[ltp] Noisy fan on T42

[Alexandru D. Salcianu]

Hello!

I checked the CPU speed by looking into /proc/cpuinfo (I will try your
method too).  As expected, the CPU speed stays at 600Mhz most of the
time, and goes up only when I do something serious.  I don't think the
CPU frequency or the CPU temperature is the issue: as indicated by
ibm_acpi, the CPU temperature (the first of the 8 reported
temperatures) is quite small: 40-42C

I think one of the following situations takes place:

1) the temperature indications from ibm_acpi are incorrect;

2) there is some other source of heat (unlikely: I've tried laptop
   mode to decrease the heat generated by the HDD; I've even booted
   the system in text mode to avoid the GPU generated heat; also, when
   I ran X, the radeon driver has the dynamic frequency scaling
   enabled);

3) somehow, linux doesn't realize that the temperature is low and it
   should stop the fan (once the fan goes full power - pretty soon
   after booting - it *never* comes back to a slow speed, and it
   definitely never stops)

Best,

Alex

> > It looks to me that current power management tools in Linux simply
> > cannot handle my laptop (the fan noise is acceptable in Windows,
> > although things can be improved a bit there too).  I'm looking forward
> > to trying the next versions of acpi and ibm_acpi.
> Have you verified that your processor is not running at full speed by
> loading the speedstep_centrinom module and looking in
> /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq ?  I'm not sure the
> BIOS settings work in Linux, my fan was running almost all the time but once
> I loaded speedstep_centrino and cpufreq_ondemand and ran this:
> 
> ---===
> #!/bin/sh
> 
> DIR=/sys/devices/system/cpu/cpu0/cpufreq
> 
> echo -n Enabling on-demand CPU frequency governor...
> echo ondemand > $DIR/scaling_governor
> cat $DIR/cpuinfo_min_freq > $DIR/scaling_min_freq
> cat $DIR/cpuinfo_max_freq > $DIR/scaling_max_freq
> echo done
> ===---
> 
> the fan only comes on occasionally now and is quieter when it does come on.
> 
> --