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Date: Sat, 01 Dec 2001 12:22:22 +0300
From: Hans Reiser <reiser@namesys.com>
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To: Marcelo Tosatti <marcelo@conectiva.com.br>
CC: Andrew Morton <akpm@zip.com.au>, Linus Torvalds <torvalds@transmeta.com>,
        lkml <linux-kernel@vger.kernel.org>,
        reiserfs-dev <reiserfs-dev@namesys.com>
Subject: Re: [patch] smarter atime updates
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Marcelo Tosatti wrote:

>Now are you sure this can't break anything ? 
>
>On Thu, 29 Nov 2001, Andrew Morton wrote:
>
>>mark_inode_dirty() is quite expensive for journalling filesystems,
>>and we're calling it a lot more than we need to.
>>
>>--- linux-2.4.17-pre1/fs/inode.c	Mon Nov 26 11:52:07 2001
>>+++ linux-akpm/fs/inode.c	Thu Nov 29 21:53:02 2001
>>@@ -1187,6 +1187,8 @@ void __init inode_init(unsigned long mem
>>  
>> void update_atime (struct inode *inode)
>> {
>>+	if (inode->i_atime == CURRENT_TIME)
>>+		return;
>> 	if ( IS_NOATIME (inode) ) return;
>> 	if ( IS_NODIRATIME (inode) && S_ISDIR (inode->i_mode) ) return;
>> 	if ( IS_RDONLY (inode) ) return;
>>
>>
>>with this patch, the time to read a 10 meg file with 10 million
>>read()s falls from 38 seconds (ext3), 39 seconds (reiserfs) and
>>11.6 seconds (ext2) down to 10.5 seconds.
>>
>>-
>>
>
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>
nice optimization.

Hans