Commit b2d70222 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Add put_prev_task(.next) 



In order to tell the previous sched_class what the next task is, add
put_prev_task(.next).

Notable SCX will use this to:

 1) determine the next task will leave the SCX sched class and push
    the current task to another CPU if possible.
 2) statistics on how often and which other classes preempt it

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240813224016.367421076@infradead.org
parent bd9bbc96

kernel/sched/deadline.c

+1 −1
Original line number Diff line number Diff line
@@ -2436,7 +2436,7 @@ static struct task_struct *pick_task_dl(struct rq *rq) 
	return __pick_task_dl(rq);

}



static void put_prev_task_dl(struct rq *rq, struct task_struct *p)

static void put_prev_task_dl(struct rq *rq, struct task_struct *p, struct task_struct *next)

{

	struct sched_dl_entity *dl_se = &p->dl;

	struct dl_rq *dl_rq = &rq->dl;

kernel/sched/fair.c

+1 −1
Original line number Diff line number Diff line
@@ -8869,7 +8869,7 @@ void fair_server_init(struct rq *rq) 
/*

 * Account for a descheduled task:

 */

static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)

static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct task_struct *next)

{

	struct sched_entity *se = &prev->se;

	struct cfs_rq *cfs_rq;

kernel/sched/idle.c

+1 −1
Original line number Diff line number Diff line
@@ -450,7 +450,7 @@ static void wakeup_preempt_idle(struct rq *rq, struct task_struct *p, int flags) 
	resched_curr(rq);

}



static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)

static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct task_struct *next)

{

	dl_server_update_idle_time(rq, prev);

}

kernel/sched/rt.c

+1 −1
Original line number Diff line number Diff line
@@ -1748,7 +1748,7 @@ static struct task_struct *pick_task_rt(struct rq *rq) 
	return p;

}



static void put_prev_task_rt(struct rq *rq, struct task_struct *p)

static void put_prev_task_rt(struct rq *rq, struct task_struct *p, struct task_struct *next)

{

	struct sched_rt_entity *rt_se = &p->rt;

	struct rt_rq *rt_rq = &rq->rt;

kernel/sched/sched.h

+3 −3
Original line number Diff line number Diff line
@@ -2314,7 +2314,7 @@ struct sched_class { 
	 */

	struct task_struct *(*pick_next_task)(struct rq *rq, struct task_struct *prev);



	void (*put_prev_task)(struct rq *rq, struct task_struct *p);

	void (*put_prev_task)(struct rq *rq, struct task_struct *p, struct task_struct *next);

	void (*set_next_task)(struct rq *rq, struct task_struct *p, bool first);



#ifdef CONFIG_SMP
@@ -2364,7 +2364,7 @@ struct sched_class { 
static inline void put_prev_task(struct rq *rq, struct task_struct *prev)

{

	WARN_ON_ONCE(rq->curr != prev);

	prev->sched_class->put_prev_task(rq, prev);

	prev->sched_class->put_prev_task(rq, prev, NULL);

}



static inline void set_next_task(struct rq *rq, struct task_struct *next)
@@ -2393,7 +2393,7 @@ static inline void put_prev_set_next_task(struct rq *rq, 
	if (next == prev)

		return;



	prev->sched_class->put_prev_task(rq, prev);

	prev->sched_class->put_prev_task(rq, prev, next);

	next->sched_class->set_next_task(rq, next, true);

}