Annoyances with passive thermal code (acpi_thermal)

[Kevin Oberman]

I've noted an unpleasant mis-behavior in acpi_thermal.

1. Killed powerd
2. Set dev.cpu.0.freq to 1200 (I was on batteries and wanted to stretch
   them) 
3. Started a BIG build...openoffice

The temp went up over _PSV and the CPU was slowed to 1050. The CPU
cooled for a while and the freq was reset to 1800 which started draining
my battery way too fast.

Ideally, acpi_thermal should store the frequency when it cuts speed and
restore that speed when the CPU cools, not the maximum speed.

Not a huge problem as I caught it before my battery was too badly
impacted, but it would have been really annoying if I had had the
battery die before I noticed. Since I run with write cache on my disks,
this could have been a disaster with all of the file activity the build
of openoffice was generating. (OK. Building openoffice under these
circumstances my be a bad idea, but it takes many hours to build and I
try to get it built when I can.)
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634