Что такое Kworker и SignalSender?

Что такое Kworker и SignalSender и почему они используют так много ЦП? Статистика от Powertop дала эти цифры. Как я могу его оптимизировать?

Top causes for wakeups:
28.4% (420.4)   PS/2 keyboard/mouse/touchpad interrupt
14.8% (219.5)   [kernel scheduler] Load balancing tick
14.0% (206.8)   kworker/0:0
8.4% (124.9)   SignalSender
7.7% (114.5)   [Rescheduling interrupts] <kernel IPI>

Ядро:

Kernel version - Linux xyz-xx-xx-110-1100 2.6.38-11-generic #48-Ubuntu SMP 
Fri Jul 29 19:05:14 UTC 2011 i686 i686 i386 GNU/Linux   

PowerTop Stats

Top causes for wakeups:
18.5% (203.6)   [kernel scheduler] Load balancing tick
18.5% (203.5)   kworker/0:0
16.1% (176.6)   [Rescheduling interrupts] <kernel IPI>
14.2% (156.2)   SignalSender
9.4% (103.5)   [uhci_hcd:usb5, eth1, i915] <interrupt>
8.6% ( 94.5)D  chromium-browse
4.4% ( 48.8)   compiz
3.8% ( 41.5)   alsa-sink
3.4% ( 37.7)   icecast
0.6% (  6.1)   Xorg
0.5% (  6.0)   nginx
0.5% (  5.1)   [Function call interrupts] <kernel IPI>
0.5% (  5.0)   syndaemon
0.4% (  4.1)   [ahci] <interrupt>
0.1% (  1.0)   [hda_intel] <interrupt>