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From: Andi Kleen <andi@firstfloor.org>
To: Matt Mackall <mpm@selenic.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	Chodorenko Michail <misha@one.by>,
	linux-kernel@vger.kernel.org
Subject: Re: PROBLEM: Celeron Core
Date: Sat, 19 Jan 2008 05:27:50 +0100	[thread overview]
Message-ID: <20080119042750.GA24481@one.firstfloor.org> (raw)
In-Reply-To: <1200715842.25782.95.camel@cinder.waste.org>

> So while throttling may be less efficient in terms of watt seconds used
> to compile something than running at full speed, it is incorrect to say
> it uses less power. One machine running for an hour throttled to 50%
> uses less power (and therefore less battery and cooling) than another
> running at full speed for that same hour.

Not for the same unit of work. If you just run endless loops you 
might be true, but most systems don't do that. 

In terms of laptops (or rather in most other systems too) you usually care 
about battery life time while the system is mostly idling (waiting
for your key strokes etc.). In this case enabling throttling
as a cpufreq driver will not make your battery last longer.

Also skipping the clocks does not actually safe all very much power
compared to the other measures C-states or speedstep do (like dropping voltage) 

This means enabling it will likely make your laptop battery last shorter.

-Andi

  reply	other threads:[~2008-01-19  4:24 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-18 19:06 PROBLEM: Celeron Core Chodorenko Michail
2008-01-18 21:11 ` Andi Kleen
2008-01-19  0:27   ` Matt Mackall
2008-01-19  1:15     ` Andi Kleen
2008-01-19  4:10       ` Matt Mackall
2008-01-19  4:27         ` Andi Kleen [this message]
2008-01-19  4:40           ` Matt Mackall
2008-01-19  4:54             ` Andi Kleen
2008-01-20  4:35               ` David Newall
2008-01-20  5:13                 ` Andi Kleen
2008-01-20  5:23                   ` David Newall
2008-01-20  5:42                     ` Andi Kleen
2008-01-20 20:53                     ` Lennart Sorensen
2008-01-20 11:18           ` Geert Uytterhoeven
     [not found] <fa.2Y+LplM9PCtpiAXzv/aJ3Pcnv4Y@ifi.uio.no>
     [not found] ` <fa.OpXJDCw416yeXEvt0cwrupi/qS0@ifi.uio.no>
     [not found]   ` <fa.sj34KNXkf9z/ZO3fVJ+CYcgcuCs@ifi.uio.no>
     [not found]     ` <fa.qpK4b5H7lkLeIaPtbJKzKV46yFY@ifi.uio.no>
     [not found]       ` <fa.WeBRuL3UPPVPESVzfopvVyNcAw4@ifi.uio.no>
     [not found]         ` <fa.LZLUxfR64dAZFPtin9JNet7ieiY@ifi.uio.no>
2008-01-20 18:24           ` Robert Hancock
2008-01-20 19:14             ` Matt Mackall
2008-01-20 19:24               ` Robert Hancock
2008-01-20 21:31                 ` Rafael J. Wysocki
2008-01-21  7:48               ` Daniel Barkalow
2008-01-20 19:16             ` Andi Kleen
  -- strict thread matches above, loose matches on Subject: below --
2008-01-20 22:06 Tomasz Chmielewski
2008-01-20 22:26 ` Rafael J. Wysocki
2008-01-21 10:11 ` Matthew Garrett
     [not found] <fa.tHyDHqRNYFvp4N4SR4JtJRuqh0k@ifi.uio.no>
2008-01-21 23:59 ` Robert Hancock

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