HP6710: acpi_task_0 - WCPU 96.68%

[Roman Pavlik]

This issue appears on 7-CURRENT running on HP 6710b. I'm running
kernel where the following options were commented out:
 #options     PREEMPTION              # Enable kernel thread preemption       
 #options     ADAPTIVE_GIANT          # Giant mutex is adaptive.              

There is issue with the process acpi_task_0. It consumes 96.68% WCPU.

last pid:   951;  load averages:  1.08,  0.81,  0.38    up 0+00:04:18  08:34:12
83 processes:  4 running, 60 sleeping, 19 waiting
CPU states:  0.0% user,  0.0% nice, 46.1% system,  0.5% interrupt, 53.4% idle
Mem: 22M Active, 9036K Inact, 73M Wired, 288K Cache, 15M Buf, 1890M Free
Swap: 4096M Total, 4096M Free

  PID USERNAME    THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
    6 root          1   0    -     0K     8K CPU1   0   3:37 96.68% acpi_task_0
   12 root          1 171 ki31     0K     8K RUN    0   2:18 60.84% idle: cpu0
   11 root          1 171 ki31     0K     8K RUN    1   1:18 34.67% idle: cpu1
  928 root          1  96    0   275M 23532K select 0   0:01  1.76% Xorg
   22 root          1 -52    -     0K     8K WAIT   0   0:05  1.66% irq9: acpi0
   14 root          1 -32    -     0K     8K WAIT   0   0:01  0.00% swi4: clock
   44 root          1 -60    -     0K     8K WAIT   0   0:00  0.00% irq12: psm0
   42 root          1   0    -     0K     8K tzpoll 0   0:00  0.00% acpi_therma
  864 root          1  20    0  5460K  2720K pause  0   0:00  0.00% csh
   27 root          1 -68    -     0K     8K WAIT   0   0:00  0.00% irq17: fwoh
    3 root          1  -8    -     0K     8K -      1   0:00  0.00% g_up
   43 root          1 -60    -     0K     8K WAIT   0   0:00  0.00% irq1: atkbd
  951 root          1  96    0  5524K  3156K select 0   0:00  0.00% ssh
    4 root          1  -8    -     0K     8K -      1   0:00  0.00% g_down
  933 root          1  96    0  6480K  4676K select 1   0:00  0.00% xterm
  936 root          1  96    0  6480K  4580K select 0   0:00  0.00% xterm
  811 root          1  96    0  3256K  1024K select 0   0:00  0.00% moused
  935 root          1  96    0  7136K  4404K select 1   0:00  0.00% xclock
   23 root          1 -80    -     0K     8K WAIT   0   0:00  0.00% irq16: cbb0
  937 root          1  96    0  6480K  4660K select 1   0:00  0.00% xterm
  950 root          1  96    0  3536K  1804K CPU0   0   0:00  0.00% top
  939 root          1  20    0  4472K  2492K pause  0   0:00  0.00% csh
  938 root          1  20    0  4472K  2492K pause  1   0:00  0.00% csh
  856 root          1   8    0  3612K  1584K wait   0   0:00  0.00% login
  940 root          1   5    0  4472K  2464K ttyin  1   0:00  0.00% csh
  934 root          1  96    0  4832K  2800K select 1   0:00  0.00% twm
   38 root          1 -68    -     0K     8K -      0   0:00  0.00% fw0_taskq
   16 root          1 -16    -     0K     8K -      0   0:00  0.00% yarrow
  662 root          1  96    0  3172K  1200K select 1   0:00  0.00% syslogd
    2 root          1  -8    -     0K     8K -      0   0:00  0.00% g_event
    0 root          1  12    0     0K     0K WAIT   0   0:00  0.00% swapper
   53 root          1  12    -     0K     8K -      0   0:00  0.00% schedcpu
    1 root          1   8    0  1888K   476K wait   1   0:00  0.00% init
  909 root          1   8    0  3468K  1472K wait   1   0:00  0.00% sh
   51 root          1  20    -     0K     8K syncer 0   0:00  0.00% syncer
  927 root          1   8    0  4124K  1500K wait   1   0:00  0.00% xinit
  795 root          1   8    0  3200K  1272K nanslp 0   0:00  0.00% cron
  858 root          1   5    0  3172K  1088K ttyin  0   0:00  0.00% getty
  857 root          1   5    0  3172K  1088K ttyin  1   0:00  0.00% getty
  862 root          1   5    0  3172K  1088K ttyin  1   0:00  0.00% getty
    7 root          1   8    -     0K     8K -      0   0:00  0.00% acpi_task_1
  860 root          1   5    0  3172K  1088K ttyin  1   0:00  0.00% getty

I try to run ktrace -p 6, but the ktrace.out is empty. Any suggestion
how to better isolate this bug?

Regards,
--
Roman Pavlík