sched: sched_rt_entity

Move the task_struct members specific to rt scheduling together.
A future optimization could be to put sched_entity and sched_rt_entity
into a union.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/init_task.h

@@ -133,9 +133,10 @@ extern struct group_info init_groups;
 	.nr_cpus_allowed = NR_CPUS,					\
 	.mm		= NULL,						\
 	.active_mm	= &init_mm,					\
-	.run_list	= LIST_HEAD_INIT(tsk.run_list),			\
+	.rt		= {						\
+		.run_list	= LIST_HEAD_INIT(tsk.rt.run_list),	\
+		.time_slice	= HZ, },				\
 	.ioprio		= 0,						\
-	.time_slice	= HZ,						\
 	.tasks		= LIST_HEAD_INIT(tsk.tasks),			\
 	.ptrace_children= LIST_HEAD_INIT(tsk.ptrace_children),		\
 	.ptrace_list	= LIST_HEAD_INIT(tsk.ptrace_list),		\

include/linux/sched.h

@@ -929,6 +929,11 @@ struct sched_entity {
 #endif
 };
 
+struct sched_rt_entity {
+	struct list_head run_list;
+	unsigned int time_slice;
+};
+
 struct task_struct {
 	volatile long state;	/* -1 unrunnable, 0 runnable, >0 stopped */
 	void *stack;
@@ -945,9 +950,9 @@ struct task_struct {
 #endif
 
 	int prio, static_prio, normal_prio;
-	struct list_head run_list;
 	const struct sched_class *sched_class;
 	struct sched_entity se;
+	struct sched_rt_entity rt;
 
 #ifdef CONFIG_PREEMPT_NOTIFIERS
 	/* list of struct preempt_notifier: */
@@ -972,7 +977,6 @@ struct task_struct {
 	unsigned int policy;
 	cpumask_t cpus_allowed;
 	int nr_cpus_allowed;
-	unsigned int time_slice;
 
 #ifdef CONFIG_PREEMPT_RCU
 	int rcu_read_lock_nesting;

kernel/sched.c

@@ -1685,7 +1685,7 @@ static void __sched_fork(struct task_struct *p)
 	p->se.wait_max			= 0;
 #endif
 
-	INIT_LIST_HEAD(&p->run_list);
+	INIT_LIST_HEAD(&p->rt.run_list);
 	p->se.on_rq = 0;
 
 #ifdef CONFIG_PREEMPT_NOTIFIERS

kernel/sched_rt.c

@@ -111,7 +111,7 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
 {
 	struct rt_prio_array *array = &rq->rt.active;
 
-	list_add_tail(&p->run_list, array->queue + p->prio);
+	list_add_tail(&p->rt.run_list, array->queue + p->prio);
 	__set_bit(p->prio, array->bitmap);
 	inc_cpu_load(rq, p->se.load.weight);
 
@@ -127,7 +127,7 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
 
 	update_curr_rt(rq);
 
-	list_del(&p->run_list);
+	list_del(&p->rt.run_list);
 	if (list_empty(array->queue + p->prio))
 		__clear_bit(p->prio, array->bitmap);
 	dec_cpu_load(rq, p->se.load.weight);
@@ -143,7 +143,7 @@ static void requeue_task_rt(struct rq *rq, struct task_struct *p)
 {
 	struct rt_prio_array *array = &rq->rt.active;
 
-	list_move_tail(&p->run_list, array->queue + p->prio);
+	list_move_tail(&p->rt.run_list, array->queue + p->prio);
 }
 
 static void
@@ -212,7 +212,7 @@ static struct task_struct *pick_next_task_rt(struct rq *rq)
 		return NULL;
 
 	queue = array->queue + idx;
-	next = list_entry(queue->next, struct task_struct, run_list);
+	next = list_entry(queue->next, struct task_struct, rt.run_list);
 
 	next->se.exec_start = rq->clock;
 
@@ -261,14 +261,14 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
 	queue = array->queue + idx;
 	BUG_ON(list_empty(queue));
 
-	next = list_entry(queue->next, struct task_struct, run_list);
+	next = list_entry(queue->next, struct task_struct, rt.run_list);
 	if (unlikely(pick_rt_task(rq, next, cpu)))
 		goto out;
 
 	if (queue->next->next != queue) {
 		/* same prio task */
 		next = list_entry(queue->next->next, struct task_struct,
-				  run_list);
+				  rt.run_list);
 		if (pick_rt_task(rq, next, cpu))
 			goto out;
 	}
@@ -282,7 +282,7 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
 	queue = array->queue + idx;
 	BUG_ON(list_empty(queue));
 
-	list_for_each_entry(next, queue, run_list) {
+	list_for_each_entry(next, queue, rt.run_list) {
 		if (pick_rt_task(rq, next, cpu))
 			goto out;
 	}
@@ -846,16 +846,16 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p)
 	if (p->policy != SCHED_RR)
 		return;
 
-	if (--p->time_slice)
+	if (--p->rt.time_slice)
 		return;
 
-	p->time_slice = DEF_TIMESLICE;
+	p->rt.time_slice = DEF_TIMESLICE;
 
 	/*
 	 * Requeue to the end of queue if we are not the only element
 	 * on the queue:
 	 */
-	if (p->run_list.prev != p->run_list.next) {
+	if (p->rt.run_list.prev != p->rt.run_list.next) {
 		requeue_task_rt(rq, p);
 		set_tsk_need_resched(p);
 	}

mm/oom_kill.c

@@ -286,7 +286,7 @@ static void __oom_kill_task(struct task_struct *p, int verbose)
 	 * all the memory it needs. That way it should be able to
 	 * exit() and clear out its resources quickly...
 	 */
-	p->time_slice = HZ;
+	p->rt.time_slice = HZ;
 	set_tsk_thread_flag(p, TIF_MEMDIE);
 
 	force_sig(SIGKILL, p);