Thinkpad Edge 13 Intel C-states missing

I installed openSUSE 11.3 64-bit on my Thinkpad Edge 13 with Intel Core 2 Duo and in /proc/acpi/processor/cpuX/power only the C-states C1 and C2 are shown. Naturally, the battery life is terrible.

I already dumped the DSDT and SSDTs, decompiled them and they contain several different _CST configurations - some with C3 state, some only with C1 and C2 defined. One of these configurations is chosen according to some variables which however I do not know the meaning of. I tried making my own custom DSDT/SSDT with only one _CST configuration including C3, but it did not seem to get included properly during boot. I have not yet tried to load the DSDT with the ramdisk.

Any ideas?

I found a web page with lots of good info you might want to read here:

Saving power with Linux on Intel hardware

You did not mention the desktop that you are using, but CPU setup is critical to power usage. It must be setup for dynamic (ondemand) in KDE for the best performance to power usage setup. If you have moved to KDE 4.5, you must load the YaST power module in order to control your CPU operation as it has been removed from KDE in that version. I do not know about its usage in Gnome.

I also have a way you can upgrade your kernel to perhaps 2.6.36 to get the latest Intel performance, but don’t know if it affects the issue you have right now. Message #26 has the most recent version of sakc:

S.A.K.C - SuSE Automated Kernel Compiler

You can get the most recent kernel from here:

The Linux Kernel Archives

You know that new kernels and the most recent version of openSUSE (and perhaps waiting on using KDE 4.5 for now) is about the best we can do on Laptop power usage. So much depends on the hardware selected and its support in Linux.

Thank You,

Turns out the two C-states correspond to C1 and C4wait (according to powertop) and after some tweaking (linuxpowertop.org and also lesswatts.org were very helpful) I am now down to about 6.2-6.4W while idle. Also I needed to update the kernel since 2.6.34 included with 11.3 showed some inconsistent power drain on cold boot vs reboot. I also noticed the idle power consumption increases by about 0.5W when putting the system to suspend and then waking it up. This also persists with the latest kernel 2.6.37-rc3 I am running right now. Strange. Probably some device that resets to defaults when waking from suspend and not properly disabled or set to power save after that.

Turns out the two C-states correspond to C1 and C4wait (according to powertop) and after some tweaking (linuxpowertop.org and also lesswatts.org were very helpful) I am now down to about 6.2-6.4W while idle. Also I needed to update the kernel since 2.6.34 included with 11.3 showed some inconsistent power drain on cold boot vs reboot. I also noticed the idle power consumption increases by about 0.5W when putting the system to suspend and then waking it up. This also persists with the latest kernel 2.6.37-rc3 I am running right now. Strange. Probably some device that resets to defaults when waking from suspend and not properly disabled or set to power save after that.
So does this mean you are now running using less power than before the fixes you have applied? Why did you decide to go with kernel 2.6.37-rc3? While I have tried it out, kernel 2.6.36.1 Final is out and very stable. You never know what you might get into there with a pre-release kernel version.

Thank You,

I was at over 10W when I started, but that was with brightness set to maximum.

I tried the 2.6.36-1 kernel, but it caused my system to lock-up during boot so I had to do a hard reset. Forgot what the error msg was exactly, but 2.6.37-rc3 runs fine so they must have fixed it.

I just tried kernel 2.6.35.9 and now I am down to only 6.0W. Since this guy is probably more stable than the latest bleeding-edge 2.6.37 rc I think I will stick with it.

I just tried kernel 2.6.35.9 and now I am down to only 6.0W. Since this guy is probably more stable than the latest bleeding-edge 2.6.37 rc I think I will stick with it.
That sounds very good to hear (That you reduced your power consumption). Kernel differences are not just the presence or absence of new hardware modules, but how the kernel has been configured and even what standard hardware modules are present. The SAKC script allows you to configure your kernel for such things. However, information on the exact settings seem to be lacking most of the time. There is help for most items, but it would be hard to call it a full description of your options. Still, I have found a lot, including debug and experimental stuff present, which can be removed. Of course, I am looking for more speed, not less power consumption. I am sure after I configured a kernel for you it would be using 12 watts and not six. lol!

Thank You,