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Date:      Thu, 14 May 2015 10:33:23 -0400
From:      mfv <mfv@bway.net>
To:        "William A. Mahaffey III" <wam@hiwaay.net>
Cc:        "FreeBSD Questions !!!!" <freebsd-questions@freebsd.org>
Subject:   Re: sysctl question
Message-ID:  <20150514103323.044eb426@gecko4>
In-Reply-To: <5554AB4B.7070908@hiwaay.net>
References:  <55541052.6020802@hiwaay.net> <20150514055826.01e841ae@gecko4> <5554AB4B.7070908@hiwaay.net>

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On Thu, 14 May 2015 09:10:10 -0453
"William A. Mahaffey III" <wam@hiwaay.net> wrote:

> On 05/14/15 05:04, mfv wrote:
> > Hello William,
> >
> > I had the same problem using amdtemp but used the sysctl setting
> > "dev.amdtemp.%d.sensor_offset" to make it more accurate. The value
> > was determined by comparing the unadjusted value of admtemp with
> > the value shown in the BIOS.  In my case the setting
> > in /etc/sysctl.conf is:
> >
> >   dev.amdtemp.0.sensor_offset=24
> >
> > A room thermometer was also helpful to measure the difference by
> > comparing the difference between the room temperature and the BIOS
> > after the CPU was placed under load.
> >
> > To read the value I then bound the F2-key in csh.cshrc file as
> > follows:
> >
> >    bindkey -c "^[OQ" 'sysctl -e dev.amdtemp.0.core0'
> >
> > The results of the reading are not as accurate as I would like but
> > are an improvement.
> >
> >      Cheers ...                                 __o
> >                                               _ \<,_
> >      Marek                                   (+)/ (+)
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > On Wed, 13 May 2015 22:08:57 -0453
> 
> Interesting. How did you determine BIOS temp, quickly reboot & read
> it ? I thought sysctl or something similar could basically read the
> BIOS & either use it directly or translate it ....
> 

Hello William,

Sorry about my previous top-posting.  It was early in the AM and I was
not properly caffeinated.

The short answer to your question is yes.  I used a couple of memory
testing programs to maximize the load on the CPU and then rebooted and
quickly noticed the temperature as given by the BIOS.  I have an ASUS
motherboard where the BIOS provides a number of temperatures.  I
noticed the CPU value and subtracted the ambient temperature as shown
by a simple room thermometer and used the difference for the amdtemp
offset. As mentioned before it is not as accurate as I would like, but
an offset of 24 degrees is a significant improvement.

I do not know why there is such a large difference but at least the
offset provides the opportunity to reduce the gap.

Cheers ...

Marek



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