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Date:      Wed, 10 Aug 2005 12:01:18 +0200
From:      Tijl Coosemans <tijl@ulyssis.org>
To:        freebsd-acpi@freebsd.org
Cc:        ducrot@freebsd.org
Subject:   Re: 5-STABLE cpufreq hotter than est from ports
Message-ID:  <200508101201.19489.tijl@ulyssis.org>
In-Reply-To: <20050808180345.CABF35D08@ptavv.es.net>
References:  <20050808180345.CABF35D08@ptavv.es.net>

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On Monday 08 August 2005 20:03, Kevin Oberman wrote:
> > From: Tijl Coosemans <tijl@ulyssis.org>
> > Date: Mon, 8 Aug 2005 16:18:00 +0200
> >
> > In my experience throttling doesn't really gain that much. There's
> > almost no difference between running at 600MHz/100% and
> > 600MHz/12.5%, except that it is 8 times slower, so I've set
> > debug.cpufreq.lowest to 400 to limit the performance drop.
>
> Odd. I don't see that at all. I am running at either 1.8 GHz or 1.2
> GHz and the performance ramps almost in lock-step with the setting
> and power consumption does, as well. Without your patch, using the
> values of dev.cpu.0.freq that run the CPU at the slower speed (1.2
> GHz), I get the following:
> dev.cpu.0.freq	Temp.	Savings
> 1200		73
> 1050		69	 5.5%
>  750		64	12.3%
>  600		62	15.1%
>  300		58	20.5%
>  150		54	25.0%
> The lowest 1.8 GHz value (1350) results in 85.I find these power
> savings to be significant.
>
> For power consumption I run the CPU at 100% until the CPU temperature
> stabilizes. I realize that this is only an approximation of power
> consumption, but I think it's close enough.

I've done this too now and I must admit throttling does seem to have an=20
effect on power consumption, though it seems to be less and less=20
effective with lower absolute settings.

1600/100%  (1600) 69=B0C
1600/12.5% (200)  55=B0C

600/100%   (600)  48=B0C
600/12.5%  (75)   45=B0C

=46or me, dropping to the lowest frequency (75MHz) is just way too=20
expensive.



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