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RE: [Xen-devel] Re: improving VNC performance

To: "Tim Deegan" <tim@xxxxxxx>, "Paolo Bonzini" <pbonzini@xxxxxxxxxx>
Subject: RE: [Xen-devel] Re: improving VNC performance
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Tue, 26 Jul 2011 20:52:12 +1000
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Thread-topic: [Xen-devel] Re: improving VNC performance
> 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
> >
> > Block moves are accelerated if you use the Cirrus VGA.  Nothing else
> > though. :)
> Actually we found that it's faster to turn that acceleration off,
> 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.


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