
- activate_task(lowest_rq, p, 0);
+ push_task_chain(rq, lowest_rq, p);
resched_curr(lowest_rq);
}

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 4f998549ea74..def1eb23318b 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2313,9 +2313,7 @@ static int push_dl_task(struct rq *rq)
goto retry;
}

- deactivate_task(rq, next_task, 0);
- set_task_cpu(next_task, later_rq->cpu);
- activate_task(later_rq, next_task, 0);
+ push_task_chain(rq, later_rq, next_task);
ret = 1;

resched_curr(later_rq);
@@ -2401,9 +2399,7 @@ static void pull_dl_task(struct rq *this_rq)
if (is_migration_disabled(p)) {
push_task = get_push_task(src_rq);
} else {
- deactivate_task(src_rq, p, 0);
- set_task_cpu(p, this_cpu);
- activate_task(this_rq, p, 0);
+ push_task_chain(src_rq, this_rq, p);
dmin = p->dl.deadline;
resched = true;
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a7b51a021111..cf0eb4aac613 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2128,9 +2128,7 @@ static int push_rt_task(struct rq *rq, bool pull)
goto retry;
}

- deactivate_task(rq, next_task, 0);
- set_task_cpu(next_task, lowest_rq->cpu);
- activate_task(lowest_rq, next_task, 0);
+ push_task_chain(rq, lowest_rq, next_task);
resched_curr(lowest_rq);
ret = 1;

@@ -2401,9 +2399,7 @@ static void pull_rt_task(struct rq *this_rq)
if (is_migration_disabled(p)) {
push_task = get_push_task(src_rq);
} else {
- deactivate_task(src_rq, p, 0);
- set_task_cpu(p, this_cpu);
- activate_task(this_rq, p, 0);
+ push_task_chain(src_rq, this_rq, p);
resched = true;
}
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 765ba10661de..19afe532771f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3546,5 +3546,14 @@ static inline void init_sched_mm_cid(struct task_struct *t) { }

extern u64 avg_vruntime(struct cfs_rq *cfs_rq);
extern int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se);
+#ifdef CONFIG_SMP
+static inline
+void push_task_chain(struct rq *rq, struct rq *dst_rq, struct task_struct *task)
+{
+ deactivate_task(rq, task, 0);
+ set_task_cpu(task, dst_rq->cpu);
+ activate_task(dst_rq, task, 0);
+}
+#endif

#endif /* _KERNEL_SCHED_SCHED_H */
--
2.43.0.472.g3155946c3a-goog