[patch] enhance powerd(8) to handle max temperature

[Hajimu UMEMOTO]

Hi,

>>>>> On Fri, 27 Jul 2007 16:43:29 +0200
>>>>> Pietro Cerutti <gahr at gahr.ch> said:

gahr> Hi list,
gahr> here is a patch to allow powerd(8) accept a "-t tval" option to set a
gahr> temperature limit above which performance should be decreased.
gahr> It's a first draft, and I identified the following problems:

gahr> - the CPU temperature takes some time to decrease, so powerd keeps
gahr> decreasing the CPU frequency until the temperature is below the limit.
gahr> The effect is a "increase to maximum, decrease to minimum, increase to
gahr> maximum, decrease to minimum, ...." which may not be desirable.

gahr> - the temperature is retrieved by the hw.acpi.thermal.tz0.temperature
gahr> sysctl MIB. Support for other methods would be desirable.

gahr> The patches to powerd.c and powerd.8 are here:
gahr> http://www.gahr.ch/FreeBSD/patches/powerd.c.diff
gahr> http://www.gahr.ch/FreeBSD/patches/powerd.8.diff

gahr> Any comment is welcome!

We have a passive cooling mechanism already in our kernel.  It runs
according to an ACPI specification.

Sincerely,

--
Hajimu UMEMOTO @ Internet Mutual Aid Society Yokohama, Japan
ume at mahoroba.org  ume@{,jp.}FreeBSD.org
http://www.imasy.org/~ume/