Hi,

I tried using the Cadence CAD software using
VNC.  This is all in the same department, so
so it should be at ethernet speeds.  If I
start up a vncserver on one sun box, and
connect to it from another sun box, speed is
fine.  If I connect to a sun box from a PC
using Exceed, speed is fine.  If I connect
to a sun box using VNC, but don't use Cadence,
speed is fine.

The only time speed is really slow is when I
use Cadence via a VNC connection from PC to
sun box.  This is really strange, because if
it was a bandwidth problem, it should exhibit
itself when using VNC to connect from sun to
sun.  As well, it should show itself when
using Exceed.

Just for kicks, I Exceeded into a sun box and
VNC'd from the sun box to another sun box.  I
launched Cadence in the 2nd sun box.  Things
were very sluggish.  I then tried launching
Cadence in the 2nd sun box, but as a normal
X client to the X server on the 1st sunbox.
Exceed still acts as the link from PC to the
1st sun box.  It was somewhat slow, but not
nearly as slow as the combining Exceed with
VNC.

I thought the bottleneck was conversion from
Cadence's pseudocolor to the PC's true color.
To test this, I creatd a 24-bit true color
VNC server running on Sun.  This server would
emulate a PC.  Within this server, I launched
a viewer that connects to a 2nd remote
pseudocolor VNC server.  Speed of Cadence was
fine, as long as I connect to the 24-bit VNC
server from a sun box.  Speed was terrible if
I try from a PC.

One thing I did notice when combining Exceed
with VNC is this.  Even though the local cursor
(a tiny dot) is moved quickly to another location,
the "other" cursor (the one which changes shape,
presumably the "remote" cursor) lags behind and
flickers very rapidly.  As if the screen is
undergoing many updates that prevent it from
keeping up with the local cursor.  It almost
seems that the Cadence the application is not
able to get information about the current cursor
location until some lag time has passed.

The only explanation I can think of for this
disparity in speed is that Cadence uses high
level draw/fill commands to the X server to
update the window and buffer certain images.
One example that supports this is the lightning
fast response when switching between views that
show only cell outlines versus cell details.

Anyway, thanks if anyone can comment on this,
or describe their own experience, including any
experiments.

Fred
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