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sched/rt: Simplify pull_rt_task() logic and remove .leaf_rt_rq_list

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[ Peter, this is based off of some of my work, I ran it though a few
  tests and it passed. I also reviewed it, and added my SOB as I am
  somewhat a co-author to it. ]

Based on the patch by Steven Rostedt from previous year:

https://lkml.org/lkml/2012/4/18/517

1)Simplify pull_rt_task() logic: search in pushable tasks of dest runqueue.
The only pullable tasks are the tasks which are pushable in their local rq,
and no others.

2)Remove .leaf_rt_rq_list member of struct rt_rq and functions connected
with it: nobody uses it since now.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/287571370557898@web7d.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Kirill Tkhai 2013-06-07 15:37:43 -04:00 committed by Ingo Molnar
parent d81344c508
commit e23ee74777
2 changed files with 16 additions and 67 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

82
kernel/sched/rt.c
View file

@ -399,20 +399,6 @@ static inline struct task_group *next_task_group(struct task_group *tg)
(iter = next_task_group(iter)) && \
(rt_rq = iter->rt_rq[cpu_of(rq)]);)
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
list_add_rcu(&rt_rq->leaf_rt_rq_list,
&rq_of_rt_rq(rt_rq)->leaf_rt_rq_list);
}
static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
list_del_rcu(&rt_rq->leaf_rt_rq_list);
}
#define for_each_leaf_rt_rq(rt_rq, rq) \
list_for_each_entry_rcu(rt_rq, &rq->leaf_rt_rq_list, leaf_rt_rq_list)
#define for_each_sched_rt_entity(rt_se) \
for (; rt_se; rt_se = rt_se->parent)
@ -509,17 +495,6 @@ typedef struct rt_rq *rt_rq_iter_t;
#define for_each_rt_rq(rt_rq, iter, rq) \
for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
{
}
static inline void list_del_leaf_rt_rq(struct rt_rq *rt_rq)
{
}
#define for_each_leaf_rt_rq(rt_rq, rq) \
for (rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
#define for_each_sched_rt_entity(rt_se) \
for (; rt_se; rt_se = NULL)
@ -1066,9 +1041,6 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
return;
if (!rt_rq->rt_nr_running)
list_add_leaf_rt_rq(rt_rq);
if (head)
list_add(&rt_se->run_list, queue);
else
@ -1088,8 +1060,6 @@ static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
__clear_bit(rt_se_prio(rt_se), array->bitmap);
dec_rt_tasks(rt_se, rt_rq);
if (!rt_rq->rt_nr_running)
list_del_leaf_rt_rq(rt_rq);
}
/*
@ -1394,42 +1364,24 @@ static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
return 0;
}
/* Return the second highest RT task, NULL otherwise */
static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
/*
* Return the highest pushable rq's task, which is suitable to be executed
* on the cpu, NULL otherwise
*/
static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
{
struct task_struct *next = NULL;
struct sched_rt_entity *rt_se;
struct rt_prio_array *array;
struct rt_rq *rt_rq;
int idx;
struct plist_head *head = &rq->rt.pushable_tasks;
struct task_struct *p;
for_each_leaf_rt_rq(rt_rq, rq) {
array = &rt_rq->active;
idx = sched_find_first_bit(array->bitmap);
next_idx:
if (idx >= MAX_RT_PRIO)
continue;
if (next && next->prio <= idx)
continue;
list_for_each_entry(rt_se, array->queue + idx, run_list) {
struct task_struct *p;
if (!has_pushable_tasks(rq))
return NULL;
if (!rt_entity_is_task(rt_se))
continue;
p = rt_task_of(rt_se);
if (pick_rt_task(rq, p, cpu)) {
next = p;
break;
}
}
if (!next) {
idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1);
goto next_idx;
}
plist_for_each_entry(p, head, pushable_tasks) {
if (pick_rt_task(rq, p, cpu))
return p;
}
return next;
return NULL;
}
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
@ -1703,12 +1655,10 @@ static int pull_rt_task(struct rq *this_rq)
double_lock_balance(this_rq, src_rq);
/*
* Are there still pullable RT tasks?
* We can pull only a task, which is pushable
* on its rq, and no others.
*/
if (src_rq->rt.rt_nr_running <= 1)
goto skip;
p = pick_next_highest_task_rt(src_rq, this_cpu);
p = pick_highest_pushable_task(src_rq, this_cpu);
/*
* Do we have an RT task that preempts

1
kernel/sched/sched.h
View file

@ -361,7 +361,6 @@ struct rt_rq {
unsigned long rt_nr_boosted;
struct rq *rq;
struct list_head leaf_rt_rq_list;
struct task_group *tg;
#endif
};