Hi,
I am a little confused about several things around ACPI and C-States.
Maybe I misunderstood a few things and due to that I did not hit the
right keywords in search engines and now I hope you can help me.
First of all. I am running a old ASRock 760GM-GS3 with a AMD Athlon II
X2 240 C3-Stepping (AM3) as a small homeserver, doing some
virtualisation and vdr stuff on it. Most of the time the cpu is idle, so
I started little time ago to reduce the power consumption. Today, it is
using 42W idling. And I am just courious if I might get it lower.
In the BIOS I've got a setting to enable C1E. Doing so, results in
* [ 0.161189] process: System has AMD C1E enabled
* [ 0.161202] process: Switch to broadcast mode on CPU1
* [ 0.161660] process: Switch to broadcast mode on CPU0
shown in dmesg. Followed by
* [ 0.676465] ACPI: processor limited to max C-state 1
some lines below.
When I disable C1E in the BIOS, none of the lines is shown up.
Since C1 is not the same as C1E, it seems there is some limit.
So, I tried to figure out if C1E is used, and which C-States are used
overall.
I read through many sites, some of them were stating that /proc/acpi is
the place to take a look, others are telling /sys/power or
/sys/devices/system/cpu/ is the right place to find information about
C-States. Again others are telling me acpitool -c will show me C-States.
For me, it shows only
* # acpitool -c
* CPU type : AMD Athlon(tm) II X2 240 Processor
* Min/Max frequency : 800/2800 MHz
* Current frequency : 800 MHz
* Frequency governor : ondemand
* Freq. scaling driver : acpi-cpufreq
* Cache size : 800.000 KB
* Bogomips : 5613.25
* Bogomips : 5613.25
* Function Show_CPU_Info : could not read directory /proc/\
acpi/processor/
* Make sure your kernel has ACPI processor support enabled.
Tested with kernel version 3.7.0 and 3.2.12 and
* [Deprecated] /proc/acpi/*
switch in kernel config enabled.
The modules are loaded, too. But the only file in /proc/acpi is called
'wakeup'.
Can someone help me getting back on the track? What can I do to show up
the used c-states?
Cheers,
Sebastian
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