acpi_thermal consuming all CPU

[Brooks Davis]

Some time between ~July 29 and August 15th, something changed that
causes acpi_thermal is get stuck in the ecpoll state when my laptop is
under load.  The basic symptom is that I start a build and after a bit,
system peformance gets lousy (the mouse moves ever few seconds, nothing
updates, etc).  When I managed to get top running on the console, I found
that acpi_thermal was consuming >98% of the CPU and was constantly in
the ecpoll state.  The fans do not run and the system gets very hot (90C).

Booting an old kernel or booting with acpi disabled seems to fix the
problem.

In case it's relevent, prior to Nate's fixes at Usenix, I couldn't
reliably get termperature or power state out of acpi.

The system is an HP Omnibook 500.  I believe I'm running the latest
BIOS.

Here's the sysctl hw.acpi output:
[9:14am] brooks at minya (~): sysctl hw.acpi
hw.acpi.supported_sleep_state: S1 S3 S4 S5 
hw.acpi.power_button_state: S5
hw.acpi.sleep_button_state: S1
hw.acpi.lid_switch_state: NONE
hw.acpi.standby_state: S1
hw.acpi.suspend_state: S3
hw.acpi.sleep_delay: 1
hw.acpi.s4bios: 0
hw.acpi.verbose: 0
hw.acpi.reset_video: 1
hw.acpi.cpu.throttle_max: 8
hw.acpi.cpu.throttle_state: 8
hw.acpi.cpu.cx_supported: C1/0 C2/10
hw.acpi.cpu.cx_lowest: C2
hw.acpi.cpu.cx_usage: 0.01% 99.98%
hw.acpi.thermal.min_runtime: 0
hw.acpi.thermal.polling_rate: 10
hw.acpi.thermal.tz0.temperature: 3202
hw.acpi.thermal.tz0.active: -1
hw.acpi.thermal.tz0.thermal_flags: 0
hw.acpi.thermal.tz0._PSV: 3582
hw.acpi.thermal.tz0._HOT: -1
hw.acpi.thermal.tz0._CRT: 3782
hw.acpi.thermal.tz0._ACx: 3432 -1 -1 -1 -1 -1 -1 -1 -1 -1
hw.acpi.acline: 1
hw.acpi.battery.life: 100
hw.acpi.battery.time: -1
hw.acpi.battery.state: 0
hw.acpi.battery.units: 3
hw.acpi.battery.info_expire: 5

The AML is here:
http://people.freebsd.org/~brooks/debug/brooks-HPOmnibook500.asl

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4
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