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Date:      Thu, 17 Jan 2008 11:15:35 +1030
From:      "Daniel O'Connor" <doconnor@gsoft.com.au>
To:        freebsd-current@freebsd.org
Cc:        njl@freebsd.org, bruno@freebsd.org, Stefan Lambrev <stefan.lambrev@moneybookers.com>, Igor Mozolevsky <igor@hybrid-lab.co.uk>, Dag-Erling =?utf-8?q?Sm=C3=B8rgrav?= <des@des.no>, Maxim Sobolev <sobomax@digifonica.com>
Subject:   Re: powerd adaptive mode latching
Message-ID:  <200801171115.43663.doconnor@gsoft.com.au>
In-Reply-To: <478930D2.90806@digifonica.com>
References:  <a2b6592c0801110351l382959ffh1d55f2bcd2e6ca1b@mail.gmail.com> <a2b6592c0801111119r148d3697hf75a59b7bf74d540@mail.gmail.com> <478930D2.90806@digifonica.com>

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On Sun, 13 Jan 2008, Maxim Sobolev wrote:
> I wonder if somebody did measurement of power consumption with powerd
> and without it on typical tasks. There is very interesting idea in
> the last issue of ACM Queue that it might be much more beneficial to
> run CPU at the full speed and then switch it to low-power mode as
> soon as possible in the idle loop than to run longer at reduced speed
> for a longer period of time.

I did a bit of testing on a road trip once using acipconf -i 0 to=20
measure current draw.

One problem with it is that it lags behind actual usage by a few seconds=20
(presumably averaging it).

Still, at full steam (md5'ing /dev/zero at 1.4GHz) my laptop uses ~34W=20
vs ~20W idle (which is ~300MHz depending on what KDE is doing :).

Turning the LCD off saves about 4W too.

I set my powerd flags like so..
powerd_enable=3D"YES"
powerd_flags=3D"-i 70 -r 30 -a adaptive -b adaptive -n adaptive -p 200"

=2D-=20
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C

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