Fix for slow computer when >= 1 GiB RAM installed; mtrr hack. (Re: Slow slow slow.)

[Karl Hegbloom]

On Tue, 2006-03-07 at 22:16 +0100, Gabriel Jägenstedt wrote:
> Ubuntu is VERY slow, it can take up to 5 minutes to start apps like
> grip, gnomebaker and gkrellm, before I did a reinstall nothing was
> bogged down and flew by.

I have a laptop that slows way down when the kernel is compiled with
HIGH_MEM support and the laptop has 1 GiB of RAM installed.  It turns
out to be something the matter with how the 'mtrr' are set up...  I
still don't know if it's Linux' fault, or this particular laptop model.
It does not seem to happen on most other computers, but maybe yours has
the same problem?

One workaround is to boot with 'mem=1008m' on the kernel command line.
With that, it runs at full speed.  The other workaround, which gets me
another few megabytes of available RAM, is to install the attached
script into /etc/mkinitramfs/scripts/init-top/, and then regenerate the
initrd.img with:

 sudo update-initramfs -c -k $(uname -r)

Don't forget to remove the 'mem=1008m', so you really get the RAM back.

-- 
Karl Hegbloom <hegbloom at pdx.edu>
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