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From: pradeep hettiarachchi <pradeepmh@wayne.edu>
Date: Mon, 20 Jun 2011 22:15:47 -0400
Message-ID: <BANLkTimHRRJ0g6VejfR8o-a5i42Puag0XQ@mail.gmail.com>
Subject: CPU Instantaneous Power Consumption
To: linux-kernel@vger.kernel.org, arjan@infradead.org
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Hi,

I am a PhD student and doing a research which involves
control-theoretic real-time process/job scheduling. Here is my
question:

I need to calculate the power consumption of a single or two CPU cores
and equivalent Thermal Dissipation accurately. I did not find any
supporting material from Intel to find the instantaneous power
consumption (and thermal dissipation) of the CPU. Therefore I am
trying some alternative path; I measure the CPU regulator input
current (using a very small shunt resister in series with 4 pin CPU
ATX connector). Also, assuming that the CPU voltage regulator operates
at 12 V rated, I could calculate the input power to the CPU regulator.

However without knowing the following I cannot complete my power calculation:

1) What is the DC-to-DC CPU regulator efficiency ?
2) What is the relationship between TDP and input power to the CPU ?
3) Do you suggest any other better method to calculate the
instantaneous input power to the CPU ?
 (I can think of calculating accurate instantaneous CPU power as VID
(corresponding Vcc) x CPU_current_from_regulator; but, how do I read
instantaneous VID ? Is there any MSR that I can instantly access to
read VID ? (I think Intel has hidden theses details from system
developer) )

Please help me to find answers to these questions.


Sincerely,

Pradeep M. Hettiarachchi
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