Demand based switching with RHEL4 on PE 1850 and 1950 servers

[Billinghurst, David (RTATECH)]

> From: David Billinghurst
>
> As part of our corporate energy efficiency program, I want to 
> reduce the energy consumption of our 1850 and 1950 servers.
> 
> ...
> 
> Is anyone using Demand-Based Switching, as discussed in
> http://www.dell.com/downloads/global/power/ps3q05-20050136-Hargrave-OE.pdf
> Will it work?  Is it a "Good Thing"?  Are there any other references?

Tried this on a PE1950 with two 3 GHz Xeon 5160 cpus (two socket x dual)
and 16 GB of RAM.  Just rebooted and enabled demand based switching
in the BIOS.  I just toggled the cpu frequency up and down, sending 
SIGUSR1 and SIGUSR2 to the cpuspeed daemon.

It all just worked, but the results are not what I expected.
 - at 3.00 GHz the server draws 271 +/- 2 W
 - at 2.00 GHz the server draws 267 +/- 2 W
This was quite repeatable, but hardly worthwhile.

I was expecting a larger change.  May upgrade an 1850 to RHEL4 and try that.

	David


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