linux-kernel - Re: [linux-pm] Power Management framework proposal

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Date:	Mon, 23 Jul 2007 10:56:36 +0200
From:	Ondrej Zajicek <santiago@...reenet.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	david@...g.hm, Igor Stoppa <igor.stoppa@...ia.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-pm <linux-pm@...ts.linux-foundation.org>
Subject: Re: [linux-pm] Power Management framework proposal

On Sun, Jul 22, 2007 at 09:19:17PM -0700, Arjan van de Ven wrote:
> let me give you a real world example then, and the numbers I'm using are
> ballpark the same as you'll find in a (mobile) core 2 duo datasheet, I
> just rounded them a little so that the math works out nice.
> 
> power at full speed: 34W
> power at half speed: 24W
> power at idle: 1W

I have usually seen different numbers, for example:

http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/30430.pdf

Although this paper speaks about thermal design power instead of power
consumption, i suppose that it should be roughly equal.

For example Athlon 64 3700 (ADA3700AEP5AR):

2.4 GHz, 1.5 V -> 89 W
2.2 GHz, 1.4 V -> 72 W
2.0 GHz, 1.3 V -> 53 W
1.8 GHz, 1.2 V -> 39 W
1.0 GHz, 1.1 V -> 22 W


Even my measurement on PC (Athlon X2, VIA K8T890) of complete PC power
consumption shows that it is more efficient to be busy for 2 time units
on 1 GHz than be busy for 1 time unit and be idle for 1 time unit
on 2 GHz.

1 GHz:
both cores idle:	48 W
one core busy:		57 W
two cores busy:		66 W

2 GHz:
both cores idle:	54 W
one core busy:		78 W
two cores busy:		95 W

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago@...reenet.org, jabber: santiago@....netlab.cz)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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