improving VNC performance

improving VNC performance

[James Harper]

What scope is there for improving VNC performance on HVM machines,
mainly Windows?

It would be really nice to be able to cut&paste (would require a
userspace app), and to fake some accelerator functions (eg block moves).

Thanks

James

Re: improving VNC performance

[Todd Deshane]

On Mon, Jul 25, 2011 at 10:00 PM, James Harper
<james.harper@bendigoit.com.au> wrote:
> What scope is there for improving VNC performance on HVM machines,
> mainly Windows?
>
> It would be really nice to be able to cut&paste (would require a
> userspace app), and to fake some accelerator functions (eg block moves).
>

One alternative could be to use something like Spice (which has copy
and paste and good user experience)
http://spice-space.org/
http://code.google.com/p/spice4xen/

For copy and paste only there are utilities such as:
http://sourceforge.net/projects/synergy2/
http://beyondcopy.sourceforge.net/

It seems that VNC does have some copy and paste ability too
(OpenXenManager and XenCenter implement copy and paste for
XCP/XenServer vnc consoles for example).

More discussion on the topic here:
https://bugs.launchpad.net/qemu/+bug/614958

Thanks,
Todd

Re: improving VNC performance

[Pasi Kärkkäinen]

On Mon, Jul 25, 2011 at 10:22:47PM -0400, Todd Deshane wrote:
> On Mon, Jul 25, 2011 at 10:00 PM, James Harper
> <james.harper@bendigoit.com.au> wrote:
> > What scope is there for improving VNC performance on HVM machines,
> > mainly Windows?
> >
> > It would be really nice to be able to cut&paste (would require a
> > userspace app), and to fake some accelerator functions (eg block moves).
> >
> 
> One alternative could be to use something like Spice (which has copy
> and paste and good user experience)
> http://spice-space.org/
> http://code.google.com/p/spice4xen/
> 
> For copy and paste only there are utilities such as:
> http://sourceforge.net/projects/synergy2/
> http://beyondcopy.sourceforge.net/
> 
> It seems that VNC does have some copy and paste ability too
> (OpenXenManager and XenCenter implement copy and paste for
> XCP/XenServer vnc consoles for example).
> 

Do you know if there's an official VNC extension for copy&paste? 

-- Pasi

> More discussion on the topic here:
> https://bugs.launchpad.net/qemu/+bug/614958
> 
> Thanks,
> Todd
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: improving VNC performance

[James Harper]

> 
> On Mon, Jul 25, 2011 at 10:22:47PM -0400, Todd Deshane wrote:
> > On Mon, Jul 25, 2011 at 10:00 PM, James Harper
> > <james.harper@bendigoit.com.au> wrote:
> > > What scope is there for improving VNC performance on HVM machines,
> > > mainly Windows?
> > >
> > > It would be really nice to be able to cut&paste (would require a
> > > userspace app), and to fake some accelerator functions (eg block moves).
> > >
> >
> > One alternative could be to use something like Spice (which has copy
> > and paste and good user experience)
> > http://spice-space.org/
> > http://code.google.com/p/spice4xen/
> >
> > For copy and paste only there are utilities such as:
> > http://sourceforge.net/projects/synergy2/
> > http://beyondcopy.sourceforge.net/
> >
> > It seems that VNC does have some copy and paste ability too
> > (OpenXenManager and XenCenter implement copy and paste for
> > XCP/XenServer vnc consoles for example).
> >
> 
> Do you know if there's an official VNC extension for copy&paste?
> 

I always assumed that it was part of the core protocol and that it just didn't work under xen because the vnc is happening at the raw framebuffer level rather than at the gdi level...

I was hoping that someone might have already thought about hooking into the gdi level with a driver and bypassing the xen framebuffer and taking over the backend vnc connection that way... on reflection it sounds like something fraught with security holes though :)

James

Re: improving VNC performance

[Paolo Bonzini]

On 07/26/2011 04:00 AM, James Harper wrote:
> It would be really nice to be able to cut&paste (would require a
> userspace app), and to fake some accelerator functions (eg block moves).

