Re: [gtk-vnc-devel] [PATCH 0/7] Optimizations for high-latency X connections

[Anthony Liguori <anthony codemonkey ws>]

Federico Mena Quintero wrote:
> Hi, everyone,
>
> I mentioned in #virt a few weeks ago that I was working on making
> gtk-vnc be nominally as fast as TightVNC.  This came out from an
> Important Customer(tm) who wanted to use virt-viewer, but who found it
> to be too slow.
>
> It turns out that they were on a crazy setup with a high-latency remote
> X connection.  My patches implement some tricks from TightVNC to handle
> such connections:
>   

Can I ask, why in the world is your Important Customer(tm) forwarding 
gtk-vnc over SSH via X instead of doing VNC over X?  That would solve 
all of these problems.

Regards,

Anthony Liguori

> - Request backing store from the X server so we'll hopefully be asked to
> repaint less.
>
> - Compress pointer motion events so both the VNC and X servers can keep
> up.
>
> Finally, I made some things closer to TightVNC itself:
>
> - Specify the supported VNC encodings in the same order as TightVNC.
> Its ordering actually makes a lot of sense; gtk-vnc's didn't seem as
> good from looking at protocol traces with Wireshark.
>
> - Add support for LastRect encoding.  This lets the VNC server send the
> stream of Tight rectangles plus and end-marker, without having to
> compute the actual number of rectangles in advance.
>
> Finally, two extra patches:
>
> - Daniel Berrange's patch from Fedora to avoid requesting framebuffer
> updates when we don't need them.
>
> - Enable local_pointer by default to make aiming easier.  Otherwise we
> have to wait for both VNC and X to repaint before the user will see
> where he is about to click.  This makes things much more usable on
> high-latency X connections.
>
> I'm not horribly happy with just making local_pointer=TRUE; it would be
> better to enable it by default, but use a "dot" cursor like TightVNC
> instead of the normal arrow.
>
> Anyway, I hope this helps.  The next set of patches I submit will be for
> a little tool to get predictable VNC output for profiling purposes.
>
> Federico Mena Quintero (7):
>   Specify supported encodings in the same order as TightVNC
>   Add support for LastRect encoding
>   Debug pointer events
>   Compress motion events to the VNC connection can keep up
>   Use X window backing store for the VNC window
>   Fedora patch: avoid repainting for non-framebuffer requests
>   Enable local_pointer by default to make aiming easy on high-latency X
>     connections
>
>  ChangeLog        |   53 +++++++++++++++++++++
>  src/gvnc.c       |   16 +++++-
>  src/gvnc.h       |    1 +
>  src/vncdisplay.c |  138 +++++++++++++++++++++++++++++++++++++++++++++++-------
>  4 files changed, 188 insertions(+), 20 deletions(-)
>
>   Federico
>
>
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