From: Oleg Nesterov <oleg@tv-sign.ru>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@osdl.org>
Subject: [PATCH] optimize prefetch() usage in list_for_each_xxx
Date: Sat, 25 Dec 2004 20:15:33 +0300 [thread overview]
Message-ID: <41CDA035.BF574176@tv-sign.ru> (raw)
Hello.
This patch changes list_for_each_xxx iterators
from:
for (pos = (head)->next, prefetch(pos->next);
pos != (head);
pos = pos->next, prefetch(pos->next))
to:
for (pos = (head)->next;
prefetch(pos->next), pos != (head);
pos = pos->next)
Reduces my vmlinux .text size by 4401 bytes.
Oleg.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 2.6.10/include/linux/list.h~ 2004-11-15 17:12:20.000000000 +0300
+++ 2.6.10/include/linux/list.h 2004-12-25 21:46:56.379911176 +0300
@@ -326,8 +326,8 @@
* @head: the head for your list.
*/
#define list_for_each(pos, head) \
- for (pos = (head)->next, prefetch(pos->next); pos != (head); \
- pos = pos->next, prefetch(pos->next))
+ for (pos = (head)->next; prefetch(pos->next), pos != (head); \
+ pos = pos->next)
/**
* __list_for_each - iterate over a list
@@ -348,8 +348,8 @@
* @head: the head for your list.
*/
#define list_for_each_prev(pos, head) \
- for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
- pos = pos->prev, prefetch(pos->prev))
+ for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \
+ pos = pos->prev)
/**
* list_for_each_safe - iterate over a list safe against removal of list entry
@@ -368,11 +368,9 @@
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member), \
- prefetch(pos->member.next); \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member), \
- prefetch(pos->member.next))
+ for (pos = list_entry((head)->next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* list_for_each_entry_reverse - iterate backwards over list of given type.
@@ -381,11 +379,9 @@
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_reverse(pos, head, member) \
- for (pos = list_entry((head)->prev, typeof(*pos), member), \
- prefetch(pos->member.prev); \
- &pos->member != (head); \
- pos = list_entry(pos->member.prev, typeof(*pos), member), \
- prefetch(pos->member.prev))
+ for (pos = list_entry((head)->prev, typeof(*pos), member); \
+ prefetch(pos->member.prev), &pos->member != (head); \
+ pos = list_entry(pos->member.prev, typeof(*pos), member))
/**
* list_prepare_entry - prepare a pos entry for use as a start point in
@@ -405,11 +401,9 @@
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_continue(pos, head, member) \
- for (pos = list_entry(pos->member.next, typeof(*pos), member), \
- prefetch(pos->member.next); \
- &pos->member != (head); \
- pos = list_entry(pos->member.next, typeof(*pos), member), \
- prefetch(pos->member.next))
+ for (pos = list_entry(pos->member.next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
@@ -434,8 +428,8 @@
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_rcu(pos, head) \
- for (pos = (head)->next, prefetch(pos->next); pos != (head); \
- pos = rcu_dereference(pos->next), prefetch(pos->next))
+ for (pos = (head)->next; prefetch(pos->next), pos != (head); \
+ pos = rcu_dereference(pos->next))
#define __list_for_each_rcu(pos, head) \
for (pos = (head)->next; pos != (head); \
@@ -467,12 +461,10 @@
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_entry_rcu(pos, head, member) \
- for (pos = list_entry((head)->next, typeof(*pos), member), \
- prefetch(pos->member.next); \
- &pos->member != (head); \
+ for (pos = list_entry((head)->next, typeof(*pos), member); \
+ prefetch(pos->member.next), &pos->member != (head); \
pos = rcu_dereference(list_entry(pos->member.next, \
- typeof(*pos), member)), \
- prefetch(pos->member.next))
+ typeof(*pos), member)))
/**
@@ -486,8 +478,8 @@
* as long as the traversal is guarded by rcu_read_lock().
*/
#define list_for_each_continue_rcu(pos, head) \
- for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \
- (pos) = rcu_dereference((pos)->next), prefetch((pos)->next))
+ for ((pos) = (pos)->next; prefetch((pos)->next), (pos) != (head); \
+ (pos) = rcu_dereference((pos)->next))
/*
* Double linked lists with a single pointer list head.
reply other threads:[~2004-12-25 16:13 UTC|newest]
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