Detecting CPU throttling on over temperature

[Daniel O'Connor]

On Wed, 9 Sep 2009, Alexander Motin wrote:
> > around 100C.  I did pull the c2d cpu docs at one point trying to
> > look at cpufreq.  If you are bored, you can grab the docs from
> > intel and double check.
>
> AFAIR C2D supports three protection technologies. When CPU is hot, it
> starts reducing frequency (multiplier) and voltage, alike to IEST. If
> it is insufficient, it starts to skip core cycles, alike to TCC. If
> it is still insufficient and temperature rises above about 100C,
> emergency shutdown happens.

Hmm, I have since realised it's an E2140 which doesn't have Core2Duo 
branding (I don't know if it really IS one or not).

On the bench here I could not observe an effect by running 
dd if=/dev/zero bs=128k count=5000| md5
in a loop and checking the frequency with
dev.cpu.0.freq

However the idle time seemed to go up, but only to 10% or so, it was 
quite odd..

Still, now I have been reminded of coretemp I can monitor it 
on "suspect" systems :)

-- 
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 188 bytes
Desc: This is a digitally signed message part.
Url : http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20090910/53cc230b/attachment.pgp