From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Liuweni" <qingshenlwy@gmail.com>
Subject: [PATCH 2/3]fs/inode: iunique() Optimize Performance
Date: Wed, 25 Nov 2009 22:12:19 +0800
Message-ID: <200911252212166092236@gmail.com>
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Cc: "viro" <viro@zeniv.linux.org.uk>,
	"akpm" <akpm@linux-foundation.org>, "jack" <jack@suse.cz>,
	"npiggin" <npiggin@suse.de>,
	"linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
	"linux-kernel" <linux-kernel@vger.kernel.org>,
	"strongzgy" <strongzgy@gmail.com>, "xgr178" <xgr178@163.com>,
	"Liu Hui" <onlyflyer@gmail.com>
To: "linux-kernel" <linux-kernel@vger.kernel.org>
Return-path: <linux-kernel-owner+glk-linux-kernel-3=40m.gmane.org-S964806AbZKYOIA@vger.kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org

---
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)".
---
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

---
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;
 }

 				
--------------
Best Regards,
Liuweni
2009-11-25