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From: Russell King <rmk@arm.linux.org.uk>
To: Roger Larsson <roger.larsson@skelleftea.mail.telia.com>
Cc: Stephan von Krawczynski <skraw@ithnet.com>,
	Daniel Phillips <phillips@bonn-fries.net>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org
Subject: Re: [PATCH] __alloc_pages cleanup -R6 Was: Re: Memory Problem in 2.4.10-pre2 / __alloc_pages failed
Date: Fri, 31 Aug 2001 08:43:35 +0100	[thread overview]
Message-ID: <20010831084335.A4222@flint.arm.linux.org.uk> (raw)
In-Reply-To: <200108302357.BAA11235@mailb.telia.com>; from roger.larsson@skelleftea.mail.telia.com on Fri, Aug 31, 2001 at 01:53:24AM +0200

On Fri, Aug 31, 2001 at 01:53:24AM +0200, Roger Larsson wrote:
> Some ideas implemented in this code:
> * Reserve memory below min for atomic and recursive allocations.
> * When being min..low on free pages, free one more than you want to allocate.
> * When being low..high on free pages, free one less than wanted.
> * When above high - don't free anything.
> * First select zones with more than high free memory.
> * Then those with more than high 'free + inactive_clean - inactive_target'
> * When freeing - do it properly. Don't steal direct reclaimed pages

Hmm, I wonder.

I have a 1MB DMA zone, and 31MB of normal memory.

The machine has been running lots of programs for some time, but not under
any VM pressure.  I now come to open a device which requires 64K in 8K
pages from the DMA zone.  What happens?

I suspect that the chances of it failing will be significantly higher with
this algorithm - do you have any thoughts for this?

I don't think we should purely select the allocation zone based purely on
how much free it contains, but also if it's special (like the DMA zone).

You can't clean in-use slab pages out on demand like you can for fs
cache/user pages.

--
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html

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  reply	other threads:[~2001-08-31  7:43 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20010829140706.3fcb735c.skraw@ithnet.com>
     [not found] ` <20010829232929Z16206-32383+2351@humbolt.nl.linux.org>
     [not found]   ` <20010830164634.3706d8f8.skraw@ithnet.com>
2001-08-30 23:53     ` Roger Larsson
2001-08-31  7:43       ` Russell King [this message]
2001-08-31 23:22         ` Roger Larsson

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