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Date:      Thu, 10 Sep 2009 12:18:03 +0930
From:      "Daniel O'Connor" <doconnor@gsoft.com.au>
To:        Alexander Motin <mav@freebsd.org>
Cc:        FreeBSD Stable <freebsd-stable@freebsd.org>, Robert Noland <rnoland@freebsd.org>
Subject:   Re: Detecting CPU throttling on over temperature
Message-ID:  <200909101218.05070.doconnor@gsoft.com.au>
In-Reply-To: <4AA7AA9B.9010709@FreeBSD.org>
References:  <1252426982.00160755.1252414203@10.7.7.3> <1252501703.85394.3473.camel@balrog.2hip.net> <4AA7AA9B.9010709@FreeBSD.org>

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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=20
branding (I don't know if it really IS one or not).

On the bench here I could not observe an effect by running=20
dd if=3D/dev/zero bs=3D128k count=3D5000| 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=20
quite odd..

Still, now I have been reminded of coretemp I can monitor it=20
on "suspect" systems :)

=2D-=20
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

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