Interrupt latency problems

[Richard Todd]

In the freebsd-current mailinglist M. Warner Losh writes:

>Actually, this may be a problem in the acpi code.  I have at least one
>battery that causes my system to 'freeze' for a while.  The mouse
>interrupts aren't lost, per se, but just deferred too long.  That was
>before the latest acpi upgrade, and I've not tried the offending
>battery since then (I think that the zero length messages are related
>to querrying the battery status, but haven't booted windows to find
>out for sure).

I've been seeing similar things on my system for some time, but with the 
ACPI thermal code instead of the battery (which I don't have anyway as it's
a desktop machine :-).  The system every so often freezes for a second or two
and, if you're watching closely with top, you see the CPU usage of the
acpi_thermal process suddenly jump, e.g.,

   23 root       0    0     0K    12K nothin 0  34:44  4.15%  4.15% acpi_therma

Changing how often the acpi_thermal process runs with the 
hw.acpi.thermal.polling_rate sysctl affects how often the freeze happens,
making it clear that it's that part of the ACPI code that's the culprit.
This is on a dual PII/400 system with Tyan Thunder 100GX (S1836DLUAN, IIRC)
motherboard, running -current as of early last week:

FreeBSD ichotolot.servalan.com 5.1-BETA FreeBSD 5.1-BETA #20: Tue May  6 20:14:14 CDT 2003     rmtodd at ichotolot.servalan.com:/usr/src/sys/i386/compile/ICHOTOLOTSMP  i386

I'm not sure if this is before or after the "latest ACPI upgrade" you mention.