Comment 82 for bug 524281

I tested Brian Roger's 2.6.35-rc5 kernel with the scheduling changes and saw little difference on a Intel(R) Core(TM)2 Duo CPU (Thinkpad X300). Here is the powertop output with a firefox browser open:

Wakeups-from-idle per second : 308.9 interval: 15.0s
no ACPI power usage estimate available
Top causes for wakeups:
  30.6% ( 79.3) [kernel scheduler] Load balancing tick
  19.2% ( 49.9) [extra timer interrupt]
  16.5% ( 42.9) [kernel core] hrtimer_start (tick_sched_timer)
   0.1% ( 0.3)D upowerd
   5.9% ( 15.2) [iwlagn] <interrupt>
   0.3% ( 0.8)D gnome-settings-
   4.6% ( 11.9) firefox-bin
   4.2% ( 11.0) nautilus
   3.9% ( 10.0) syndaemon
   3.1% ( 8.1) [kernel core] usb_hcd_poll_rh_status (rh_timer_func)
   2.2% ( 5.7) [ahci] <interrupt>
   1.6% ( 4.3) [TLB shootdowns] <kernel IPI>
   0.0% ( 0.0)D flush-8:0
   1.2% ( 3.1) Xorg

Compared with the standard Lucid kernel, the Load balancing tick wakeups are down about 10% while the hrtimer_start (tick_sched_timer) are up some.

These results compare with using the Karmic kernel where wakeups were halved.

Brian: Did you apply the patch noted in the lkml thread I posted above? The claim there is a substantial wakeups reduction with that applied.