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Date: Thu, 5 Dec 2002 18:15:59 -0800
From: William Lee Irwin III <wli@holomorphy.com>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Andrew Morton <akpm@digeo.com>, 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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On Fri, Dec 06, 2002 at 02:44:29AM +0100, Andrea Arcangeli wrote:
> Or it hurts when you can't allocate an inode because such 100M are in
> pagetables on a 64G box and you still have 60G free of highmem.

This is the zone vs. zone watermark stuff that penalizes/fails
allocations made with a given GFP mask from being satisfied by
fallback. This is largely old news wrt. various kinds of inability
to pressure those ZONE_NORMAL (maybe also ZONE_DMA) consumers.

Admission control for fallback is valuable, sure. I suspect the
question akpm raised is about memory utilization. My own issues are
centered around allocations targeted directly at ZONE_NORMAL,
which fallback prevention does not address, so the watermark patch
is not something I'm personally very concerned about.

64GB isn't getting any testing that I know of; I'd hold off until
someone's actually stood up and confessed to attempting to boot
Linux on such a beast. Or until I get some more RAM. =)


Bill
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