[ltp] Significant power savings with new linux kernel?

[Christos Papadopoulos]

I just upgraded to 2.6.30.8-64.fc11.i586 #1 SMP. In the past, powertop
reported power usage of around 10.5W, after applying all the commands
it suggested and LCD intensity set to min. With the new kernel I see
power drain down to around 8.7 - 8.9W, numbers I have not even dreamed
before. The laptop is a X40 running Fedora 11.

I am very happy, but does anyone know what happened?

Christos.

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        ( 4.7%)         1.60 Ghz     1.6%
C0                0.0ms ( 0.0%)         1500 Mhz     0.0%
C1 halt           0.0ms ( 0.0%)         1400 Mhz     0.0%
C2                1.9ms ( 4.5%)         1100 Mhz     0.2%
C3                3.4ms ( 3.1%)          600 Mhz    98.2%
C4               11.6ms (87.7%)
Wakeups-from-idle per second : 108.3    interval: 15.0s
Power usage (ACPI estimate): 8.7W (5.5 hours) (long term: 9.7W,/4.9h)

Top causes for wakeups:
  29.7% ( 63.5)           firefox : hrtimer_start_range_ns (hrtimer_wakeup)
  29.6% ( 63.2)       <interrupt> : uhci_hcd:usb2, yenta, i915@pci:0000:00:02.0
  20.4% ( 43.5)     <kernel core> : hrtimer_start_range_ns (tick_sched_timer)
  10.9% ( 23.2)       <interrupt> : PS/2 keyboard/mouse/touchpad
   4.5% (  9.7)       <interrupt> : ipw2200
   1.0% (  2.2)       <interrupt> : acpi
   0.8% (  1.7)     <kernel core> : hrtimer_start (tick_sched_timer)
   0.4% (  0.8)       <interrupt> : ata_piix
   0.2% (  0.5)       <interrupt> : eth0
   0.2% (  0.5)    NetworkManager : __mod_timer (e1000_watchdog)
   0.2% (  0.5)     <kernel core> : __mod_timer (neigh_periodic_timer)
   0.2% (  0.5)   <kernel module> : __mod_timer (neigh_periodic_timer)
   0.2% (  0.5)          events/0 : queue_delayed_work (delayed_work_timer_fn)
   0.2% (  0.5)               gpm : hrtimer_start_range_ns (hrtimer_wakeup)
   0.2% (  0.4)    NetworkManager : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)    gnome-terminal : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)   gnome-settings- : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)       gnome-panel : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)   gnome-screensav : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.2)              ntpd : __mod_timer (death_by_timeout)
   0.1% (  0.1)        rc.sysinit : __mod_timer (commit_timeout)
   0.1% (  0.1)     <kernel core> : __mod_timer (neigh_timer_handler)