Laptop battery life on FreeBSD
shawnbadger at gmail.com
Tue Jan 27 20:41:19 PST 2009
Chuck Swiger wrote:
> On Jan 27, 2009, at 4:49 PM, Shawn Badger wrote:
>>> Have you tried reducing HZ to 100 (put kern.hz="100" in
>>> /boot/loader.conf and reboot)?
>>> Are you running powerd? Look into "sysctl hw.acpi" and "sysctl
>> Thanks for the ideas Chuck. I lowered kern.hz to 100 as you
>> suggested (does this affect the kernel's ability to track time in
>> milliseconds? ie. if I want to run a benchmark using the 'time'
> Changing the scheduler quantum won't affect the system clock or the
> ability to do millisecond-level timing of userland processes. It does
> affect the granularity of things like ipfw/dummynet if polling is
> enabled, but shouldn't have any real negative effects otherwise.
> For most of Unix history, HZ=100 was a common default, and the reduced
> context switch frequency should result in a decent improvement to
> power drain. If you have a concern, consider comparing against HZ=250
> and see how the battery life and responsiveness or granularity of
> network traffic, etc feel....
Thanks for the info. I'll definitely do some tests and find a good
>> And the output of the two sysctl queries is posted here:
>> I'm not very familiar with acpi, so if you see anything that could be
>> optimized, I'd appreciate the feedback.
> I have limited experience with running FreeBSD on a laptop personally
> , so others will likely have more relevant feedback; I'm just aware
> of some starting points. :-)
> Regards, --
> : I've helped a few people run FreeBSD 5.x/6.x on various IBM
> ThinkPads (circa T.42s) an maybe an HP Pavillion or Dell Latitude, and
> I've run FreeBSD a bit on a Mac mini and a MacBookPro (2,2), but I
> don't use FreeBSD on a laptop regularly...I think of it as a server
> OS. :-)
I too generally think of FreeBSD as a server OS, but I just can't get
over how nice the development environment is - hence the laptop.
More information about the freebsd-questions