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Date:      Wed, 10 Dec 2003 10:04:51 -0800 (PST)
From:      Nate Lawson <nate@root.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        current@freebsd.org
Subject:   RE: ACPI throttling changes
Message-ID:  <20031210100342.B46577@root.org>
In-Reply-To: <XFMail.20031210114404.jhb@FreeBSD.org>
References:  <XFMail.20031210114404.jhb@FreeBSD.org>

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On Wed, 10 Dec 2003, John Baldwin wrote:
> On 10-Dec-2003 Nate Lawson wrote:
> > I'm working on a shared CPU frequency control driver.  One step is to
> > remove some of the autonomy of the throttling portion of acpi_cpu.
> > Please test this patch if you have a machine which supports throttling.
> > With this patch, throttling can be changed by doing:
> >
> >    sysctl hw.acpi.cpu.current_speed=X
> >
> > where X is some number between 1 and hw.acpi.cpu.max_speed.  It is no
> > longer driven by AC line transitions.  Run a CPU benchmark like this one
> > to make sure the throttling transition still works with this patch.
> >
> >     dd if=/dev/zero bs=1m count=500 | md5
> >
> > This is part of a larger work.  Don't worry, it won't be committed until
> > general CPU frequency control is done so no loss of functionality will be
> > committed.
>
> We need to support using throttling for passive cooling btw.  My new laptop
> I just got has no active cooling support, but does have _TC1 and _TC2 objects
> in its thermal zone.  Are you going to add that?

Eventually.  The first step is to get a general frequency control driver
working.  It will also do throttling as well as speedstep, longrun, etc.
The step after that is to change acpi_thermal to use that driver for
passive cooling.

-Nate



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