[Spice-devel] Unfair comparisons with RDP

[John A. Sullivan III]

On Sat, 2011-06-25 at 15:34 +0200, Alon Levy wrote:
> On Fri, Jun 24, 2011 at 09:36:26PM -0400, John A. Sullivan III wrote:
> > Hello, all. Another question to be answered only if there is time.  As
> > we put SPICE head to head with the TSPlus implementation of RDP, SPICE
> > seems to be coming up a bit short and I expect it is somewhat unfairly
> > so.  It appears that RDP starts painting the screen sooner that SPICE
> > does and so it appears more responsive even if it takes longer to finish
> > painting the page than SPICE does.
> > 
> > Why is that? More importantly, is there a way to tweak SPICE to mitigate
> > this effect or is there something in the works to make the initial delay
> > less pronounced? Thanks - John
> 
> What exactly is the test? what do you mean starting / stopping, does the
> time include the launch of spicec or spicy and the connection?
> 
> If it includes the connection time perhaps this is a result of the insane
> bandwidth calculation we use, sending a very large packet of zeros at
> connection initiation.
<snip>
Sorry for the lack of clarity.  I'm not referring to start up time.
That IS noticeably slower but I think the bandwidth detection is a
critical feature and differentiator for SPICE.

I'm referring to actual usage of the desktop.  All actions from
scrolling a window to clicking a slider to opening a hyperlink, even
typing very quickly seem slower to start in SPICE than in RDP. The
difference is only a fraction of a second but it is humanly perceptible
and gives the impression of laggard performance.

On large graphic refreshes of the screen, it seems clear that SPICE
finishes painting the screen faster than RDP even if it appears to start
later - it comes from behind like the Boston Red Sox (sorry for the
American sports humor!) but appears to the user who is more concerned
about when it starts to be slower.  When changing only small parts of
the screen such as typing, there isn't the opportunity to "come from
behind" and thus SPICE is being rated as slower than RDP, i.e, for
everyday usage, not start up.  Thanks - John