From d74beb9f33a5f16d2965f11b275e401f225c949d Mon Sep 17 00:00:00 2001
From: Eric Dumazet <dada1@cosmosbay.com>
Date: Sat, 25 Mar 2006 03:08:19 -0800
Subject: [PATCH] [PATCH] Use unsigned int types for a faster bsearch
This patch avoids arithmetic on 'signed' types that are slower than
'unsigned'. This saves space and cpu cycles.
size of kernel/sys.o before the patch (gcc-3.4.5)
text data bss dec hex filename
10924 252 4 11180 2bac kernel/sys.o
size of kernel/sys.o after the patch
text data bss dec hex filename
10903 252 4 11159 2b97 kernel/sys.o
I noticed that gcc-4.1.0 (from Fedora Core 5) even uses idiv instruction for
(a+b)/2 if a and b are signed.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
kernel/sys.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index 119fb0d9e24e..38bc73ede2ba 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1363,7 +1363,7 @@ static void groups_sort(struct group_info *group_info)
/* a simple bsearch */
int groups_search(struct group_info *group_info, gid_t grp)
{
- int left, right;
+ unsigned int left, right;
if (!group_info)
return 0;
@@ -1371,7 +1371,7 @@ int groups_search(struct group_info *group_info, gid_t grp)
left = 0;
right = group_info->ngroups;
while (left < right) {
- int mid = (left+right)/2;
+ unsigned int mid = (left+right)/2;
int cmp = grp - GROUP_AT(group_info, mid);
if (cmp > 0)
left = mid + 1;