Saving power by disabling sound chip on Linux
For years I have been running Linux servers. Some time ago I built a NAS box running Ubuntu Server. I’ve done quite some tweaks to reduce power consumption. But there must be more. Or less, so to speak.
First, you need to see what’s using power, and control it:
apt-get install powertop cpufrequtils laptop-mode-tools
Especially powertop is great. First, run “sudo powertop –calibrate” for it to gather statistics for your system (this may take a while). Then just run “sudo powertop” and browse around.
In the ‘overview’ section on my NAS it said the Realtek device was busy 100%. Which makes no sense, as I am using this box as a NAS so it could have done without audio chip altogether.
Next, have a look at your modules:
There I noticed a lot of modules related to the sound subsystem, i.e. the Realtek chip in my ATOM board. There’s no need to load all these modules. Also, the bluetooth module is loaded, but not used.
Luckily, there is a simple way to disable the bluetooth and sound system, by blacklisting these kernel modules. To do this, edit /etc/modprobe.d/blacklist.conf.
I added the following lines, these modules all showed up in lsmod:
(note to take care not to blacklist any modules you actually need!)
After a reboot they do no longer show up in lsmod.
There may also be other modules which can be unloaded. I’m thinking of ‘lp’ (printer), ‘parport’ and ‘video’.
Of course all this is only worth something if we can quantify the savings. This is still a TODO.