linux-kernel - Re: PROBLEM: Celeron Core

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Message-ID: <20080120191643.GB28190@one.firstfloor.org>
Date:	Sun, 20 Jan 2008 20:16:43 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Robert Hancock <hancockr@...w.ca>
Cc:	David Newall <davidn@...idnewall.com>,
	Andi Kleen <andi@...stfloor.org>,
	Matt Mackall <mpm@...enic.com>,
	Chodorenko Michail <misha@....by>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: PROBLEM: Celeron Core

> I believe that all throttling does is forcibly halt the CPU on a 
> particular duty cycle. This will reduce the rate of power consumption, 
> but reduces the CPU performance by a greater amount (since even at 100% 
> halted the CPU still consumes power) and so actually reduces performance 
> per watt. It will spread the heat and power usage produced from a given 
> workload task out in time (thus its usefulness in limiting CPU 
> temperature) but will consume more power overall.

...and  more importantly deep sleep states in idle save far more power than
anything else and with throttling the CPU is idle shorter.

-Andi
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