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Date: Thu, 07 Mar 2002 14:23:21 -0800
From: Andrew Morton <akpm@zip.com.au>
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To: Rik van Riel <riel@conectiva.com.br>
CC: linux-kernel@vger.kernel.org
Subject: Re: [RFC] Arch option to touch newly allocated pages
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Rik van Riel wrote:
>
> > So what *is* a solution.  Well, there's only so much memory available.
> > In either case a) or case b) we're "fairly" distributing that memory
> > between all files.  And that's the problem.  *All* the files have too
> > small a readahead window.  Which points one at: we need to stop being
> > fair. We need to give some files a good readahead window and others
> > not.   The "soft pinning" which I propose with GFP_READAHEAD and
> > PG_readhead might have that effect, I think.
> 
> Actually, it could boil down to something more:
> 
> use-once reduces the VM to FIFO order, which suffers from
> belady's anomaly so it doesn't matter much how much memory
> you throw at it
> 
> drop-behind will suffer the same problem once the readahead
> memory is too large to keep in the system, but at least the
> already-used pages won't kick out readahead pages

err..  Was there a fix in there somewhere, or are we stuck?

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