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rbtree, sched/deadline: Use rb_add_cached()

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Reduce rbtree boiler plate by using the new helpers.

Make rb_add_cached() / rb_erase_cached() return a pointer to the
leftmost node to aid in updating additional state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
This commit is contained in:
Peter Zijlstra 2020-04-29 17:04:41 +02:00 committed by Ingo Molnar
parent bf9be9a163
commit 8ecca39483
2 changed files with 42 additions and 53 deletions
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18
include/linux/rbtree.h
View file

@ -141,12 +141,18 @@ static inline void rb_insert_color_cached(struct rb_node *node,
rb_insert_color(node, &root->rb_root);
}
static inline void rb_erase_cached(struct rb_node *node,
struct rb_root_cached *root)
static inline struct rb_node *
rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
{
struct rb_node *leftmost = NULL;
if (root->rb_leftmost == node)
root->rb_leftmost = rb_next(node);
leftmost = root->rb_leftmost = rb_next(node);
rb_erase(node, &root->rb_root);
return leftmost;
}
static inline void rb_replace_node_cached(struct rb_node *victim,
@ -179,8 +185,10 @@ static inline void rb_replace_node_cached(struct rb_node *victim,
* @node: node to insert
* @tree: leftmost cached tree to insert @node into
* @less: operator defining the (partial) node order
*
* Returns @node when it is the new leftmost, or NULL.
*/
static __always_inline void
static __always_inline struct rb_node *
rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
bool (*less)(struct rb_node *, const struct rb_node *))
{
@ -200,6 +208,8 @@ rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
rb_link_node(node, parent, link);
rb_insert_color_cached(node, tree, leftmost);
return leftmost ? node : NULL;
}
/**

77
kernel/sched/deadline.c
View file

@ -517,58 +517,44 @@ static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
update_dl_migration(dl_rq);
}
#define __node_2_pdl(node) \
rb_entry((node), struct task_struct, pushable_dl_tasks)
static inline bool __pushable_less(struct rb_node *a, const struct rb_node *b)
{
return dl_entity_preempt(&__node_2_pdl(a)->dl, &__node_2_pdl(b)->dl);
}
/*
* The list of pushable -deadline task is not a plist, like in
* sched_rt.c, it is an rb-tree with tasks ordered by deadline.
*/
static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
{
struct dl_rq *dl_rq = &rq->dl;
struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node;
struct rb_node *parent = NULL;
struct task_struct *entry;
bool leftmost = true;
struct rb_node *leftmost;
BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
while (*link) {
parent = *link;
entry = rb_entry(parent, struct task_struct,
pushable_dl_tasks);
if (dl_entity_preempt(&p->dl, &entry->dl))
link = &parent->rb_left;
else {
link = &parent->rb_right;
leftmost = false;
}
}
leftmost = rb_add_cached(&p->pushable_dl_tasks,
&rq->dl.pushable_dl_tasks_root,
__pushable_less);
if (leftmost)
dl_rq->earliest_dl.next = p->dl.deadline;
rb_link_node(&p->pushable_dl_tasks, parent, link);
rb_insert_color_cached(&p->pushable_dl_tasks,
&dl_rq->pushable_dl_tasks_root, leftmost);
rq->dl.earliest_dl.next = p->dl.deadline;
}
static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
{
struct dl_rq *dl_rq = &rq->dl;
struct rb_root_cached *root = &dl_rq->pushable_dl_tasks_root;
struct rb_node *leftmost;
if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
return;
if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks) {
struct rb_node *next_node;
leftmost = rb_erase_cached(&p->pushable_dl_tasks, root);
if (leftmost)
dl_rq->earliest_dl.next = __node_2_pdl(leftmost)->dl.deadline;
next_node = rb_next(&p->pushable_dl_tasks);
if (next_node) {
dl_rq->earliest_dl.next = rb_entry(next_node,
struct task_struct, pushable_dl_tasks)->dl.deadline;
}
}
rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
RB_CLEAR_NODE(&p->pushable_dl_tasks);
}
@ -1478,29 +1464,21 @@ void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
dec_dl_migration(dl_se, dl_rq);
}
#define __node_2_dle(node) \
rb_entry((node), struct sched_dl_entity, rb_node)
static inline bool __dl_less(struct rb_node *a, const struct rb_node *b)
{
return dl_time_before(__node_2_dle(a)->deadline, __node_2_dle(b)->deadline);
}
static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
{
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
struct rb_node **link = &dl_rq->root.rb_root.rb_node;
struct rb_node *parent = NULL;
struct sched_dl_entity *entry;
int leftmost = 1;
BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
while (*link) {
parent = *link;
entry = rb_entry(parent, struct sched_dl_entity, rb_node);
if (dl_time_before(dl_se->deadline, entry->deadline))
link = &parent->rb_left;
else {
link = &parent->rb_right;
leftmost = 0;
}
}
rb_link_node(&dl_se->rb_node, parent, link);
rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost);
rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
inc_dl_tasks(dl_se, dl_rq);
}
@ -1513,6 +1491,7 @@ static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
return;
rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
RB_CLEAR_NODE(&dl_se->rb_node);
dec_dl_tasks(dl_se, dl_rq);