[ltp] no C3 state in X - but i do get to C3 with X running but not displayed on screen

[Brad Langhorst]

I've learned something interesting about C3 state on 2.6.11.6 T40p

when i'm at vt1 my computer spends time in C3 state
but when i'm in X C3 never gets entered...  I don't have to stop X to
enter C3 - i just have to switch to another virtual terminal.

I have ehci_hcd and uhci_hcd loaded (but no devices attached).

Looks like the "bus master activity" is what's keeping my cpu from going
to C3... any ideas how to eliminate that activity?
I'm going to try turning off acceleration to see if that does it.

brad
---------------------------------------------------------------
from vc1 (with X running on vc7)
up:/proc/acpi/processor/CPU# cat power
active state:            C4
max_cstate:              C8
bus master activity:     00000000
states:
    C1:                  type[C1] promotion[C2] demotion[--]
latency[001] usage[00000010]
    C2:                  type[C2] promotion[C3] demotion[C1]
latency[001] usage[08066712]
    C3:                  type[C3] promotion[C4] demotion[C2]
latency[085] usage[00014561]
   *C4:                  type[C3] promotion[--] demotion[C3]
latency[185] usage[00134347]
up:/proc/acpi/processor/CPU# date
Wed Apr  6 11:06:53 EDT 2005
up:/proc/acpi/processor/CPU# cat power
active state:            C2
max_cstate:              C8
bus master activity:     00004000
states:
    C1:                  type[C1] promotion[C2] demotion[--]
latency[001] usage[00000010]
   *C2:                  type[C2] promotion[C3] demotion[C1]
latency[001] usage[08074472]
    C3:                  type[C3] promotion[C4] demotion[C2]
latency[085] usage[00015235]
    C4:                  type[C3] promotion[--] demotion[C3]
latency[185] usage[00139179]
------------------------------------------------------------------
from X term

bwlang@up:/usr/src$ cat /proc/acpi/processor/CPU/power
active state:            C2
max_cstate:              C8
bus master activity:     01000010
states:
    C1:                  type[C1] promotion[C2] demotion[--]
latency[001] usage[00000010]
   *C2:                  type[C2] promotion[C3] demotion[C1]
latency[001] usage[07954599]
    C3:                  type[C3] promotion[C4] demotion[C2]
latency[085] usage[00014365]
    C4:                  type[C3] promotion[--] demotion[C3]
latency[185] usage[00133343]
bwlang@up:/usr/src$ date
Wed Apr  6 11:05:12 EDT 2005
bwlang@up:/usr/src$ cat /proc/acpi/processor/CPU/power
active state:            C2
max_cstate:              C8
bus master activity:     10000100
states:
    C1:                  type[C1] promotion[C2] demotion[--]
latency[001] usage[00000010]
   *C2:                  type[C2] promotion[C3] demotion[C1]
latency[001] usage[07969362]
    C3:                  type[C3] promotion[C4] demotion[C2]
latency[085] usage[00014365]
    C4:                  type[C3] promotion[--] demotion[C3]
latency[185] usage[00133343]