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Date:      Sun, 16 Nov 2003 19:06:38 -0800 (PST)
From:      Nate Lawson <nate@root.org>
To:        Lukas Ertl <l.ertl@univie.ac.at>
Cc:        current@freebsd.org
Subject:   Re: cvs commit: src/sys/dev/acpica acpi_cpu.c src/share/man/man4   acpi.4 src/sys/conf files src/sys/modules/acpi Makefile
Message-ID:  <20031116190312.M58542@root.org>
In-Reply-To: <20031116214644.T624@korben.in.tern>
References:  <20031115121418.U54473@root.org> <20031116214644.T624@korben.in.tern>

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On Sun, 16 Nov 2003, Lukas Ertl wrote:
> On Sat, 15 Nov 2003, Nate Lawson wrote:
>
> > Please test this to be sure that it boots ok on your machine, especially
> > SMP boxes.  Throttling should still work ok also.
>
> Seems to work here:
>
> hw.acpi.cpu.cx_supported: C1/1 C2/1 C3/85 C3/185
> hw.acpi.cpu.cx_lowest: 0
> hw.acpi.cpu.cx_history: 173839/0 0/0 0/0 0/0
>
> I've no idea if it actually has an effect.

Yes, it is working fine for you.  Those states look like a Centrino.
(I've gotten familiar with how different chipsets look).  In any case, the
default is to just use C1 which is the same as previous behavior.  To get
better power savings, set cx_lowest to 1, 2, or 3.  The counters in the
appropriate slots will go up in cx_history.  From your latencies, you
should be fine with a value of 1 and see a slight performance loss for 2
or 3 (but very small).  I'd be interested in any testing results you find
for each of those values (in terms of power and performance).

-Nate



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