There's "powertop" that I use, which shows a listing of things that are
keeping the computer busy.  And it gives recommendations on how to lower
power usage (including setting kernel options, enabling/disabling stuff in
/sys, etc...).  It also estimates power consumption in Watts and gives you
approx time left.

Many recomendations already posted in this emails will be suggested by
powertop.

Simon

On Mon, Apr 2, 2012 at 8:10 AM, Michael Mol <mikemol@gmail.com> wrote:

> On Mon, Apr 2, 2012 at 7:57 AM, Pandu Poluan <pandu@poluan.info> wrote:
> >
> > On Apr 2, 2012 5:00 PM, "Robert David" <robert.david.public@gmail.com>
> > wrote:
> >>
> >> Hi,
> >>
> >> maybe write your hw configuration first. Eg: CPUs, graphic cards, HDDs
> >> (size, speed, type) and others.
> >>
> >> Also provide lspci output and /proc/cpuinfo.
> >>
> >> Then this is a server, maybe with more than one GB nic. If you dont use
> >> spare nics disable them in bios. Do the same with other unneeded stuff.
> >>
> >> If you can access your server and replace cards, remove everything you
> >> dont need. Do not lower fans or dont play with cpu voltage. If you want
> >> to run this server 24/7 it can cause serious problems. It will not save
> >> you much power. Paradoxly this could lead to higher power usage in
> >> some cases, because of hotter devices.
> >>
> >> Remove spare memory cards, if you dont need much memory, etc.
> >>
> >> Robert.
> >>
> >> V Sun, 01 Apr 2012 17:04:58 +0200
> >> Jarry <mr.jarry@gmail.com> napsáno:
> >>
> >> > Hi,
> >> >
> >> > admin of a colo-center keeps complaining my server is going
> >> > a little over power-limit (which they have set as ~120W per
> >> > 24h/avg, while my server needs ~130-135W). So I need to find
> >> > a way to save at least those 15W, or I will be moved to
> >> > higher tarif (which means higher costs for server-housing).
> >> >
> >> > Before going hard(ware) way, I would like to try first
> >> > all possible software solutions. What I tried up to now is
> >> > cpufreqd, CONFIG_NO_HZ=y, and spindown. In addition to that
> >> > I adjusted fan-speeds to a little lower values and turned
> >> > off some unneeded peripherials (in bios).
> >> >
> >> > Is there anything else I could do? Any tips would be greatly
> >> > welcomed...
> >> >
> >> > Jarry
> >> >
> >>
> >>
> >
> > I'd rather have *more* RAM than causing unnecessary swaps.
> >
> > Try using a smaller swapfile to reduce swap tendencies. You can always
> push
> > a larger swapfile into service when needed.
> >
> > There's also a kernel knob to set 'swappiness', but I forget what
> exactly.
> > Try 'sysctl -a | grep swap'
>
> Swappiness is the knob you want to set if you want to reduce
> swappiness. I set mine to 0; swap only when absolutely necessary.
>
> In /etc/sysctl.conf:
> vm.swappiness = 0
>
> On the command line:
> sysctl -w vm.swappiness=0
>
> --
> :wq
>
>