Date: Sat, 5 Dec 2009 12:42:42 -0500 From: Steven Friedrich <freebsd@insightbb.com> To: Kevin Oberman <oberman@es.net> Cc: freebsd-acpi@freebsd.org Subject: Re: ACPI temperature Message-ID: <200912051242.42894.freebsd@insightbb.com> In-Reply-To: <20091205052434.76C4B1CC0B@ptavv.es.net> References: <20091205052434.76C4B1CC0B@ptavv.es.net>
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On Saturday 05 December 2009 12:24:34 am you wrote:
> > 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.
>
I've been running FreeBSD on this laptop since 2005 and only in the past month
has it started shutting down when the temp it 81C. So I found the sysctl where
it reports the temp and I wrote chkCPUTemperature, a bourne script to check
the temp every 10 seconds.
I have placed 1/2 inch spacers, ok, bottle caps from 2 litre bottles, under
the four corners and it's not shutting down now.
I'm an old hardware guy and I understand the die vs package issue, but what's
the temp diff between the two? I was hoping to spark some interest in this
issue with someone who has the ability to verify the actual temp with the
reported temp. I was trying to find a linux user that might be seeing
something different, possibly indicating that FreeBSD's ACPI port has a bug
not in the linux code.
> Also, the maximum die temperature for most modern CPUs is 90C or higher,
> so 52C is not unusual.
The 52C was the temp right after boot. It runs around 72C, but without the
bottle cap spacers it will get to 81C during a make update or port build.
>
> 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.
>
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