[Qemu-devel] Disable PS/2 mouse

[Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Hi,

is there any way to disable the PS/2 mouse emulation from command line?

BR,
Peter

Re: [Qemu-devel] Disable PS/2 mouse

[Markus Armbruster]

Peter Lieven <pl@dlh.net> writes:

> Hi,
>
> is there any way to disable the PS/2 mouse emulation from command line?

Judging from pc_basic_device_init() and i8042_initfn(): I don't think
so, sorry.

Re: [Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Markus Armbruster wrote:
> Peter Lieven <pl@dlh.net> writes:
>
>   
>> Hi,
>>
>> is there any way to disable the PS/2 mouse emulation from command line?
>>     
>
> Judging from pc_basic_device_init() and i8042_initfn(): I don't think
> so, sorry.
>
>   
would it be difficult to implement?

Re: [Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Markus Armbruster wrote:
> Peter Lieven <pl@dlh.net> writes:
>
>   
>> Hi,
>>
>> is there any way to disable the PS/2 mouse emulation from command line?
>>     
>
> Judging from pc_basic_device_init() and i8042_initfn(): I don't think
> so, sorry.
>
>
>   
background:

with the ps/2 mouse there are always problems with pointer 
synchronization. so i generally use
usb tablet device emulation. BUT. usb emulation is resource intensive. i 
have a testcase with 64
VMs on a dual quadcore xeon and usb alone almost uses the resources of 2 
cpus. so i decided
to introduce an option for 'console-only' vms. but in that case i would 
like to have ps/2 mouse
also disabled in case someone has the wrong option and complains than 
that his mouse
is unsynchronized. so 'console-only' should be no mouse at all.

Re: [Qemu-devel] Disable PS/2 mouse

[Mark Cave-Ayland]

Peter Lieven wrote:

> background:
> 
> with the ps/2 mouse there are always problems with pointer 
> synchronization.

Yeah, we have that here on one of our WinNT VMs. The quick solution we 
found was to install VNC Server on NT and set up everyone to connect to 
that rather than to the physical Qemu/KVM VNC framebuffer. It may not be 
completely optimal, but it at least solves the synchronised mouse 
pointer issue which was the major complaint we were getting from our users.


HTH,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs

Re: [Qemu-devel] Disable PS/2 mouse

[Gerd Hoffmann]

   Hi,

> BUT. usb emulation is resource intensive.

Update qemu.  Fixed in 0.12.4 and unstable.

cheers,
   Gerd

Re: [Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Gerd Hoffmann wrote:
>   Hi,
>
>> BUT. usb emulation is resource intensive.
>
> Update qemu.  Fixed in 0.12.4 and unstable.
thanks for this update. i think my experience came from 0.12.3
i will verify this
>
> cheers,
>   Gerd
>
>
>

Re: [Qemu-devel] Disable PS/2 mouse

[Markus Armbruster]

Peter Lieven <pl@dlh.net> writes:

> Markus Armbruster wrote:
>> Peter Lieven <pl@dlh.net> writes:
>>
>>   
>>> Hi,
>>>
>>> is there any way to disable the PS/2 mouse emulation from command line?
>>>     
>>
>> Judging from pc_basic_device_init() and i8042_initfn(): I don't think
>> so, sorry.
>>
>>   
> would it be difficult to implement?

I don't know.

Re: [Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Gerd Hoffmann wrote:
>   Hi,
>
>> BUT. usb emulation is resource intensive.
>
> Update qemu.  Fixed in 0.12.4 and unstable.
hi gerd,

with 0.12.4 it is still the case that a total idle vm takes about 6-8% 
of a 2.4GHz Xeon Core.

see: http://dev.cs1.dlh.net/usb-on-off.png

until approx 13.00 cet its with -usb -usbdevice tablet and after the 
reboot only with
the ps/2 mouse.

i'm fine generally not using the usb emulation for console only guest 
systems, but in that
case I would like to disable ps/2 mouse as well.

br,
peter

>
> cheers,
>   Gerd
>
>
>


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Peter Lieven

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Re: [Qemu-devel] Disable PS/2 mouse

[Gerd Hoffmann]

   Hi,

> with 0.12.4 it is still the case that a total idle vm takes about 6-8%
> of a 2.4GHz Xeon Core.

