[PATCH v12 4/7] sched: Add move_queued_task_locked helper

John Stultz
2024-08-13T23:57:51Z

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@layalina.io>
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: Mel Gorman <mgorman@suse.de>
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: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: kernel-team@android.com
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Metin Kaya <metin.kaya@arm.com>
Reviewed-by: Metin Kaya <metin.kaya@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
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>
---
v8:
* Renamed from push_task_chain to do_push_task so it makes
more sense without proxy-execution
v10:
* Changed name to move_queued_task_locked as suggested by Valentin
v11:
* Also use new helper in __migrate_swap_task() and
try_steal_cookie() as suggested by Qais Yousef
* Nit cleanups suggested by Metin
---
kernel/sched/core.c | 13 +++----------
kernel/sched/deadline.c | 8 ++------
kernel/sched/rt.c | 8 ++------
kernel/sched/sched.h | 12 ++++++++++++
4 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f3951e4a55e5b..b2cc20ed14de6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2526,9 +2526,7 @@ 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);
+ move_queued_task_locked(rq, lowest_rq, p);
resched_curr(lowest_rq);
}

@@ -3214,9 +3212,7 @@ static void __migrate_swap_task(struct task_struct *p, int cpu)
rq_pin_lock(src_rq, &srf);
rq_pin_lock(dst_rq, &drf);

- deactivate_task(src_rq, p, 0);
- set_task_cpu(p, cpu);
- activate_task(dst_rq, p, 0);
+ move_queued_task_locked(src_rq, dst_rq, p);
wakeup_preempt(dst_rq, p, 0);

rq_unpin_lock(dst_rq, &drf);
@@ -6152,10 +6148,7 @@ static bool try_steal_cookie(int this, int that)
if (sched_task_is_throttled(p, this))
goto next;

- deactivate_task(src, p, 0);
- set_task_cpu(p, this);
- activate_task(dst, p, 0);
-
+ move_queued_task_locked(src, dst, p);
resched_curr(dst);

success = true;
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f59e5c19d9445..ac60d2819bd1d 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2447,9 +2447,7 @@ 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);
+ move_queued_task_locked(rq, later_rq, next_task);
ret = 1;

resched_curr(later_rq);
@@ -2535,9 +2533,7 @@ 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);
+ move_queued_task_locked(src_rq, this_rq, p);
dmin = p->dl.deadline;
resched = true;
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 310523c1b9e3f..496d3e6ab57d2 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2105,9 +2105,7 @@ 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);
+ move_queued_task_locked(rq, lowest_rq, next_task);
resched_curr(lowest_rq);
ret = 1;

@@ -2378,9 +2376,7 @@ 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);
+ move_queued_task_locked(src_rq, this_rq, p);
resched = true;
}
/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4c36cc6803617..d2cc31c2457e5 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3575,6 +3575,18 @@ 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 move_queued_task_locked(struct rq *src_rq, struct rq *dst_rq, struct task_struct *task)
+{
+ lockdep_assert_rq_held(src_rq);
+ lockdep_assert_rq_held(dst_rq);
+
+ deactivate_task(src_rq, task, 0);
+ set_task_cpu(task, dst_rq->cpu);
+ activate_task(dst_rq, task, 0);
+}
+#endif

#ifdef CONFIG_RT_MUTEXES

--
2.46.0.76.ge559c4bf1a-goog