RE: questions about DVFS in saving energy

["Tomas L. Byrnes" <tomb () byrneit net>]

Apologies for skirting close, but I think power consumption and heat
dissipation are pretty big operator costs, and anything we can do to
reduce those are beneficial to the bottom line; never mind the
environment. More below:

> -----Original Message-----
> From: Karl Southern [mailto:karl () theangryangel co uk]
> Sent: Thursday, May 14, 2009 1:10 AM
> To: Tomas L. Byrnes
> Cc: nanog () merit edu
> Subject: Re: questions about DVFS in saving energy
>
> Tomas L. Byrnes wrote:
> > Basically the CPU scaling on the host makes the guest OS fall apart.
> Apologies for the general noise (and even more apologies for stepping
> outside of the nanog scope), but if it's timing related issues does
> /usepmtimer not resolve this issue for the VMs? It certainly does on
> other virtualisation solutions.


[TLB:] We tried all the solutions we could Google, including
/usepmtimer. A potential 50% reduction in power per system (which is
what we were measuring in the tests) would be significant.
Unfortunately, it was not stable. It appears to be a Win2K3 issue,
although Red Hat Enterprise ran at the declock speed all the time, even
under heavy loads (it didn't crash and corrupt volumes like Win2K3,
however).