From: Tomasz Chmielewski <mangoo@wpkg.org>
To: LKML <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: Celeron Core
Date: Sun, 20 Jan 2008 23:06:02 +0100 [thread overview]
Message-ID: <4793C5CA.5060100@wpkg.org> (raw)
>> Clock throttling is not likely to save your battery, unless you have
>> tasks that are running at 100% CPU for an unlimited time or something,
>> and you force your CPU to throttle. Normally most people have tasks that
>> run and then the CPU idles - loading an email, displaying a web page,
>> etc. Clock throttling will just make these tasks utilize the CPU for a
>> longer time proportional to the amount clock throttling and therefore
>> negate any gains in battery usage.
Aren't you forgetting about CPUfreq governors? Which mean: use the
maximum CPU frequency when the system is busy, throttle down (or lower
voltage) when the system is idle.
So yes, throttling will save the battery.
Besides, not all CPUs support power management (voltage control).
> IMO clock throttling (as opposed to the reduction of the frequency of an idle
> CPU) is only useful for preventing the CPU from overheating.
And for reducing power on CPUs that can't do any power management, just
throttling.
For example, a server that doesn't crunch any numbers at night will
certainly use less power when throttled.
--
Tomasz Chmielewski
http://wpkg.org
next reply other threads:[~2008-01-20 22:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-20 22:06 Tomasz Chmielewski [this message]
2008-01-20 22:26 ` PROBLEM: Celeron Core Rafael J. Wysocki
2008-01-21 10:11 ` Matthew Garrett
[not found] <fa.tHyDHqRNYFvp4N4SR4JtJRuqh0k@ifi.uio.no>
2008-01-21 23:59 ` Robert Hancock
[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 --
2008-01-18 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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