acpicpu slowing down computer [was Re: firefox slowness -- X server problem?]

[Thomas Klausner <wiz%netbsd.org@localhost>]

On Wed, Aug 18, 2010 at 07:10:21PM +0200, Jens Rehsack wrote:
> I've read something regarding a select() change on current@. When this was
> introduced first time, my firefox or xchat was unbearably slow, even switching
> between tabs of my gnome-terminal takes up to two seconds.
> When the codes was taken out for analysis, it was fast again, came back,
> slow again. I currently play around with Xen, and subjective feeling,
> running a Xen system is slightly faster than native (except compiling 
> sources).
> Probably it's a hallucination (because the pausing when switching context
> is extremely nerving), but I hadn't time to take a deeper look.

Following your comment, I tried switching kernels, leaving the
userland alone.

Going back to a kernel from 20100702, firefox was fast again.
I looked at the dmesg differences and found that I had enabled acpicpu
in the meantime. I rebuilt a kernel using sources from yesterday, but
disabling acpicpu, and firefox is still fast; with a kernel from
yesterday and acpicpu enabled, it is slow.

So, my original diagnosis was incorrect. It seems to be acpicpu
related, at least for me.

During boot, I always get:
aibs0: warning over limit on 'MB Temperature'
aibs0: warning under limit on 'CHASSIS1 FAN Speed'
aibs0: warning under limit on 'CHASSIS2 FAN Speed'
aibs0: warning under limit on 'CHASSIS3 FAN Speed'
aibs0: warning under limit on 'POWER FAN Speed'
but envstat output right (no acpicpu) now looks ok:

                        Current  CritMax  WarnMax  WarnMin  CritMin Unit
[aibs0]
       Vcore Voltage:     0.936    1.600                      0.800    V
        +3.3 Voltage:     3.216    3.630                      2.970    V
          +5 Voltage:     4.878    5.500                      4.500    V
         +12 Voltage:    12.137   13.800                     10.200    V
     CPU Temperature:    49.000   75.000   60.000                   degC
      MB Temperature:    46.000   75.000   45.000                   degC
       CPU FAN Speed:      1318              7200      600           RPM
  CHASSIS1 FAN Speed:         0              7200      600           RPM
  CHASSIS2 FAN Speed:         0              7200      600           RPM
  CHASSIS3 FAN Speed:         0              7200      600           RPM
     POWER FAN Speed:         0                       7200           RPM
[coretemp0]
    cpu0 temperature:    53.000                                     degC
[coretemp1]
    cpu1 temperature:    51.000                                     degC
[coretemp2]
    cpu2 temperature:    53.000                                     degC
[coretemp3]
    cpu3 temperature:    49.000                                     degC

The CPU is
cpu0: "Intel(R) Xeon(R) CPU           W3520  @ 2.67GHz"
but it's often misregnized by NetBSD with a higher clockrate:
cpu0: Intel Core i7 (Nehalem) (686-class), 3207.40 MHz, id 0x106a5
(both lines from the same cpuctl output).

If someone wants more information, just let me know.
 Thomas