[RFC PATCH v2 03/25] sched/deadline: Distinct between dl_rq and my_q

From: Yuri Andriaccio
Date: Thu Jul 31 2025 - 06:56:22 EST


From: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>

Create two fields for runqueues in sched_dl_entity to make a distinction between
the global runqueue and the runqueue which the dl_server serves.

Signed-off-by: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
Signed-off-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
---
include/linux/sched.h | 6 ++++--
kernel/sched/deadline.c | 11 +++++++----
kernel/sched/fair.c | 6 +++---
kernel/sched/sched.h | 3 ++-
4 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 40d2fa90df4..f0c8229afd1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -724,12 +724,14 @@ struct sched_dl_entity {
* Bits for DL-server functionality. Also see the comment near
* dl_server_update().
*
- * @rq the runqueue this server is for
+ * @dl_rq the runqueue on which this entity is (to be) queued
+ * @my_q the runqueue "owned" by this entity
*
* @server_has_tasks() returns true if @server_pick return a
* runnable task.
*/
- struct rq *rq;
+ struct dl_rq *dl_rq;
+ struct rq *my_q;
dl_server_has_tasks_f server_has_tasks;
dl_server_pick_f server_pick_task;

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 46b9b78cca2..73ca5c0a086 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -75,11 +75,12 @@ static inline struct rq *rq_of_dl_rq(struct dl_rq *dl_rq)

static inline struct rq *rq_of_dl_se(struct sched_dl_entity *dl_se)
{
- struct rq *rq = dl_se->rq;
+ struct rq *rq;

if (!dl_server(dl_se))
rq = task_rq(dl_task_of(dl_se));
-
+ else
+ rq = container_of(dl_se->dl_rq, struct rq, dl);
return rq;
}

@@ -1641,11 +1642,13 @@ static bool dl_server_stopped(struct sched_dl_entity *dl_se)
return false;
}

-void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq,
+void dl_server_init(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq,
+ struct rq *served_rq,
dl_server_has_tasks_f has_tasks,
dl_server_pick_f pick_task)
{
- dl_se->rq = rq;
+ dl_se->dl_rq = dl_rq;
+ dl_se->my_q = served_rq;
dl_se->server_has_tasks = has_tasks;
dl_se->server_pick_task = pick_task;
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b173a059315..2723086538b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8861,12 +8861,12 @@ static struct task_struct *__pick_next_task_fair(struct rq *rq, struct task_stru

static bool fair_server_has_tasks(struct sched_dl_entity *dl_se)
{
- return !!dl_se->rq->cfs.nr_queued;
+ return !!dl_se->my_q->cfs.nr_queued;
}

static struct task_struct *fair_server_pick_task(struct sched_dl_entity *dl_se)
{
- return pick_task_fair(dl_se->rq);
+ return pick_task_fair(dl_se->my_q);
}

void fair_server_init(struct rq *rq)
@@ -8875,7 +8875,7 @@ void fair_server_init(struct rq *rq)

init_dl_entity(dl_se);

- dl_server_init(dl_se, rq, fair_server_has_tasks, fair_server_pick_task);
+ dl_server_init(dl_se, &rq->dl, rq, fair_server_has_tasks, fair_server_pick_task);
}

/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 8719ab8a817..a8073d0824d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -382,7 +382,8 @@ extern s64 dl_scaled_delta_exec(struct rq *rq, struct sched_dl_entity *dl_se, s6
extern void dl_server_update(struct sched_dl_entity *dl_se, s64 delta_exec);
extern void dl_server_start(struct sched_dl_entity *dl_se);
extern void dl_server_stop(struct sched_dl_entity *dl_se);
-extern void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq,
+extern void dl_server_init(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq,
+ struct rq *served_rq,
dl_server_has_tasks_f has_tasks,
dl_server_pick_f pick_task);
extern void sched_init_dl_servers(void);
--
2.50.1