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Date: Thu, 5 Dec 2002 22:00:51 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@digeo.com>
Cc: Andrea Arcangeli <andrea@suse.de>, Norman Gaywood <norm@turing.une.edu.au>,
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Subject: Re: Maybe a VM bug in 2.4.18-18 from RH 8.0?
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William Lee Irwin III wrote:
>> Yes, it's necessary; no, I've never directly encountered the issue it
>> fixes. Sorry about the miscommunication there.

On Thu, Dec 05, 2002 at 09:25:15PM -0800, Andrew Morton wrote:
> Linus's approach was to raise the ZONE_NORMAL pages_min limit for
> allocations which _could_ use highmem.  So a GFP_HIGHUSER allocation
> has a pages_min limit of (say) 4M when considering the normal zone,
> but a GFP_KERNEL allocation has a limit of 2M.
> Andrea's patch does the same thing, via a separate table.   He has
> set the threshold much higher (100M on a 4G box).   AFAICT, the
> algorithms are identical - I was planning on just adding a multiplier
> to set Linus's ratio - it is currently hardwired to "1".   Search for 
> "mysterious" in mm/page_alloc.c ;)

There's no mystery here aside from a couple of magic numbers and a
not-very-well-explained admission control policy.

Tweaking magic numbers a la 2.4.x-aa until more infrastructure is
available (2.7) sounds good to me.

Thanks,
Bill
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