C-states only used _with_ load on Acer Extensa 5220 Celeron M Notebook (2.6.24 x64)

[Dennis Jansen]

I found a trick. C2 is used after S3. It makes a big difference as shown below.

Before suspend its 99% C0, after suspend its 99% C2
-- and that's with pretty much the same programs running.

I've made a diff of powertop -d before and after the suspend
(attached) and the interesting part are the first lines:
C0 (Prozessor läuft)    (99,9%)
| C0 (Prozessor läuft)    ( 0,7%)
C2                0,0ms ( 0,1%)
| C2               54,7ms (99,3%)
Aufwachen pro Sekunde : 80,9    Intervall: 15,0s
| Aufwachen pro Sekunde : 18,3    Intervall: 15,0s
 17,5% (  4,0)   <kernel module> : usb_hcd_poll_rh_status ( r
| 18,5% (  4,0)   <kernel module> : usb_hcd_poll_rh_status (r
  9,1% (  2,1)              Xorg : do_setitimer (it_real_fn)
*| 13,9% (  3,0)       <interrupt> : acpi
  8,8% (  2,0)     <kernel core> : clocksource_register (clo
| 9,0% (  1,9)              Xorg : do_setitimer (it_real_fn)
2,6% (  0,6)       <interrupt> : uhci_hcd:usb4, b43                    <
2,0% (  0,5)    NetworkManager : schedule_timeout (process  <
1,8% (  0,4)            xwrits : schedule_timeout (process          <
1,2% (  0,3)   guidance-power- : schedule_timeout (process    <

While some thing did disappear, I think the acpi interrupt that showed
up is interesting, isn't it?

My guess is that in the suspend process either the acpi code or the
bios resets something to where it should be at.

And there must be something "hogging" the cpu without showing up in
top or powertop, because the shown wake reasons before suspend don't
sum up to the shown wakes per second (attached
powertop-allbeforesusp).

Any ideas?

Cheers,

Dennis

On Feb 11, 2008 3:35 AM, Len Brown <lenb at kernel.org> wrote:

> 98.9% C0 means that the system is busy all the time
> and that looking at idle time is simply not interesting
> b/c there really isn't any.
>
> run top to figure out what is hogging the cpu and kill it.
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