vnc performance AND mailing list format improvement

Fred fma "at"
Sun, 17 Mar 2002 07:15:00 +0000

Sorry for repeating this, but I forgot to change
the #@!!?@@$%! subject line.  (Along these lines,
I've been trying to ask for an improvement in the
format for VNC forum,

Yeah, I forgot to mention, I'm using ADSL, otherwise
I'd say IC layout was definitely out.

I'd like to add something to Evan's remark.  The only
encoding that seems to load the server is tight
encoding.  That encoding is only beneficial if
bandwidth is reduced to that of a 56Kbps modem,
either through heavy network/internet traffic, because
access to your office is crowded, or because you
really have just a 56Kbps modem.  But the overhead
in the compression esnures that you also never get
preformance above that of 56Kbps with compression,
even if the available bandwidth is much greater.
So don't use tight encoding if your have real
effective bandwidth (end to end, not just the
connection to your home).

As I mentioned, whenever you're using tight
encoding, either out of necessity or because
your forgot to switch out of it, layout and interactive
drawing might be impossible unless you have inhuman
patience.   So anytime the server is likely to be loaded
by tight encoding is also the time that you're least
likely to do interactively-intense CAD work.  The
non-interactive-intense graphical stuff might be

For these reasons, I don't anticipate the loading of the
server by VNC (or tightVNC) to be an overly big
issue.  This is just crystal ball gazing, so give it a try.
Install TightVNC, try both types of CAD work and
monitor with "top".  Try with both tight encoding and
hextile.  Then try during busy times and night times.
Thats only a 2x2x2 matrix of possibilities.  You may
come to the same conclusions.  Oh, yeah, you may
try an actual 56kbps modem also, and find that
tight encoding is essential, and that it doesn't differ
that much from tight encoding over ADSL.  In fact,
if the internet is busy enough or the access to your
office is crowded enough, 56kbps may actually be
better (still talking about tight encoding in this case).

Fred Ma
Department of Electronics
Carleton University, Mackenzie Building
1125 Colonel By Drive
Ottawa, Ontario
Canada     K1S 5B6
fma "at"

> Date: Sat, 16 Mar 2002 17:16:14 -0500
> From: Fred <fma "at">
> Subject: Re: vnc performance
> Yep, I've used that configuration over the internet.
> During the night, it might be OK to do IC layout ( I
> mean after everyone has gone to bed and the
> internet is free), but during the day, It's just managable
> to use signal waveform viewers.  Matlab graphing is
> also OK. Drawing software, I don't know, that might
> be a night time thing also.  Note however that during
> the day, I use tightVNC's tight encoding for its
> compression, otherwise I'm not sure what would
> be do-able during the day aside from pure text
> sessions like telnet.
> Fred
> P.S.  For best speed, use the default
> pixel depth of 8-bits.  Some CAD tools
> require pseudocolor on the server, and I'm
> not sure thre is any relation with the 8-bits.
> ==========================================================================
> Date: Fri, 15 Mar 2002 17:02:58 -0600
> From: barnowl "at"
> Subject: Re: vnc performance
> IF you plan on using CAD on a remote desktop you will need one MOHTER of a fast machine connected to a BIG pipe. With VNC Client speed is real not much of an issue as all the client does is reproduce pcitures and send key strokes. The Server does all the work, from doing CAD redraws to stuffing all that desktop imagery down the pipe. In this case teh biggest bottle neck will be the Server though. If you plan on more than one person using it, I would recommend an SMP box a CAD version that can use SMP. For the home ppl you will need at least ADSL to make it even worth working with.
> Evan
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