sched/deadline: replace earliest dl and rq leftmost caching

... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-9-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 21 insertions, 35 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 9e38df7649f4..0191ec7667c3 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -296,7 +296,7 @@ static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
 {
         struct sched_dl_entity *dl_se = &p->dl;
 
-        return dl_rq->rb_leftmost == &dl_se->rb_node;
+        return dl_rq->root.rb_leftmost == &dl_se->rb_node;
 }
 
 void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
@@ -320,7 +320,7 @@ void init_dl_bw(struct dl_bw *dl_b)
 
 void init_dl_rq(struct dl_rq *dl_rq)
 {
-        dl_rq->rb_root = RB_ROOT;
+        dl_rq->root = RB_ROOT_CACHED;
 
 #ifdef CONFIG_SMP
         /* zero means no -deadline tasks */
@@ -328,7 +328,7 @@ void init_dl_rq(struct dl_rq *dl_rq)
 
         dl_rq->dl_nr_migratory = 0;
         dl_rq->overloaded = 0;
-        dl_rq->pushable_dl_tasks_root = RB_ROOT;
+        dl_rq->pushable_dl_tasks_root = RB_ROOT_CACHED;
 #else
         init_dl_bw(&dl_rq->dl_bw);
 #endif
@@ -410,10 +410,10 @@ static void dec_dl_migration(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
 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_node;
+        struct rb_node **link = &dl_rq->pushable_dl_tasks_root.rb_root.rb_node;
         struct rb_node *parent = NULL;
         struct task_struct *entry;
-        int leftmost = 1;
+        bool leftmost = true;
 
         BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
 
@@ -425,17 +425,16 @@ static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
                         link = &parent->rb_left;
                 else {
                         link = &parent->rb_right;
-                        leftmost = 0;
+                        leftmost = false;
                 }
         }
 
-        if (leftmost) {
-                dl_rq->pushable_dl_tasks_leftmost = &p->pushable_dl_tasks;
+        if (leftmost)
                 dl_rq->earliest_dl.next = p->dl.deadline;
-        }
 
         rb_link_node(&p->pushable_dl_tasks, parent, link);
-        rb_insert_color(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
+        rb_insert_color_cached(&p->pushable_dl_tasks,
+                               &dl_rq->pushable_dl_tasks_root, leftmost);
 }
 
 static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
@@ -445,24 +444,23 @@ static void dequeue_pushable_dl_task(struct rq *rq, struct task_struct *p)
         if (RB_EMPTY_NODE(&p->pushable_dl_tasks))
                 return;
 
-        if (dl_rq->pushable_dl_tasks_leftmost == &p->pushable_dl_tasks) {
+        if (dl_rq->pushable_dl_tasks_root.rb_leftmost == &p->pushable_dl_tasks) {
                 struct rb_node *next_node;
 
                 next_node = rb_next(&p->pushable_dl_tasks);
-                dl_rq->pushable_dl_tasks_leftmost = next_node;
                 if (next_node) {
                         dl_rq->earliest_dl.next = rb_entry(next_node,
                                 struct task_struct, pushable_dl_tasks)->dl.deadline;
                 }
         }
 
-        rb_erase(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
+        rb_erase_cached(&p->pushable_dl_tasks, &dl_rq->pushable_dl_tasks_root);
         RB_CLEAR_NODE(&p->pushable_dl_tasks);
 }
 
 static inline int has_pushable_dl_tasks(struct rq *rq)
 {
-        return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root);
+        return !RB_EMPTY_ROOT(&rq->dl.pushable_dl_tasks_root.rb_root);
 }
 
 static int push_dl_task(struct rq *rq);
@@ -1266,7 +1264,7 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
                 dl_rq->earliest_dl.next = 0;
                 cpudl_clear(&rq->rd->cpudl, rq->cpu);
         } else {
-                struct rb_node *leftmost = dl_rq->rb_leftmost;
+                struct rb_node *leftmost = dl_rq->root.rb_leftmost;
                 struct sched_dl_entity *entry;
 
                 entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
@@ -1313,7 +1311,7 @@ void dec_dl_tasks(struct sched_dl_entity *dl_se, struct dl_rq *dl_rq)
 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->rb_root.rb_node;
+        struct rb_node **link = &dl_rq->root.rb_root.rb_node;
         struct rb_node *parent = NULL;
         struct sched_dl_entity *entry;
         int leftmost = 1;
@@ -1331,11 +1329,8 @@ static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
                 }
         }
 
-        if (leftmost)
-                dl_rq->rb_leftmost = &dl_se->rb_node;
-
         rb_link_node(&dl_se->rb_node, parent, link);
-        rb_insert_color(&dl_se->rb_node, &dl_rq->rb_root);
+        rb_insert_color_cached(&dl_se->rb_node, &dl_rq->root, leftmost);
 
         inc_dl_tasks(dl_se, dl_rq);
 }
@@ -1347,14 +1342,7 @@ static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
         if (RB_EMPTY_NODE(&dl_se->rb_node))
                 return;
 
-        if (dl_rq->rb_leftmost == &dl_se->rb_node) {
-                struct rb_node *next_node;
-
-                next_node = rb_next(&dl_se->rb_node);
-                dl_rq->rb_leftmost = next_node;
-        }
-
-        rb_erase(&dl_se->rb_node, &dl_rq->rb_root);
+        rb_erase_cached(&dl_se->rb_node, &dl_rq->root);
         RB_CLEAR_NODE(&dl_se->rb_node);
 
         dec_dl_tasks(dl_se, dl_rq);
@@ -1647,7 +1635,7 @@ static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
                                                    struct dl_rq *dl_rq)
 {
-        struct rb_node *left = dl_rq->rb_leftmost;
+        struct rb_node *left = rb_first_cached(&dl_rq->root);
 
         if (!left)
                 return NULL;
@@ -1771,7 +1759,7 @@ static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
  */
 static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq, int cpu)
 {
-        struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost;
+        struct rb_node *next_node = rq->dl.pushable_dl_tasks_root.rb_leftmost;
         struct task_struct *p = NULL;
 
         if (!has_pushable_dl_tasks(rq))
@@ -1945,7 +1933,7 @@ static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
         if (!has_pushable_dl_tasks(rq))
                 return NULL;
 
-        p = rb_entry(rq->dl.pushable_dl_tasks_leftmost,
+        p = rb_entry(rq->dl.pushable_dl_tasks_root.rb_leftmost,
                      struct task_struct, pushable_dl_tasks);
 
         BUG_ON(rq->cpu != task_cpu(p));
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c30c57563dbc..746ac78ff492 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -549,8 +549,7 @@ struct rt_rq {
 /* Deadline class' related fields in a runqueue */
 struct dl_rq {
         /* runqueue is an rbtree, ordered by deadline */
-        struct rb_root rb_root;
-        struct rb_node *rb_leftmost;
+        struct rb_root_cached root;
 
         unsigned long dl_nr_running;
 
@@ -574,8 +573,7 @@ struct dl_rq {
          * an rb-tree, ordered by tasks' deadlines, with caching
          * of the leftmost (earliest deadline) element.
          */
-        struct rb_root pushable_dl_tasks_root;
-        struct rb_node *pushable_dl_tasks_leftmost;
+        struct rb_root_cached pushable_dl_tasks_root;
 #else
         struct dl_bw dl_bw;
 #endif