xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

list: remove prefetching from regular list iterators

Browse Source 
This is removes the use of software prefetching from the regular list
iterators.  We don't want it.  If you do want to prefetch in some
iterator of yours, go right ahead.  Just don't expect the iterator to do
it, since normally the downsides are bigger than the upsides.

It also replaces <linux/prefetch.h> with <linux/const.h>, because the
use of LIST_POISON ends up needing it.  <linux/poison.h> is sadly not
self-contained, and including prefetch.h just happened to hide that.

Suggested by David Miller (networking has a lot of regular lists that
are often empty or a single entry, and prefetching is not going to do
anything but add useless instructions).

Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2011-05-19 14:15:29 -07:00
parent 75d65a425c
commit e66eed651f
2 changed files with 14 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/rculist.h
View File

@@ -253,7 +253,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
*/
#define list_for_each_entry_rcu(pos, head, member) \
for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
prefetch(pos->member.next), &pos->member != (head); \
&pos->member != (head); \
pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
@@ -270,7 +270,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
*/
#define list_for_each_continue_rcu(pos, head) \
for ((pos) = rcu_dereference_raw(list_next_rcu(pos)); \
prefetch((pos)->next), (pos) != (head); \
(pos) != (head); \
(pos) = rcu_dereference_raw(list_next_rcu(pos)))
/**
@@ -284,7 +284,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
*/
#define list_for_each_entry_continue_rcu(pos, head, member) \
for (pos = list_entry_rcu(pos->member.next, typeof(*pos), member); \
prefetch(pos->member.next), &pos->member != (head); \
&pos->member != (head); \
pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
/**