Re: Laptop getting hot

[YONETANI Tomokazu <qhwt+dragonfly-kernel@xxxxxxxxxx>]

On Tue, Dec 23, 2003 at 12:27:11AM +0900, YONETANI Tomokazu wrote:
> On Sat, Nov 29, 2003 at 07:55:38PM +0000, Johannes Hofmann wrote:
> > I just installed DragonFlyBSD on my Laptop (Thinkpad i1200). Everything
> > works great, but it is getting considerably hotter than with FreeBSD.
> > I tried against recent -current and 4.3-stable (because I just had a 4.3 CD).
> > I had neither apm nor acpi enabled and the fan did not turn on 
> > at all. With DFBSD it start almost immediately, even without any load.
> > Do you have any idea, what could be causing this?
> 
> Same thing happens to me with Dell Optiplex G240(a Desktop, though).
> When it's running FreeBSD-stable, the cooling fan is very calm, while with
> DragonFly the fan keeps turning noisily as if it's running buildworld.
> I haven't tried recent acpi code from FreeBSD-CURRENT, but it doesn't seem
> to have any CPU throttling feature.

I found that DragonFly box produces less heat when it's playing
some music with mpg321 from ports.

I did the following experiment with my Dynabook:

In one terminal[A], display the temperature every 10 seconds.
# sysctl hw.acpi.thermal.polling_rate=10
hw.acpi.thermal.polling_rate: 30 -> 10
# while :; do sysctl hw.acpi.thermal.tz0.temperature; sleep 10; done
hw.acpi.thermal.tz0.temperature: 3382
hw.acpi.thermal.tz0.temperature: 3382
hw.acpi.thermal.tz0.temperature: 3382

In another terminal[B], play some .mp3 file.
$ mpg321 foo.mp3

Look at terminal [A], the temperature goes down and the cooling fan
slows down. The temperature slowing rises again after a minute or so.
hw.acpi.thermal.tz0.temperature: 3382
hw.acpi.thermal.tz0.temperature: 3382
hw.acpi.thermal.tz0.temperature: 3362
hw.acpi.thermal.tz0.temperature: 3262
hw.acpi.thermal.tz0.temperature: 3262
hw.acpi.thermal.tz0.temperature: 3262
hw.acpi.thermal.tz0.temperature: 3212

Press ctrl+C in terminal[B] to stop mpg321, and the temperature goes up
immediately.
hw.acpi.thermal.tz0.temperature: 3262
hw.acpi.thermal.tz0.temperature: 3262
hw.acpi.thermal.tz0.temperature: 3312
hw.acpi.thermal.tz0.temperature: 3312
hw.acpi.thermal.tz0.temperature: 3352

If I do the same thing with mplayer(even with -quiet option),
the temperature almost doesn't change and the fan keeps running
noisily. 'top -I' shows that mpg321 is almost always in 'pcmwr' state,
while mplayer is spending time mostly in 'poll' state.

So, it seems to me that either it has something to do with how
idlethread spends CPU cycles, or Fred can't sleep well without music.