CPU scaling vs Temperature

Phillip Susi psusi at cfl.rr.com
Sun Mar 6 17:10:22 UTC 2011

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On 03/06/2011 11:24 AM, John Moser wrote:
> When my CPU is under extreme load my system shuts down.  Okay, I've
> noted this.  There was a layer of dust caked between the fan and heat
> sink... removed it, that helped.

You've got a hardware problem.  The system should never overheat under
load if the fans are working properly.

> Why not have a user-configurable critical temperature?  'sensors'
> reports my CPU's critical is 95C; but my system shuts down if I maintain
> above 80C long enough.  How about at 75C, CPU frequency scales down to
> minimum?  This seems sensible.  The value can be user-adjustable.

That's up to your bios.

> The Linux kernel doesn't have a scheduler scaler, which would be nice. 
> If the scheduler dedicated X% of CPU time to an infinite loop that runs
> HLT (i.e. the system idle process), then you could say, "Run this CPU
> under 500MHz," and if your CPU scales to 1GHz (mine has 1.9, 1.8, and
> 1.0) and you scaled it to 1.0, the kernel would scale to a jittery 50%
> CPU idle.  This sort of software CPU scaling would probably only find
> use in these sorts of emergency cases.

That is basically what the ACPI throttle interface is.  It absolutely
should not be needed if the frequency is already scaled down, and again,
this is something controlled by the bios.
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