linux-kernel - Re: [PATCH] mm/filemap.c: unconditionally call mark_page

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Message-ID: <45F991E5.1060001@redhat.com>
Date:	Thu, 15 Mar 2007 14:35:17 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Valdis.Kletnieks@...edu
CC:	Andreas Mohr <andi@...x01.fht-esslingen.de>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>,
	Ashif Harji <asharji@...uwaterloo.ca>, linux-mm@...ck.org,
	Nick Piggin <npiggin@...e.de>, Jan Kara <jack@...e.cz>,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH] mm/filemap.c: unconditionally call mark_page_accessed

Valdis.Kletnieks@...edu wrote:
> On Wed, 14 Mar 2007 22:33:17 BST, Andreas Mohr said:
> 
>> it'd seem we need some kind of state management here to figure out good
>> intervals of when to call mark_page_accessed() *again* for this page. E.g.
>> despite non-changing access patterns you could still call mark_page_accessed(
> )
>> every 32 calls or so to avoid expiry, but this would need extra helper
>> variables.
> 
> What if you did something like
> 
> 	if (jiffies%32) {...
> 
> (Possibly scaling it so the low-order bits change).  No need to lock it, as
> "right most of the time" is close enough.

Bad idea.  That way you would only count page accesses if the
phase of the moon^Wjiffie is just right.

-- 
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