[fedora-virt] Different cpu usage between Fedora and SL6 guests - SOLVED

[Dor Laor]

On 07/18/2012 10:12 PM, Orion Poplawski wrote:
> On 07/18/2012 11:04 AM, Cole Robinson wrote:
>> On 07/18/2012 11:17 AM, Orion Poplawski wrote:
>>> On 07/17/2012 04:50 PM, Orion Poplawski wrote:
>>>> While staring at top on my SL6 kvm server waiting for it to crash, I
>>>> noticed
>>>> that my idle Fedora kvm guests appear to be consuming between 8-12%
>>>> cpu while
>>>> my idle SL6 guests appear to be consuming between 0.3-2% cpu as
>>>> shown in the
>>>> qemu-kvm processes in top.  In fact I have a Fedora 17 instance
>>>> running now
>>>> with nothing but kernel processes and the qemu-kvm process still
>>>> shows it
>>>> using 7-8% cpu.
>>>>
>>>> Does anyone have any insight as to why this would be the case?
>>>>
>>>
>>>   It appears that toggling the Autosuspend for USB device QEMU USB
>>> Tablet [QEMU
>>> 0.12.1] tunable has a big effect and brings it in line with SL6.
>>>
>>> SL6:
>>> usb 1-1: Product: QEMU USB Tablet
>>> input: QEMU 0.12.1 QEMU USB Tablet as
>>> /devices/pci0000:00/0000:00:01.2/usb1/1-1/1-1:1.0/input/input4
>>> generic-usb 0003:0627:0001.0001: input,hidraw0: USB HID v0.01 Pointer
>>> [QEMU
>>> 0.12.1 QEMU USB Tablet] on usb-0000:00:01.2-1/input0
>>>
>>> # cat /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1/power/autosuspend
>>> 2
>>> # cat  /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1/power/level
>>> auto
>>>
>>> F17:
>>> [    3.015642] usb 1-1: Product: QEMU USB Tablet
>>> [    3.117125] input: QEMU 0.12.1 QEMU USB Tablet as
>>> /devices/pci0000:00/0000:00:01.2/usb1/1-1/1-1:1.0/input/input3
>>> [    3.117827] generic-usb 0003:0627:0001.0001: input,hidraw0: USB
>>> HID v0.01
>>> Pointer [QEMU 0.12.1 QEMU USB Tablet] on usb-0000:00:01.2-1/input0
>>>
>>> # cat /sys/devices/pci0000:00/0000:00:01.2/usb1/power/autosuspend
>>> 2
>>> # cat  /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1/power/level
>>> on
>>>
>>> So it appears that SL6 is setting to auto automatically, but Fedora
>>> is not.  I
>>> wonder why.
>>>
>>
>> Hmm, could you please open a bug for that? I guess against F17 qemu
>> for now,
>> might be kernel or udev though. I think this is a regression from
>> previous
>> releases, tablet autosuspend is supposed to work out of the box.
>>
>> Thanks,
>> Cole
>>
>
> Filed against udev since that is where it was fixed in EL6.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=841368

Gerd, any idea why autosuspend isn't working in F17 guest?

Thanks,
Dor