From: Robert Hancock <hancockr@shaw.ca>
To: David Newall <davidn@davidnewall.com>
Cc: Andi Kleen <andi@firstfloor.org>, Matt Mackall <mpm@selenic.com>,
Chodorenko Michail <misha@one.by>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: Celeron Core
Date: Sun, 20 Jan 2008 12:24:09 -0600 [thread overview]
Message-ID: <479391C9.9020004@shaw.ca> (raw)
In-Reply-To: <fa.LZLUxfR64dAZFPtin9JNet7ieiY@ifi.uio.no>
David Newall wrote:
> Andi Kleen wrote:
>>> Isn't it the case that an idle machine will use
>>> less power when throttled than when not?
>>>
>> No that is not the case (not even on old CPUs)
>>
> Then why would it run cooler? What generates the heat when not
> throttled? What stops generating heat when throttled? And you say this
> happens without reducing power consumption? I'm not convinced. I'm a
> long way from that.
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.
Real CPU clock throttling schemes like SpeedStep, PowerNow, etc.
actually do increase performance per watt when they kick in.
next parent reply other threads:[~2008-01-20 18:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[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 [this message]
2008-01-20 19:14 ` PROBLEM: Celeron Core 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
[not found] <fa.tHyDHqRNYFvp4N4SR4JtJRuqh0k@ifi.uio.no>
2008-01-21 23:59 ` Robert Hancock
2008-01-20 22:06 Tomasz Chmielewski
2008-01-20 22:26 ` Rafael J. Wysocki
2008-01-21 10:11 ` Matthew Garrett
-- strict thread matches above, loose matches on Subject: below --
2008-01-18 19:06 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
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
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