TM1/TM2

TM1/TM2

[Erik Slagter]

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Hi,

Is there a reliable way to know whether tm1/tm2 and/or other throttling
have been applied by the hardware?

I am very suspicious that my cpu does tm1 or tm2 once in a while, but I
can't prove it. It doesn't seem to be reported via MCE, which I'd expect.

FWIW I have a Pentium D915 and it has eist and tm1/tm2 (although linux
says only tm1), all enabled in the BIOS.

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Re: TM1/TM2

[Dave Jones]

On Mon, Oct 02, 2006 at 01:30:20PM +0200, Erik Slagter wrote:
 > Hi,
 > 
 > Is there a reliable way to know whether tm1/tm2 and/or other throttling
 > have been applied by the hardware?
 > 
 > I am very suspicious that my cpu does tm1 or tm2 once in a while, but I
 > can't prove it. It doesn't seem to be reported via MCE, which I'd expect.
 > 
 > FWIW I have a Pentium D915 and it has eist and tm1/tm2 (although linux
 > says only tm1), all enabled in the BIOS.

Thermal monitoring isn't actually handled by cpufreq, but by the mcheck code
(arch/i386/kernel/cpu/mcheck/p4.c)

It appears that if it is in use it does the following printk's..

    printk(KERN_EMERG "CPU%d: Temperature above threshold\n", cpu);
    printk(KERN_EMERG "CPU%d: Running in modulated clock mode\n",

So if you haven't seen those, it isn't in effect.

The only other thermal throttling is that provided by the p4-clockmod
module, which will scale regardless of temperature. If you don't want
it to scale, don't load the module ;)

	Dave

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