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Re: Thermal scheduling
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Re: Thermal scheduling


  • Subject: Re: Thermal scheduling
  • From: Sam Hart <email@hidden>
  • Date: Wed, 29 Sep 2004 13:45:43 +0100


John wrote:

Does the Darwin 7.4 (or later) kernel scheduler take CPU temperature into
account at all?

In the scheduler ? I doubt it

I've been poring over the xnu source trying to find a place
where CPU temp is involved in some sort of thread priority or scheduling
calculation, but have not found one yet. I'm hoping it'll be faster to just
ask here :)

What are you trying to achieve ?

The temperature of the CPU(s) is not gleaned by reading a register, at least not on PowerPC.

You would set ( in supervisor mode ) a threshold watchpoint, and when the threshold is breached an interrupt is generated.

It is CPU model dependent, in fact it might even be optional for PowerPC.

Different strategies can be employed to cool down the CPU(s), spinning up a fan isn't a bad one :)

How temperature shifts are handled by Apple could well be considered a competitive advantage.

This is no word of authority but my guess would be that it is handled by AppleThermal.kext
which appears to be closed source.



S a m

-------------------------------------------------------

Drawing on my fine command of language, I said nothing.

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