Andrew> On Fri, 5 Oct 2007 15:02:22 -0400, John Stoffel wrote:

quoted

How much memory does this system have?  Have you checked the output of

Andrew> 2GB

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/proc/mtrr at all?  There' have been reports of systems with a bad

Andrew> $ cat /proc/mtrr 
Andrew> reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1

That looks to be good, all the memory is there all in the same
region.  Oh well... it was a thought. 

quoted

BIOS that gets the memory map wrong, causing access to memory to slow
down drastically.

Andrew> BIOS-provided physical RAM map:
Andrew>  BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
Andrew>  BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
Andrew>  BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
Andrew>  BIOS-e820: 0000000000100000 - 000000007fff0000 (usable)
Andrew>  BIOS-e820: 000000007fff0000 - 000000007ffff000 (ACPI data)
Andrew>  BIOS-e820: 000000007ffff000 - 0000000080000000 (ACPI NVS)
Andrew>  BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)

I dunno about this part.  

Andrew> full dmesg (from 2.6.21-rc8-git2) at
Andrew> http://digital-domain.net/kernel/sw-raid5-issue/dmesg

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So if you have 2gb of RAM, try booting with mem=1900m or something

Andrew> Worth a shot.

It might make a difference, might not.  Do you have any kernel
debugging options turned on?  That might also be an issue.  Check your
.config, there are a couple of options which drastically slow down the
system. 

quoted

like that and seeing if things are better for you.

Make sure your BIOS is upto the latest level as well.

Andrew> Hmm, I'll see whats involved in that.
 
At this point, I don't suspect the BIOS any more.  

Can you start a 'vmstat 1' in one window, then start whatever you do
to get crappy performance.  That would be interesting to see.

John