11-HEAD i386 on T400 - rundown

[Adrian Chadd]

Hi,

I recently upgraded my Lenovo T400 to the latest i386 -HEAD (as of last night.)

The 30 second version:

Works:

* it boots fine!
* xorg works fine, but I haven't tested out 3d;
* wifi works fine (intel 5100 abgn wifi);
* bluetooth isn't tested, but not much has changed here, so I expect it will be;

Doesn't work:

* USB port power still doesn't come back after a resume.

Things that may work better:

* reboot was never 100% reliable; I'll have to reboot a hundred times
to see if it's still flaky;
* same with suspend/resume, but I've not had it resume badly yet.

Now, for the power consumption bits:

Using acpiconf -i0, I can get the power draw down to around 14W when
idle, running xorg:

* no firefox/chrome, as those do all kinds of high resolution timer
events that we dutifully meet;
* iwn(4) in powersave mode (ifconfig wlan0 create wlandev iwn0 powersave);
* bluetooth disabled;
* LCD brightness turned further down.

Now, I'd like to find ways to turn the power down. Vague forum
searches show that this _should_ get down to around 10W. I can't think
of anything else to do system-wise - I don't know if it's hard disk
related (I think it's always spinning, that may be a problem); I don't
know if it's GPU related (ie, if the GPU is constantly on and we're
not doing "sleep" things.)

I'm going to play with booting it in single-CPU mode and see if that
drops power consumption. If so, I wonder if for mostly-idle workloads
the "right" thing to do is just leave the other CPUs in an idle state
and only start scheduling work on them if the run queue gets too deep.

Comments?

I'll try this on an X220 in a couple weeks. Hopefully the latest -HEAD
and xorg suspend/resumes video correctly!

Thanks,



-adrian