Throttling the CPU to reduce fan noise
On netbsd-users, Cem Kayali has
posted a script to adjust the CPU frequency according to the system temperature,
and thus reduce fan noise. This is different from pkgsrc's estd,
which just adjusts the CPU speed according to the system load, so
it's quite the contrary. Cem uses the envstat(4) framework to
determine CPU temperature, and then slows the CPU down with sysctl(1).
An alternative approach was
suggested by Jeremy Reed,
which hints at the powerd(8) script hooks that can be set to
act on corresponting ACPI Thermal Zone (acpitz) events.
Jeremy Reed's blog posting
for a few more ideas, plus a hint that this may become
documented even better in the future.
While there: At his website,
Jeremy has a number of open questions
around NetBSD, and I guess answering them would be good
for mankind. Any takers?
[Tags: acpi, cpu, fan]