[Spice-devel] Unfair comparisons with RDP

[Alon Levy]

On Fri, Jul 01, 2011 at 03:00:32PM +0200, Gianluca Cecchi wrote:
> On Fri, Jul 1, 2011 at 1:04 PM, John A. Sullivan III  wrote:
> > Interesting observation. That is true; we did not create separate VM
> > definitions for SPICE and TSPlus thus the TSPlus environment is using
> > the QXL driver.  Would we expect that to have any "supercharging" effect
> > on RDP?
> >
> >
> 
> Probably not, because afaik (that is not so much ;-) Remote Desktop
> (and probably tsplus too) works at the GDI call level, so it should
> not depend so much on video adapter/video driver...
> It was simply a question that arose analysing how to correctly
> replicate comparisons...
> Coming back to the test case and these operations:
> 
> rdp
> 17:             display desktop, i.e., minimize all open applications
> 42:             Paint existing LibreOffice document, i.e., restore from minimize
> 
> spice
> 61:             display desktop, i.e., minimize all open applications
> 92:             Paint existing LibreOffice document, i.e., restore from minimize
> 
> I think they are GDI ones, so that naturally when using rdp they are
> executed locally on client desktop (only the gdi directives are sent),
> while in spice (raster?) they will be network intensive (from a slow
spice implements a driver, which implements a large part of the gdi api. So any
operation that it doesn't implement is done via the windows gdi software rendering
and the result given to the driver (which is spice) as an image.

So in cases where the specific operations are all implemented by the driver the
performance should be identical. In other cases spice will be suboptimal, since
it will send the image and not the operation. In both cases the rendering should
be correct.

> link point of view).
> So probably an optimized rdp could never be beaten on too slow links?
> 
> So my question is: could it be that instead of say spice vs tsplus in
> general, we ought to go in determining what is the minimum necessary
> bandwith to give the final user an acceptable experience (need to
> define "acceptable" ;-) ?
> 
> Or, if I'm not wrong, as pcoip incorporates in some way both rdp and
> raster capabilities so that it is able to "automatically" determine
> what to use, the right way should be to do something similar for
> spice?
> 
> Gianluca