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Date:      Thu, 08 Sep 2005 17:18:54 -0700
From:      Nate Lawson <nate@root.org>
To:        Hajimu UMEMOTO <ume@freebsd.org>
Cc:        acpi@freebsd.org
Subject:   Re: Another acpi_thermal nit
Message-ID:  <4320D4EE.3020405@root.org>
In-Reply-To: <yge4q8vsg59.wl%ume@mahoroba.org>
References:  <20050908153235.BFA955D08@ptavv.es.net> <yge4q8vsg59.wl%ume@mahoroba.org>

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Hajimu UMEMOTO wrote:

>>>>>>On Thu, 08 Sep 2005 08:32:35 -0700
>>>>>>"Kevin Oberman" <oberman@es.net> said:
> 
> 
> oberman> It would really be nice to be able to slow the system below where
> oberman> acpi_thermal has lowered it. I just don't know if this is a matter of
> oberman> code or a BIOS issue with no way out.
> 
> Yup, I understand your needs.  But, it is rather by design of
> acpi_thermal.  However, you can stop passive cooling by setting
> hw.acpi.thermal.tz0.passive_cooling to zero even when passive cooling
> is active.  You can do the following step:
> 
>   1) sysctl hw.acpi.thermal.tz0.passive_cooling=0
>   2) Set your favorite CPU speed by dev.cpu.0.freq
>   3) sysctl hw.acpi.thermal.tz0.passive_cooling=1

Our acpi_thermal code switches between active and passive cooling 
strategies when going off battery power.  So it is likely that your 
system only uses passive cooling so aggressively when offline.

ume@'s suggestion is the best approach I think.

-- 
Nate



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