Re: iMac G5 "windfarm"
Hi Riccardo,
On Wed, Dec 30, 2020 at 9:57 AM Riccardo Mottola
<riccardo.mottola@libero.it> wrote:
>
> Hi,
>
> it is my first time I run linux on an iMac G5 and have some doubts about
> its cooling.
There was a regression at some point, did you check:
* https://lists.debian.org/debian-powerpc/2020/03/msg00035.html
What's your kernel version ?
> I noticed that while installing Debian, the fan spins at full speed and
> it really deserves the term "windfarm", it is as loud as a vacuum cleaner.
>
> Once Linux is fully installed, the system runs quiet when doing nothing
> (console prompt) and remains quiet when doing several things (also
> unexpected ones).
>
> However, e.g. opening GIMP, the fans whir up, just to slow down
> immediately. Then, running a filter is smooth (a bit unexpected).
>
> What I find strange is that fans run shortly full-speed, then stop after
> a second.... or sometimes two!
>
> I have never run MacOS on this system so I can't tell if this is normal
> and if the fan has any intermediate speeds, but this behavior seems strange.
>
> 1) if the CPU is under "slight load" I would expect the fans to
> stabilize to a low speed to keep it cool
>
> 2) if the CPU has high load indeed, then it probably takes more than
> just 1-2 seconds to clear it!
>
>
> in dmesg I see:
>
> [54879.528590] windfarm: Overtemp condition cleared !
> [55034.523862] windfarm: Clamping CPU frequency to minimum !
> [55034.570358] windfarm: Overtemp condition detected !
> [55036.462349] windfarm: CPU frequency unclamped !
> [55036.513668] windfarm: Overtemp condition cleared !
>
> Here it looks that my CPU frequency is temporarily reduced (at the same
> time I hear the fan spinning) and if you see the intervals are very
> short (only one cycle copy-pasted here, dmesg is much longer)
>
>
> Riccardo
>
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