HEADS UP: Release schedule for 2006

[Kevin Oberman]

> From: George Hartzell <hartzell at kestrel.alerce.com>
> Date: Fri, 16 Dec 2005 16:05:51 -0800
> 
> Kevin Oberman writes:
>  > [...]
>  > No. There is no conflict between Cx states and EST. Cx states specifies
>  > how deeply the CPU will sleep when idle. EST controls processor speed
>  > and voltage. In most cases, your REALLY want to use both of these. They
>  > are very significant in saving power. (Of course, USB tends to limit the
>  > effectiveness of Cx states. I need to run without USB to get really good
>  > battery life and to make suspend (S3) really ut power drain.
> 
> Can you expand a bit on that "Of course USB...".  What's the problem
> with USB?  Can one just kunload it before suspend?  
> 
> g.

Only a bit. I believe it is the polling activity of the USB driver that
causes the problem, but, if USB drivers are loaded, most systems will
never get to the "deeper" sleep levels. My T30 has 3 sleep level of
which C2 is only a very modest power savings over C1. C3 is a
significant savings, but it is never used if USB devices are present.

If you unload the drivers, you should be to lower levels. Take a look at
sysctl hw.acpi.cpu for detail and to see how much time is spent in each
sleep state.

I assume that you can unload the drivers, but my kernel has USB at this
time. I do plan on building a kernel without USB and see if unloading is
a workable solution. I think it should be.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634