[Sorry if this gets through twice: I messed up last time...]

Hi,

I have moved a whole bunch of servers off a rack of Solaris machines  
and onto a single Linux laptop which I am trying to run on low-enough  
power to run off solar PV for as much of the time as possible (see  
http://www.earth.org.uk/low-power-laptop.html) and total power use  
has come down from ~670W to <30W on mains (<20W powered from solar PV  
via an efficient DC/DC converter).

But I'm not sure how far further I can push the h/w I have.

For example, it doesn't show C3 or C4 states available which is a  
shame since it is 99% idle (most time is spent in C2).

Also, it doesn't show HPET as being available, which results in ~50  
extra wakeups per second.

Now I *am* running a bunch of DNS, NTP, SMTP, and HTTP servers on  
that (Core Duo T2250) machine, albeit quiet ones, that generate ~30+  
wakeups per second themselves legitimately.

Is it worth trying to force activate HPET, C3 ad C4?

How can I safely do it if so?  I have looked at the BIOS with  
dmidecode and biosdecode, and don't get any great clues.

I have played with building a previous kernel but am now simply  
running a stock (22-rc7) Ubuntu "Gutsy" kernel in my "Feisty" system.

I am using cpufreqd/ondemand which I have tuned as good as I can get  
(quick builds, idles in lowest freq ~99%).

I am using laptop-mode.

And of course I have used powertop to help tune userspace and  
cpufreqd, which is why I am here!

Rgds

Damon


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