[Beowulf] Performance issue - CPU Intel 00/02

David Mathog mathog at mendel.bio.caltech.edu
Wed Jul 20 11:40:10 EDT 2005


Bill Wichser <bill at Princeton.EDU> wrote:

> System: 128 node Intel 2.4GHz P4
> MBO: Tyan S2099, i845E
> OS: RedHat 8.0, kernel  2.4.18-18.8.0 (but 2.4.20-28.8 changes nothing)

> 
> This summer, having more time to investigate the problem, I found that 
> some nodes exhibit this degradation after a power cycle while others 
> didn't. 

We have some Asus motherboards which drop the CPU speed to a 
"safe" value after a power failure or other unplanned shutdown
event.  The symptoms are exactly as you describe - perfectly good
machines mysteriously running much slower than other identical
machines.

It seems likely that the Tyan board may be doing something
similar.  Try getting into the BIOS on one of these and see what
it's done to the clock speed.  Unfortunately for the Asus boards
the only way to fix this is in the BIOS using the keyboard.  That
would be rather painful if you had 300 nodes to deal with.  You
might want to see if there is a switch in the Tyan BIOS to disable
this feature.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech
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