Block moves are accelerated if you use the Cirrus VGA.  Nothing else is, 
though. :)

Paolo

Re: Re: improving VNC performance

[Tim Deegan]

At 08:45 +0200 on 26 Jul (1311669952), Paolo Bonzini wrote:
> On 07/26/2011 04:00 AM, James Harper wrote:
> >It would be really nice to be able to cut&paste (would require a
> >userspace app), and to fake some accelerator functions (eg block moves).
> 
> Block moves are accelerated if you use the Cirrus VGA.  Nothing else is, 
> though. :)

Actually we found that it's faster to turn that acceleration off, since
it's not really accelerated --- it'll be a memcpy either in domU or in
qemu, and you might as well skip the (slow, synchronous) emulated
register writes that domU would use to drive the blitter.

IIRC, the Citrix Windows drivers installer sneakily turns acceleration
off on the Cirrus driver's settings. 

Tim.

-- 
Tim Deegan <tim@xen.org>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

Re: Re: improving VNC performance

[Paolo Bonzini]

On 07/26/2011 10:27 AM, Tim Deegan wrote:
> At 08:45 +0200 on 26 Jul (1311669952), Paolo Bonzini wrote:
>> On 07/26/2011 04:00 AM, James Harper wrote:
>>> It would be really nice to be able to cut&paste (would require a
>>> userspace app), and to fake some accelerator functions (eg block moves).
>>
>> Block moves are accelerated if you use the Cirrus VGA.  Nothing else is,
>> though. :)
>
> Actually we found that it's faster to turn that acceleration off, since
> it's not really accelerated --- it'll be a memcpy either in domU or in
> qemu, and you might as well skip the (slow, synchronous) emulated
> register writes that domU would use to drive the blitter.

Yes, it's slower but saves bandwidth.  It depends on your use case.

Paolo

RE: Re: improving VNC performance

[James Harper]

> 
> At 08:45 +0200 on 26 Jul (1311669952), Paolo Bonzini wrote:
> > On 07/26/2011 04:00 AM, James Harper wrote:
> > >It would be really nice to be able to cut&paste (would require a
> > >userspace app), and to fake some accelerator functions (eg block
moves).
> >
> > Block moves are accelerated if you use the Cirrus VGA.  Nothing else
is,
> > though. :)
> 
> Actually we found that it's faster to turn that acceleration off,
since
> it's not really accelerated --- it'll be a memcpy either in domU or in
> qemu, and you might as well skip the (slow, synchronous) emulated
> register writes that domU would use to drive the blitter.
> 
> IIRC, the Citrix Windows drivers installer sneakily turns acceleration
> off on the Cirrus driver's settings.
> 

The sort of acceleration I was referring to would happen on the vnc
client end, eg a window scrolling up might blit the contents of the
window 10 pixels up.

James

Re: improving VNC performance

[Jean Guyader]

On 26 July 2011 03:00, James Harper <james.harper@bendigoit.com.au> wrote:
> What scope is there for improving VNC performance on HVM machines,
> mainly Windows?
>
> It would be really nice to be able to cut&paste (would require a
> userspace app), and to fake some accelerator functions (eg block moves).
>

Switching from a linear framebuffer to a titled framebuffer would help a lot.
We will hit much fewer pages on mouse motion in the dirty bit tracking.

I don't know if the Cirrus supports that.

Jean

Re: improving VNC performance

[Jean Guyader]

On 26 July 2011 09:44, Jean Guyader <jean.guyader@gmail.com> wrote:
> On 26 July 2011 03:00, James Harper <james.harper@bendigoit.com.au> wrote:
>> What scope is there for improving VNC performance on HVM machines,
>> mainly Windows?
>>
>> It would be really nice to be able to cut&paste (would require a
>> userspace app), and to fake some accelerator functions (eg block moves).
>>
>
> Switching from a linear framebuffer to a titled framebuffer would help a lot.
> We will hit much fewer pages on mouse motion in the dirty bit tracking.
>

Sorry typo, I meant tiled.

Jean