KVM power usage - high wakeup rates

["Haydn Solomon" <haydn.solomon@gmail.com>]

Hi List,

When testing power usage of a windows xp guest using powertop utility,
I'm noticing high wakeup rates. The following is the output of
powertop for an idle windows xp guest.


==============================
===========================
Wakeups-from-idle per second : 2716.6   interval: 10.0s
no ACPI power usage estimate available

Top causes for wakeups:
  52.4% (2434.4)   qemu-system-x86 : sys_timer_settime (posix_timer_fn)
  21.5% (996.7)   qemu-system-x86 : __kvm_migrate_pit_timer (pit_timer_fn)
  15.0% (697.4)       <interrupt> : extra timer interrupt
   4.9% (227.6)      <kernel IPI> : Rescheduling interrupts
   1.6% ( 72.9)   USB device  6-2 : Optical USB Mouse (Logitech)
   1.3% ( 61.7)       <interrupt> : nvidia
   1.3% ( 59.0)       <interrupt> : uhci_hcd:usb4, uhci_hcd:usb6, HDA Intel
===================================================================

I'm getting similar values when running a Fedora 9 guest.

My host is running F9. Details of my /proc/cpuinfo :

processor    : 1
vendor_id    : GenuineIntel
cpu family    : 6
model        : 15
model name    : Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz
stepping    : 10
cpu MHz        : 2201.000
cache size    : 4096 KB
physical id    : 0
siblings    : 2
core id        : 1
cpu cores    : 2
fpu        : yes
fpu_exception    : yes
cpuid level    : 10
wp        : yes
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni monitor
ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm ida
bogomips    : 4387.73
clflush size    : 64
cache_alignment    : 64
address sizes    : 36 bits physical, 48 bits virtual
power management:

The linux image I'm running is Linux localhost.localdomain
2.6.25.4-30.fc9.x86_64 #1 SMP Wed May 21 17:34:18 EDT 2008 x86_64
x86_64 x86_64 GNU/Linux

I'm starting my vm using the following command:

/usr/local/kvm/bin/qemu-system-x86_64 \
-hda windowsxp.img \
-m 650 \
-localtime \
-net user \
-net nic,model=e1000 \
-smb /home/hsolomon \
-std-vga \
-soundhw all \
-usb \
-usbdevice tablet \
-name StandardPC-NAT &

Thanks

Haydn