[Bug 524281] Re: Tens of wakes per second in "[kernel scheduler] Load balancing tick" on Core 2 Duo even with only 1 core enabled

[Michael Christensen]

The latest kernel update, 2.6.32-25-generic, has changed things a bit. At least in my case. Granted, I have changed some things to prevent cpu wakeups by adding hpet=force nohz=off highres=off to the GRUB CMDLINE since the kernel update 2.6.32-24 update. At that time Load Balancing ticks were still appearing, even when idle. With the 2.6.32-25 update there are wakeups but under a different name: [Rescheduling interrupts] <kernel IPI>. What is more surprising is that the wakeups are not appearing while idle which they were with the 2.6.32-24 and others before.
I use a selfmade powersaving script but tested wakeups in Powertop before I activated the script and here are the results. NB! I have turned off some services. This was done on a desktop C2D E6550 with Lucid installed.

When idle (no mouse movement or anything): 
Wakeups-from-idle per second :  7,6     interval: 10,0s
no ACPI power usage estimate available

Top causes for wakeups:
  30,5% (  4,0)   [kernel core] usb_hcd_poll_rh_status (rh_timer_func)
  15,3% (  2,0)   [kernel core] clocksource_watchdog (clocksource_watchdog)
   7,6% (  1,0)   [uhci_hcd:usb3, nvidia] <interrupt>
   7,6% (  1,0)   gvfs-afc-volume
   7,6% (  1,0)   [kernel core] nv_kern_rc_timer (nv_kern_rc_timer)
   3,1% (  0,4)   nautilus
   2,3% (  0,3)   clock-applet
   2,3% (  0,3)   gnome-panel
   2,3% (  0,3)   gedit
   1,5% (  0,2)   rtkit-daemon
   1,5% (  0,2)   [kernel core] inc_rt_group (sched_rt_period_timer)
   1,5% (  0,2)   gnome-terminal
   1,5% (  0,2)   gnome-settings-

Here is when watching a HD movie:
Wakeups-from-idle per second : 150,8    interval: 10,0s
no ACPI power usage estimate available

Top causes for wakeups:
  42,3% (126,7)   [ata_piix, ata_piix, HDA Intel] <interrupt>
  20,9% ( 62,5)   [Rescheduling interrupts] <kernel IPI>
  16,4% ( 49,0)   [uhci_hcd:usb3, nvidia] <interrupt>
   8,5% ( 25,6)   gnome-mplayer
   8,1% ( 24,4)   mplayer
   1,3% (  4,0)   [kernel core] usb_hcd_poll_rh_status (rh_timer_func)
   0,7% (  2,0)   [kernel core] clocksource_watchdog (clocksource_watchdog)
   0,3% (  1,0)   [kernel core] inc_rt_group (sched_rt_period_timer)
   0,3% (  1,0)   gvfs-afc-volume
   0,3% (  1,0)   [kernel core] nv_kern_rc_timer (nv_kern_rc_timer)
   0,1% (  0,3)   gnome-terminal
   0,1% (  0,3)   gedit
   0,1% (  0,3)   gnome-settings-
   0,1% (  0,3)   clock-applet
   0,1% (  0,3)   gnome-panel
   0,1% (  0,2)   rtkit-daemon

-- 
Tens of wakes per second in "[kernel scheduler] Load balancing tick" on Core 2 Duo even with only 1 core enabled
https://bugs.launchpad.net/bugs/524281
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