2003-05-08 03:05:04

by Perez-Gonzalez, Inaky

[permalink] [raw]
Subject: RE: Swap Compression



> From: jw schultz [mailto:[email protected]]
>
> While we're having thoughts, this thread keeps me thinking
> it would make sense to have a block device driver that would
> be assigned unused memory.
>
> I don't mean memory on video cards etc. I'm thinking of the
> 10% of RAM unused when 1GB systems are booted with MEM=900M
> because they run faster with HIGHMEM turned off.
>
> The primary use for this "device" would be high priority swap.
> Even with whatever overhead it takes to access it should be
> orders of magnitude faster than any spinning media.

This reminds me of some howto I saw somewhere of someway to
use the MTD drivers to access the unused video RAM and turn
it into swap (maybe with blkmtd?) ... probably it can be done
with that too.

I'd really love it ... I don't know if I can blame it on highmem
or not, but since I enabled it, my system 'feels' slower.

I?aky P?rez-Gonz?lez -- Not speaking for Intel -- all opinions are my own
(and my fault)


2003-05-08 07:54:45

by Jörn Engel

[permalink] [raw]
Subject: Re: Swap Compression

On Wed, 7 May 2003 20:17:32 -0700, Perez-Gonzalez, Inaky wrote:
>
> This reminds me of some howto I saw somewhere of someway to
> use the MTD drivers to access the unused video RAM and turn
> it into swap (maybe with blkmtd?) ... probably it can be done
> with that too.

Jupp, if you know the physical address range of the RAM, it's a piece
of cake. Except that the slram option parsing is not user-friendly,
with me being an examplary user.

For memory above 4GB, things are harder. Basically you'd have to write
a new mtd driver that copies some of the highmem code. Maybe a day or
two plus testing.

> I'd really love it ... I don't know if I can blame it on highmem
> or not, but since I enabled it, my system 'feels' slower.

Go ahead and try it. If it 'feels' faster, it should be possible to
benchmark your feeling into some numbers.

J?rn

--
Victory in war is not repetitious.
-- Sun Tzu