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Commit bf6a9b83 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Steven Rostedt
Browse files

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: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4D107982.9090700@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 017f2b23

include/linux/plist.h

+24 −23
Original line number Diff line number Diff line
@@ -31,15 +31,17 @@ 
 *

 * Simple ASCII art explanation:

 *

 * |HEAD          |

 * |              |

 * |prio_list.prev|<------------------------------------|

 * |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-|

 * |10            |   |10|   |21|   |21|   |21|   |40|   (prio)

 * |              |   |  |   |  |   |  |   |  |   |  |

 * |              |   |  |   |  |   |  |   |  |   |  |

 * |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|

 * |node_list.prev|<------------------------------------|

 * pl:prio_list (only for plist_node)

 * nl:node_list

 *   HEAD|             NODE(S)

 *       |

 *       ||------------------------------------|

 *       ||->|pl|<->|pl|<--------------->|pl|<-|

 *       |   |10|   |21|   |21|   |21|   |40|   (prio)

 *       |   |  |   |  |   |  |   |  |   |  |

 *       |   |  |   |  |   |  |   |  |   |  |

 * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|

 * |-------------------------------------------|

 *

 * The nodes on the prio_list list are sorted by priority to simplify

 * the insertion of new nodes. There are no nodes with duplicate
@@ -78,7 +80,6 @@ 
#include <linux/spinlock_types.h>



struct plist_head {

	struct list_head prio_list;

	struct list_head node_list;

#ifdef CONFIG_DEBUG_PI_LIST

	raw_spinlock_t *rawlock;
@@ -88,7 +89,8 @@ struct plist_head { 


struct plist_node {

	int			prio;

	struct plist_head	plist;

	struct list_head	prio_list;

	struct list_head	node_list;

};



#ifdef CONFIG_DEBUG_PI_LIST
@@ -100,7 +102,6 @@ struct plist_node { 
#endif



#define _PLIST_HEAD_INIT(head)				\

	.prio_list = LIST_HEAD_INIT((head).prio_list),	\

	.node_list = LIST_HEAD_INIT((head).node_list)



/**
@@ -133,7 +134,8 @@ struct plist_node { 
#define PLIST_NODE_INIT(node, __prio)			\

{							\

	.prio  = (__prio),				\

	.plist = { _PLIST_HEAD_INIT((node).plist) },	\

	.prio_list = LIST_HEAD_INIT((node).prio_list),	\

	.node_list = LIST_HEAD_INIT((node).node_list),	\

}



/**
@@ -144,7 +146,6 @@ struct plist_node { 
static inline void

plist_head_init(struct plist_head *head, spinlock_t *lock)

{

	INIT_LIST_HEAD(&head->prio_list);

	INIT_LIST_HEAD(&head->node_list);

#ifdef CONFIG_DEBUG_PI_LIST

	head->spinlock = lock;
@@ -160,7 +161,6 @@ plist_head_init(struct plist_head *head, spinlock_t *lock) 
static inline void

plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)

{

	INIT_LIST_HEAD(&head->prio_list);

	INIT_LIST_HEAD(&head->node_list);

#ifdef CONFIG_DEBUG_PI_LIST

	head->rawlock = lock;
@@ -176,7 +176,8 @@ plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock) 
static inline void plist_node_init(struct plist_node *node, int prio)

{

	node->prio = prio;

	plist_head_init(&node->plist, NULL);

	INIT_LIST_HEAD(&node->prio_list);

	INIT_LIST_HEAD(&node->node_list);

}



extern void plist_add(struct plist_node *node, struct plist_head *head);
@@ -188,7 +189,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head); 
 * @head:	the head for your list

 */

#define plist_for_each(pos, head)	\

	 list_for_each_entry(pos, &(head)->node_list, plist.node_list)

	 list_for_each_entry(pos, &(head)->node_list, node_list)



/**

 * plist_for_each_safe - iterate safely over a plist of given type
@@ -199,7 +200,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head); 
 * Iterate over a plist of given type, safe against removal of list entry.

 */

#define plist_for_each_safe(pos, n, head)	\

	 list_for_each_entry_safe(pos, n, &(head)->node_list, plist.node_list)

	 list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)



/**

 * plist_for_each_entry	- iterate over list of given type
@@ -208,7 +209,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head); 
 * @mem:	the name of the list_struct within the struct

 */

#define plist_for_each_entry(pos, head, mem)	\

	 list_for_each_entry(pos, &(head)->node_list, mem.plist.node_list)

	 list_for_each_entry(pos, &(head)->node_list, mem.node_list)



/**

 * plist_for_each_entry_safe - iterate safely over list of given type
@@ -220,7 +221,7 @@ extern void plist_del(struct plist_node *node, struct plist_head *head); 
 * Iterate over list of given type, safe against removal of list entry.

 */

#define plist_for_each_entry_safe(pos, n, head, m)	\

	list_for_each_entry_safe(pos, n, &(head)->node_list, m.plist.node_list)

	list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list)



/**

 * plist_head_empty - return !0 if a plist_head is empty
@@ -237,7 +238,7 @@ static inline int plist_head_empty(const struct plist_head *head) 
 */

static inline int plist_node_empty(const struct plist_node *node)

{

	return plist_head_empty(&node->plist);

	return list_empty(&node->node_list);

}



/* All functions below assume the plist_head is not empty. */
@@ -285,7 +286,7 @@ static inline int plist_node_empty(const struct plist_node *node) 
static inline struct plist_node *plist_first(const struct plist_head *head)

{

	return list_entry(head->node_list.next,

			  struct plist_node, plist.node_list);

			  struct plist_node, node_list);

}



/**
@@ -297,7 +298,7 @@ static inline struct plist_node *plist_first(const struct plist_head *head) 
static inline struct plist_node *plist_last(const struct plist_head *head)

{

	return list_entry(head->node_list.prev,

			  struct plist_node, plist.node_list);

			  struct plist_node, node_list);

}



#endif

lib/plist.c

+35 −19
Original line number Diff line number Diff line
@@ -59,7 +59,8 @@ static void plist_check_head(struct plist_head *head) 
		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 @@ static void plist_check_head(struct plist_head *head) 
 */

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 @@ void plist_del(struct plist_node *node, struct plist_head *head) 
{

	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;



			next = list_entry(node->node_list.next,

					struct plist_node, node_list);



		list_move_tail(&next->plist.prio_list, &node->plist.prio_list);

		list_del_init(&node->plist.prio_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);

}