Re: KVM power usage - high wakeup rates

[Anthony Liguori <anthony@codemonkey.ws>]

Haydn Solomon wrote:
> If I'm just using SDL, does usb tablet provide any benefit?
>   

You don't have to do explicit key grab.

Regards,

Anthony Liguori

> On Thu, Jun 19, 2008 at 2:34 PM, Anthony Liguori <anthony@codemonkey.ws> wrote:
>   
>> Haydn Solomon wrote:
>>     
>>> 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 &
>>>
>>>       
>> USB tablet polls a lot.  You'll probably see far less wake ups if you don't
>> use the tablet.
>>
>> With the default options, my idle winxp guest causes about 550 wakeups/sec
>> which is pretty close to what I'd expect.  I don't think you'll get much
>> better than that without using a dynticks guest.
>>
>> Regards,
>>
>> Anthony Liguori
>>
>>     
>>> Thanks
>>>
>>> Haydn
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>>>       
>>