From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Tomasz Chmielewski <mangoo@wpkg.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: Celeron Core
Date: Mon, 21 Jan 2008 10:11:48 +0000 [thread overview]
Message-ID: <20080121101147.GB2785@srcf.ucam.org> (raw)
In-Reply-To: <4793C5CA.5060100@wpkg.org>
On Sun, Jan 20, 2008 at 11:06:02PM +0100, Tomasz Chmielewski wrote:
> 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).
Voltage scaling isn't the only component of CPU power management. Intels
have supported low power states on idle since the Pentium 90 (Cyrix had
"Suspend on HALT" earlier than that), which means that an idle processor
takes less power than one executing code. On anything even vaguely
modern, throttling will not save you any significant power compared to
the C state support.
> For example, a server that doesn't crunch any numbers at night will
> certainly use less power when throttled.
Have you got benchmark figures for this?
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2008-01-21 10:25 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-20 22:06 PROBLEM: Celeron Core Tomasz Chmielewski
2008-01-20 22:26 ` Rafael J. Wysocki
2008-01-21 10:11 ` Matthew Garrett [this message]
[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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