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
debug.cpufreq"....
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'
utility?).
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
balance.
And the output of the two sysctl queries is posted here:
http://pastebin.com/m5ae8aa1c
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
[1], so others will likely have more relevant feedback; I'm just aware
of some starting points. :-)
Regards, --
-Chuck
[1]: 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.
Shawn
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