cvs commit: src/sys/dev/acpica acpi_cpu.c src/share/man/man4 acpi.4 src/sys/conf files src/sys/modules/acpi Makefile

Nate Lawson nate at
Sun Nov 16 19:06:36 PST 2003

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).


More information about the freebsd-current mailing list