Comment 12 for bug 760131

To quantify my statement (posting #9) these are results of a 5min powertop dump in GDM with firefox+thunderbird idling for 2.6.36-1

Cn Avg residency
C0 (cpu running) ( 2.5%)
polling 0.0ms ( 0.0%)
C1 mwait 0.0ms ( 0.0%)
C2 mwait 0.3ms ( 0.5%)
C4 mwait 13.9ms (97.0%)
P-states (frequencies)
Turbo Mode 1.0%
  2.50 Ghz 0.0%
  1.60 Ghz 0.2%
  1200 Mhz 0.1%
   800 Mhz 98.6%
Wakeups-from-idle per second : 91.4 interval: 300.0s
no ACPI power usage estimate available
Top causes for wakeups:
  16.7% ( 10.8) kworker/0:0
  16.3% ( 10.5) [ata_piix] <interrupt>
  14.3% ( 9.2) [kernel scheduler] Load balancing tick
  12.4% ( 8.0) apt-check
   6.9% ( 4.4) [kernel core] hrtimer_start (tick_sched_timer)
   3.2% ( 2.0) cpufire_applet
   3.1% ( 2.0) [nvidia] <interrupt>
   3.0% ( 1.9) firefox-bin
...

and 2.6.38-8
Cn Avg residency
C0 (cpu running) ( 2.8%)
polling 0.0ms ( 0.0%)
C1 mwait 0.0ms ( 0.0%)
C2 mwait 0.2ms ( 0.3%)
C4 mwait 11.8ms (96.9%)
P-states (frequencies)
Turbo Mode 1.2%
  2.50 Ghz 0.1%
  1.60 Ghz 0.2%
  1200 Mhz 0.2%
   800 Mhz 98.3%
Wakeups-from-idle per second : 97.5 interval: 300.0s
no ACPI power usage estimate available
Top causes for wakeups:
  33.1% ( 25.4) kworker/0:0
  13.9% ( 10.7) [kernel scheduler] Load balancing tick
  13.9% ( 10.6) [extra timer interrupt]
   8.5% ( 6.5) [ata_piix] <interrupt>
   4.4% ( 3.3) [ahci, firewire_ohci] <interrupt>
   2.9% ( 2.2) cpufire_applet
   2.6% ( 2.0) firefox-bin
   2.6% ( 2.0) [nvidia] <interrupt>
   2.1% ( 1.6) gnome-terminal

The wakeup rate for 2.6.38 is higher indeed but not as excessive as seen by others.