I see that order of magitude too, no matter whenever usb is on or off.
With older qemu and usbtablet it used to be up to 25%.

cheers,
   Gerd

Re: [Qemu-devel] Disable PS/2 mouse

[Dor Laor]

On 06/09/2010 05:35 PM, Gerd Hoffmann wrote:
>   Hi,
>
>> with 0.12.4 it is still the case that a total idle vm takes about 6-8%
>> of a 2.4GHz Xeon Core.
>
> I see that order of magitude too, no matter whenever usb is on or off.
> With older qemu and usbtablet it used to be up to 25%.

Is it possible to dynamically control the refresh internally within qemu 
so VMs without a connected VNC client will have rare refreshes or no 
refresh at all? I hope it's not the OS who polls it.

>
> cheers,
> Gerd
>
>

Re: [Qemu-devel] Disable PS/2 mouse

[Gerd Hoffmann]

On 06/10/2010 09:12 AM, Dor Laor wrote:
> On 06/09/2010 05:35 PM, Gerd Hoffmann wrote:
>> Hi,
>>
>>> with 0.12.4 it is still the case that a total idle vm takes about 6-8%
>>> of a 2.4GHz Xeon Core.
>>
>> I see that order of magitude too, no matter whenever usb is on or off.
>> With older qemu and usbtablet it used to be up to 25%.
>
> Is it possible to dynamically control the refresh internally within qemu
> so VMs without a connected VNC client will have rare refreshes or no
> refresh at all? I hope it's not the OS who polls it.

vnc/vga or usb tablet?

For the vga it happens already, with no vnc client connected vnc zaps 
the refresh timer and stops calling vga_hw_update(), thus vga stops 
doing framebuffer dirty tracking too.

For usb hid devices:  No idea how they work and whenever we can put them 
into sleep somehow (with/without guest cooperation).

cheers,
   Gerd

Re: [Qemu-devel] Disable PS/2 mouse

[Peter Lieven]

Gerd Hoffmann wrote:
> On 06/10/2010 09:12 AM, Dor Laor wrote:
>> On 06/09/2010 05:35 PM, Gerd Hoffmann wrote:
>>> Hi,
>>>
>>>> with 0.12.4 it is still the case that a total idle vm takes about 6-8%
>>>> of a 2.4GHz Xeon Core.
>>>
>>> I see that order of magitude too, no matter whenever usb is on or off.
>>> With older qemu and usbtablet it used to be up to 25%.
>>
>> Is it possible to dynamically control the refresh internally within qemu
>> so VMs without a connected VNC client will have rare refreshes or no
>> refresh at all? I hope it's not the OS who polls it.
>
> vnc/vga or usb tablet?
>
> For the vga it happens already, with no vnc client connected vnc zaps 
> the refresh timer and stops calling vga_hw_update(), thus vga stops 
> doing framebuffer dirty tracking too.
>
> For usb hid devices:  No idea how they work and whenever we can put 
> them into sleep somehow (with/without guest cooperation).
is it the emulated bus or the tablet device that is generating the load?


>
> cheers,
>   Gerd
>
>

Re: [Qemu-devel] Disable PS/2 mouse

[Paul Brook]

> For usb hid devices:  No idea how they work and whenever we can put them
> into sleep somehow (with/without guest cooperation).

The issue with USB is that it is (by design) a polled system. The UHCI adapter 
has to wakeup every 1ms to read transfer descriptors from guest RAM.
Until recently there was a bug in the UHCI emulation that would wake the guest 
even if the tablet NACKed the poll.

See http://lists.nongnu.org/archive/html/qemu-devel/2010-04/msg00150.html


USB does support "autosuspend". This allows a guest to put a device to sleep, 
and have it wake up when something interesting happens.  In theory this 
includes HID devices. However I believe linux disables it because there's so 
much broken hardware out there that implements it incorrectly.  I suspect qemu 
does not currently implement this feature either.

Paul