Date: Fri, 04 Dec 2009 21:24:34 -0800 From: "Kevin Oberman" <oberman@es.net> To: Steven Friedrich <freebsd@insightbb.com> Cc: freebsd-acpi@freebsd.org Subject: Re: ACPI temperature Message-ID: <20091205052434.76C4B1CC0B@ptavv.es.net> In-Reply-To: Your message of "Fri, 04 Dec 2009 23:37:04 EST." <200912042337.04403.freebsd@insightbb.com>
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> From: Steven Friedrich <freebsd@insightbb.com>
> Date: Fri, 4 Dec 2009 23:37:04 -0500
> Sender: owner-freebsd-acpi@freebsd.org
>
> I sent this to questions last Sunday, but only one person responded. He's
> running FreeBSD 8 and I think his system is reporting bogus temps too.
> I think there might be a missing scaling factor. I'm a hardware guy, but I
> don't currently have temperature measuring equipment and I would want to do it
> on one of my towers (which are currently in storage), not my laptop anyway.
>
> I booted my HP Pavilion zd8215us and I immediately invoked chkCPUTemperature.
> The first temp reported was 52C, which is 125.6F. This leads me to believe
> that acpi has an anomaly regarding temperature measurement. The ambient temp
> was 71F (21.6C). The machine had been off for over eight hours.
>
> Here's chkCPUTemperature:
>
> #!/bin/sh
> # $Id:$
> #
>
> # CPU Temperature Information from ACPI
> POLLING_RATE=`sysctl hw.acpi.thermal.polling_rate|awk '{print $2}'`
> while [ 1 ]
> do
> sysctl hw.acpi.thermal.tz0.temperature
> sleep $POLLING_RATE
> done
>
> uname -a
> FreeBSD laptop2.StevenFriedrich.org 7.2-RELEASE-p4 FreeBSD 7.2-RELEASE-p4 #1:
Why do you not believe the report? The temperature reported is usually
measured on the die, not the package. (You couldn't measure it externally,
if you wanted to.) Due to the VERY low thermal mass of the die, it heats
up very quickly.
Also, the maximum die temperature for most modern CPUs is 90C or higher,
so 52C is not unusual.
The reading of the temperature is pretty trivial, although the the units
(degrees K) does require a the substraction of a constant. I really
suspect that the die IS at 52C by the time the system has been running
for even a minute.
--
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
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