Its been a while since I needed to be mobile with FreeBSD again. I remembered that there’s several out of the box tuning things that you should do in /etc/rc.conf and a few modules you should load for your mobile workstation.
/etc/rc.conf: powerd_enable="YES" economy_cx_lowest="LOW" economy_cpu_freq="LOW"
These will slow your laptop down when running of battery and should give you the needed juice to take notes and update your remote projects. I wouldn’t recommend them for a machine you need to do buildworlds upon. 🙂
This one is a module that I forgot about for some time. If you load it, you’ll get a couple of new tunables that can be used to turn down the backlight, which is useful even if all you want is to not disturb your better-half when you are reading at night.
sysctl hw.acpi.video hw.acpi.video.lcd0.economy: 50 hw.acpi.video.lcd0.fullpower: 80
You can throw these into your /etc/sysctl.conf at whatever value you like. See the man page, man 4 acpi_video for more information.
% acpiconf -i0|less Design capacity: 3900 mAh Last full capacity: 3827 mAh Technology: secondary (rechargeable) Design voltage: 11100 mV Capacity (warn): 390 mAh Capacity (low): 118 mAh Low/warn granularity: 39 mAh Warn/full granularity: 39 mAh Model number: DELL 9C26T33 Serial number: 48476 Type: LION OEM info: SMP State: discharging Remaining capacity: 52% Remaining time: 3:07 Present rate: 640 mA (6935 mW) Present voltage: 10837 mV
Not too shabby for power savings. Not sure if .6 Amp is really enough to make this solid. I think this gives me a solid 4 hours of note taking and walking around.