Date: Tue, 27 Jan 2009 17:39:39 -0800 From: Chuck Swiger <cswiger@mac.com> To: Shawn Badger <shawnbadger@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Laptop battery life on FreeBSD Message-ID: <BAA6EEC3-FF5A-4636-A63E-32B7ECB4C48A@mac.com> In-Reply-To: <497FAB99.1050607@gmail.com> References: <497F9683.3080905@gmail.com> <2F8A37C3-178D-48CB-A17A-CBF6CAD86F60@mac.com> <497FAB99.1050607@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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.... > 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. :-)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?BAA6EEC3-FF5A-4636-A63E-32B7ECB4C48A>