SSH Compression - Block Deduplication

[Morty Abzug]

On Tue, Sep 13, 2011 at 09:28:24AM -0700, Matt Olson wrote:

> It's the only GUI implementation I know of that actually splits
> display from the application in a client/server model; which allows
> you to work with applications from multiple hosts seemlessly in a
> single window manager.

I've read that recent application sharing implementations from both
Citrix and Microsoft have incorporated this feature.

> The approach of possibly improving gzip/LZ77 performance still semms
> like it might be worth while and have value beyond X11 tunneling.

FWIW, I would also love to see performance improvements for ssh
tunneling of raw X11.  I'm recommending x11vnc (and note
tightvncviewer's -via option) as a workaround, not as a solution.

While a compression approach would certain help, please note that
there are a lot of X11 performance problems that cannot be solved with
compression.  For example, some applications display a whole bunch of
status updates at startup.  Those updates display in seconds to a
local display, but can take hours when played over a slow WAN link.
Compression might help, but realistically, not by more than a factor
of 10 or so.  The tight VNC approach of implementing a virtual
framebuffer and sending compressed updates only as needed effectively
eliminates the status updates altogether.  If that can somehow be
implemented transparently via openssh, it would be a big win.
[Although maybe this is more easily done in X11 itself.]

- Morty