plist: Shrink struct plist_head
struct plist_head is used in struct task_struct as well as struct
rtmutex. If we can make it smaller, it will also make these structures
smaller as well.
The field prio_list in struct plist_head is seldom used and we can get
its information from the plist_nodes. Removing this field will decrease
the size of plist_head by half.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4D107982.9090700@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/lib/plist.c b/lib/plist.c
index 1471988..8c614d0 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -59,7 +59,8 @@
WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
if (head->spinlock)
WARN_ON_SMP(!spin_is_locked(head->spinlock));
- plist_check_list(&head->prio_list);
+ if (!plist_head_empty(head))
+ plist_check_list(&plist_first(head)->prio_list);
plist_check_list(&head->node_list);
}
@@ -75,25 +76,33 @@
*/
void plist_add(struct plist_node *node, struct plist_head *head)
{
- struct plist_node *iter;
+ struct plist_node *first, *iter, *prev = NULL;
+ struct list_head *node_next = &head->node_list;
plist_check_head(head);
WARN_ON(!plist_node_empty(node));
+ WARN_ON(!list_empty(&node->prio_list));
- list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
- if (node->prio < iter->prio)
- goto lt_prio;
- else if (node->prio == iter->prio) {
- iter = list_entry(iter->plist.prio_list.next,
- struct plist_node, plist.prio_list);
- goto eq_prio;
+ if (plist_head_empty(head))
+ goto ins_node;
+
+ first = iter = plist_first(head);
+
+ do {
+ if (node->prio < iter->prio) {
+ node_next = &iter->node_list;
+ break;
}
- }
-lt_prio:
- list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
-eq_prio:
- list_add_tail(&node->plist.node_list, &iter->plist.node_list);
+ prev = iter;
+ iter = list_entry(iter->prio_list.next,
+ struct plist_node, prio_list);
+ } while (iter != first);
+
+ if (!prev || prev->prio != node->prio)
+ list_add_tail(&node->prio_list, &iter->prio_list);
+ins_node:
+ list_add_tail(&node->node_list, node_next);
plist_check_head(head);
}
@@ -108,14 +117,21 @@
{
plist_check_head(head);
- if (!list_empty(&node->plist.prio_list)) {
- struct plist_node *next = plist_first(&node->plist);
+ if (!list_empty(&node->prio_list)) {
+ if (node->node_list.next != &head->node_list) {
+ struct plist_node *next;
- list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
- list_del_init(&node->plist.prio_list);
+ next = list_entry(node->node_list.next,
+ struct plist_node, node_list);
+
+ /* add the next plist_node into prio_list */
+ if (list_empty(&next->prio_list))
+ list_add(&next->prio_list, &node->prio_list);
+ }
+ list_del_init(&node->prio_list);
}
- list_del_init(&node->plist.node_list);
+ list_del_init(&node->node_list);
plist_check_head(head);
}