Dear VNC users,
I have set up VNC for use on some UNIX and Windows hosts, and while the X
version of the server works well, the Windows server appears extremely
slow or does not update the screen correctly. I have a sneaking feeling
that this might be a common problem, but the documentation seems to imply
that usable performance is achievable with WinVNC on a 10 megabit network,
hence my enquiry...
I am trying to use VNC to control a Windows 95 host from my X workstation.
I am using the most recent version of the WinVNC and UNIX VNC software
from the VNC WWW site. I installed the binary WinVNC distribution as
service on the Windows 95 host, and I compiled the VNC viewer from the
UNIX source code on the Linux PC where I wish to use the viewer. My X
display is local on the PC. The Windows host is a 200 MHz pentium
processor and has Windows 95 installed. The two hosts are connected via 10
megabit ethernet and there is little or no other data passing over the
network.
With the default configuration of WinVNC, it feels very fast (at least
insofar as the remote mouse pointer tracks the local pointer very closely)
but in most cases, nothing gets drawn on the screen except where the mouse
pointer moves. As I move the mouse around the screen it leaves a trail of
correct display, but aside from that nothing is ever drawn to the screen.
(On the monitor attached to the windows box everything appears as normal,
of course). For example, if I boot Windows then double click on the "My
Computer" icon, the display as seen in the VNC viewer does not change.
However if I move the mouse from side to side across the screen, I can
"uncover" the window that was opened. I have tried various programs and
all seem to be affected by this problem with the exception of the WinVNC
configuration tool, which appears to work somewhat better (although there
was still some screen corruption). The only other exception is at the
moment when I execute the VNC viewer, at which time a complete correct
copy of the screen is displayed.
The curious thing is that even though nothing seems to be getting drawn on
the VNC viewer, the host still displays much slower than normal, as though
the screen is being transmitted via the network. For example after
clicking on the Start button, it takes a moment for the start menu to
appear where normally it would appear straight away. I assume the delay is
transmission of the image before it is drawn on the local screen - yet
nothing appears on the VNC viewer.
It does not seem to be a case of the image being transmitted before the
screen is updated, since if the screen is corrupt behind a window being
opened, for example, it remains in that state.
Turning on the "update whole screen" option solves the problem, but makes
the system so extremely slow that it is barely usable. It even makes the
computer run very slowly when the screen is not being updated; programs
take about 5 times longer to load than is normal, and it takes about 5
seconds to display a drop down menu, for example. Although another curious
fact is that when this is happening, there is only minimal network traffic
coming from the windows machine - so obviously the performance bottleneck
is not associated with the network, but with some kind of processing being
done on the windows host.
I have tried 8- and 16-bit screens, two different graphics cards, and
various combinations of WinVNC options without observing any improvement.
Any advice, either to the effect that what I observe is normal, or else
what to do about it, would be much appreciated.
--
Mario Becroft <[EMAIL PROTECTED]> - http://gem.win.co.nz/mb/
68HC08 support site - http://www.hc08.net/
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