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. 🙂

/boot/loader.conf
acpi_video_load="YES"

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.