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plist: Shrink struct plist_head

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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>
This commit is contained in:
Lai Jiangshan
2010-12-21 17:55:14 +08:00
committed by Steven Rostedt
parent 017f2b239d
commit bf6a9b8336
2 changed files with 59 additions and 42 deletions
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47
include/linux/plist.h
View File

@@ -31,15 +31,17 @@
* *
* Simple ASCII art explanation: * Simple ASCII art explanation:
* *
* |HEAD | * pl:prio_list (only for plist_node)
* | | * nl:node_list
* |prio_list.prev|<------------------------------------| * HEAD| NODE(S)
* |prio_list.next|<->|pl|<->|pl|<--------------->|pl|<-| * |
* |10 | |10| |21| |21| |21| |40| (prio) * ||------------------------------------|
* | | | | | | | | | | | | * ||->|pl|<->|pl|<--------------->|pl|<-|
* | | | | | | | | | | | | * | |10| |21| |21| |21| |40| (prio)
* |node_list.next|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-| * | | | | | | | | | | |
* |node_list.prev|<------------------------------------| * | | | | | | | | | | |
* |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
* |-------------------------------------------|
* *
* The nodes on the prio_list list are sorted by priority to simplify * The nodes on the prio_list list are sorted by priority to simplify
* the insertion of new nodes. There are no nodes with duplicate * the insertion of new nodes. There are no nodes with duplicate
@@ -78,7 +80,6 @@
#include <linux/spinlock_types.h> #include <linux/spinlock_types.h>
struct plist_head { struct plist_head {
struct list_head prio_list;
struct list_head node_list; struct list_head node_list;
#ifdef CONFIG_DEBUG_PI_LIST #ifdef CONFIG_DEBUG_PI_LIST
raw_spinlock_t *rawlock; raw_spinlock_t *rawlock;
@@ -88,7 +89,8 @@ struct plist_head {
struct plist_node { struct plist_node {
int prio; int prio;
struct plist_head plist; struct list_head prio_list;
struct list_head node_list;
}; };
#ifdef CONFIG_DEBUG_PI_LIST #ifdef CONFIG_DEBUG_PI_LIST
@@ -100,7 +102,6 @@ struct plist_node {
#endif #endif
#define _PLIST_HEAD_INIT(head) \ #define _PLIST_HEAD_INIT(head) \
.prio_list = LIST_HEAD_INIT((head).prio_list), \
.node_list = LIST_HEAD_INIT((head).node_list) .node_list = LIST_HEAD_INIT((head).node_list)
/** /**
@@ -133,7 +134,8 @@ struct plist_node {
#define PLIST_NODE_INIT(node, __prio) \ #define PLIST_NODE_INIT(node, __prio) \
{ \ { \
.prio = (__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 static inline void
plist_head_init(struct plist_head *head, spinlock_t *lock) plist_head_init(struct plist_head *head, spinlock_t *lock)
{ {
INIT_LIST_HEAD(&head->prio_list);
INIT_LIST_HEAD(&head->node_list); INIT_LIST_HEAD(&head->node_list);
#ifdef CONFIG_DEBUG_PI_LIST #ifdef CONFIG_DEBUG_PI_LIST
head->spinlock = lock; head->spinlock = lock;
@@ -160,7 +161,6 @@ plist_head_init(struct plist_head *head, spinlock_t *lock)
static inline void static inline void
plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock) plist_head_init_raw(struct plist_head *head, raw_spinlock_t *lock)
{ {
INIT_LIST_HEAD(&head->prio_list);
INIT_LIST_HEAD(&head->node_list); INIT_LIST_HEAD(&head->node_list);
#ifdef CONFIG_DEBUG_PI_LIST #ifdef CONFIG_DEBUG_PI_LIST
head->rawlock = lock; 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) static inline void plist_node_init(struct plist_node *node, int prio)
{ {
node->prio = 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); 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 * @head: the head for your list
*/ */
#define plist_for_each(pos, head) \ #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 * 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. * Iterate over a plist of given type, safe against removal of list entry.
*/ */
#define plist_for_each_safe(pos, n, head) \ #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 * 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 * @mem: the name of the list_struct within the struct
*/ */
#define plist_for_each_entry(pos, head, mem) \ #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 * 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. * Iterate over list of given type, safe against removal of list entry.
*/ */
#define plist_for_each_entry_safe(pos, n, head, m) \ #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 * 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) 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. */ /* 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) static inline struct plist_node *plist_first(const struct plist_head *head)
{ {
return list_entry(head->node_list.next, 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) static inline struct plist_node *plist_last(const struct plist_head *head)
{ {
return list_entry(head->node_list.prev, return list_entry(head->node_list.prev,
struct plist_node, plist.node_list); struct plist_node, node_list);
} }
#endif #endif

54
lib/plist.c
View File

@@ -59,7 +59,8 @@ static void plist_check_head(struct plist_head *head)
WARN_ON_SMP(!raw_spin_is_locked(head->rawlock)); WARN_ON_SMP(!raw_spin_is_locked(head->rawlock));
if (head->spinlock) if (head->spinlock)
WARN_ON_SMP(!spin_is_locked(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); 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) 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); plist_check_head(head);
WARN_ON(!plist_node_empty(node)); 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 (plist_head_empty(head))
if (node->prio < iter->prio) goto ins_node;
goto lt_prio;
else if (node->prio == iter->prio) { first = iter = plist_first(head);
iter = list_entry(iter->plist.prio_list.next,
struct plist_node, plist.prio_list); do {
goto eq_prio; if (node->prio < iter->prio) {
node_next = &iter->node_list;
break;
} }
}
lt_prio: prev = iter;
list_add_tail(&node->plist.prio_list, &iter->plist.prio_list); iter = list_entry(iter->prio_list.next,
eq_prio: struct plist_node, prio_list);
list_add_tail(&node->plist.node_list, &iter->plist.node_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); plist_check_head(head);
} }
@@ -108,14 +117,21 @@ void plist_del(struct plist_node *node, struct plist_head *head)
{ {
plist_check_head(head); plist_check_head(head);
if (!list_empty(&node->plist.prio_list)) { if (!list_empty(&node->prio_list)) {
struct plist_node *next = plist_first(&node->plist); if (node->node_list.next != &head->node_list) {
struct plist_node *next;
list_move_tail(&next->plist.prio_list, &node->plist.prio_list); next = list_entry(node->node_list.next,
list_del_init(&node->plist.prio_list); 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); plist_check_head(head);
} }