Re: Laptop getting hot

[Johannes Hofmann <Johannes.Hofmann@xxxxxx>]

This is strange, but similar to my experience: 
I compiled a kernel module, that only called "hlt" in a loop for some while. 
It turned out, that the processor got even hotter by this!


YONETANI Tomokazu <qhwt+dragonfly-kernel@xxxxxxxxxx> wrote:
> 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.