x11vnc and vncviewer for classroom

James Cameron quozl at laptop.org
Sat Nov 22 19:58:28 EST 2008

On Sat, Nov 22, 2008 at 08:52:12PM +0530, Arjun Sarwal wrote:
> I was wondering if someone could comment on the performance when I
> have about 30 X0s connected to the same ?

Maybe a refresh once every 15 seconds?

I've just tried this.  Ran x11vnc -viewonly -shared -forever on a Debian
desktop, 1600x1200, and used krdc on a couple of XOs.  In high quality
mode, krdc repaints took up to two seconds when a major screen change
happened.  But in low quality mode the repaint was about a fifth of a
second.  So I have not reproduced your "once about every one second".

You are using point to point networking.  As long as the bandwidth of
the shared medium (the RF) is not hit, then it should continue to scale.
The bandwidth depends on x11vnc options chosen, and on what changes are
made to the teaching image.  There are ways to specify to x11vnc what
bandwidth to use for the clients.  You should only need to add the right
option to ensure you do not fill the RF bandwidth.  See the -speeds
option.  4619 lines of man page.  Wow.

There's an opportunity here to look for ways to multicast VNC updates.
I'm not sure of what is available for this.

James Cameron    mailto:quozl at us.netrek.org     http://quozl.netrek.org/

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