Linux Power Saving

Hello all,

Is any any tools out there that help Linux saves the powers.

Consider the "Run mode": It will save energy if we can control
the Linux system so that it use only the amount of resource (CPU, RAM,
disk IO, network IO)
that it needs to.

Usually, Linux doesn't need to run on its 100% horse power.
It is true for both servers and PCs.

Ideas: Power Management in Linux-Based Systems


Nguyen Vu Hung

From: Huan Truong

Things that can be put into consideration:

- Spin down the hard drives after, say, 10 minutes idling. hdparm can do this.

- Undervolt your CPU, have a look at www.linux-phc.org, it isn't
terribly hard. Your CPU will run cooler.

- Undervolt your RAM and such (in your BIOS/uEFI setting)

- Plug your USB powered devices (USB mice and flash drives and dongles
and such) to your monitor's USB hub. When you turn off the monitor,
you turn them all off -- however this largely depends on how your
monitor manufacturer implements the USB hub on the monitor. Mine (Dell
2209WA) the hub turns off when the monitor goes to standby, which is
set to 10 minutes after I leave my desk.

- AC97 chips has a low-power mode, but normally isn't turned on by
default, try compiling a kernel with AC97 powersave mode timeout = 2
secs for example.

- Of course powertop will have some very good advices. Put them in rc.local.

- Buy CPUs with high power efficiency because not all CPUs are made
equal. Buy ones with low TDPs. For example, the SU line of Intel
mobile processors consumes only 10W and the T line of the intel I*2
desktop processor consumes only half what a non-T one consumes... I'm
having this one for my desktop
http://ark.intel.com/Product.aspx?id=53423 -- it consumes 35W under
load -- notice that a normal i3 CPU consumes 65W under load.

- If you don't gaem, use Intel graphics, don't use a fancy NVidia
card. Less headache too.

- I don't believe that using XFCE or xmonad or (insert your favorite
DE here) will save power, unless someone can prove me the otherwise.

- Turn on wake-on-LAN and let your computer sleep when idle, only wake
it up when needed.

- I've heard that USB HID devices uses pooling and PS2 uses
interrupts. If that's true, logically it isn't a terribly good idea to
plug your mouse and/or kb into USB ports as when you use USB the CPU
has to wake up a hundreds of times sampling the mouse and keyboard
input even when your devices are idle. I'm unsure about this, take it
with a grain of salt.

- Lastly if you're desperate to see how little power can you get, use
ARM http://www.pandaboard.org/ -- the whole thing consumes somewhere
like 8W under load. If you're *really* desperate, then, investigate
and invest your money into microcontrollers:
-- If you dive into it, this micro runs at 16Mhz for something like
two miliamps and trust me there are plenty of room for improvements...
What can you do with it is another problem, but definitely your mad
skillz in C are not gonna be wasted. Heck, my watch has been running
for months: http://hackaday.com/2011/02/27/google-two-factor-authentication-in-a-wristwatch/

Good luck..................


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