[PATCH 2/3]fs/inode: iunique() Optimize Performance

["Liuweni" <qingshenlwy@gmail.com>]

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Change log:
Change the hash operation from division to shift. It will cost less time.
Also, I change the divisor from L1_CACHE_BYTES to L1_CACHE_SHIFT.
In the cache.h, the most L1_CACHE_BYTES defined as "(1 << L1_CACHE_SHIFT)".
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Signed-off-by: Liuwenyi<qingshenlwy@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Nick Piggin <npiggin@suse.de>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

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diff --git a/fs/inode.c b/fs/inode.c
index 4d8e3be..397d65f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -605,8 +605,8 @@ static unsigned long hash(struct super_block *sb, unsigned long hashval)
 {
 	unsigned long tmp;
 
-	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
-			L1_CACHE_BYTES;
+	tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) >>
+			L1_CACHE_SHIFT;
 	tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
 	return tmp & I_HASHMASK;
 }

 				
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Best Regards,
Liuweni
2009-11-25