I updated my Asus P5B Deluxe BIOS with no luck (this latest BIOS is about 1
month old). Still no power states. I would be nice to know if _any_ desktop
C2D mobos have these C-states? (In x86_64 system).
I think I never mentioned:
I'm using 126.96.36.199 (actually gentoo-sources-2.6.21-r1)
My CPU is E6400.
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On Tue, 22 May 2007 17:14:45 +0000
I observe the same problem with Gigabyte 965P-DS4, and there are at
least two causes - 1) MP supported flag in FADT is missing (so
CPU_HOTPLUG would be necessary), and 2) C2 latency is set to 101,
while the maximum allowed in the kernel is 100.
However, from the power consumption and the CPU temperature it seems
that the power saving works anyway, so I'll live with it.
I also don't have C-states on my DG965RY intel board with core 2 duo E6400
Any board can support C-states ether by fixed ACPI set of registers or by a
set of functions in acpi tables.
On my system ICH8 (and I almost sure you got it too), doesn't support
And there is no other magic chip that can put cpu in c-state (on my system) ,
so acpi has no "set of functions to do that"
So I guess that on my board there is no physical support for C-states, and
this could be true for you too.
Anyway monitor/mwait can put cpu in C1, and having apic-stops-in-c2/c3 bug,
I don't think those states are that needed.
The Speedstep support is a different thing at all:
Agian acpi has a function that can change cpu clock speed to fixed values,
And yes on my board it also has only two values: 1500 and 2130.
This support is implemented by accessing the clock chip
(Actualy on my system acpi writes a magic value to one of ICH8 registers, and
this triggers a SMM that changes the clock)
And the last thing is about throtting states your and mine system does
Throttling states are states that make system halt cpu for some % of time,
Yes there are 8 such states. You can enter one of those by writeing a state
number to /proc/acpi/processor/*/throttling (I assume you have ICH8 or
Also ICH*'s throtting states are system global, this is why I wrote "/*/"
If you change it for one core, it will be changed for other.
They are supported by fixed acpi function (by ICH8)
My 2 cents.