Rick, As mentioned by others, disabling polling can reduce CPU usage on the server (host) system significantly. That is certainly the first thing to check.
However, CPU time is also used to encode the updates. For fast networks, like 100MB/s, hextile has a low CPU utilization profile, but the raw encoding uses even less CPU time. Of course, it places higher demands on the network card and uses much more raw bandwidth. You can select the desired encoding in the vncviewer options dialog before connecting. In your environment, I would avoid zlib, zlibhex and tight, because they use more CPU time to generate less network traffic. Finally, WinVNC.exe must copy screen data from the video RAM back into main memory to detect changes. The speed of this operation probably depends on the video card and the video driver. Are these up-to-date? Further comments below. > Date: Wed, 14 Nov 2001 09:14:18 -0500 > From: "Watson, Rick" <[EMAIL PROTECTED]> > Subject: VNC system resources useage on WIN2K > > We do public opinion surveys and use VNC to monitor the surveyor to make > sure their work is accurate. We had switched from M'soft SMS to VNC because > SMS was way too slow. We did that several years ago when our primary > application was DOS based. Now that we've upgraded to Windows software, VNC > has a serious impact on the speed of the interviewing software. I've tried > AT&T, Tridaic, and now TightVNC. It's not so much VNC, but the system > resources diverted to VNC on the client that causes the application to bog > down completely. The application uses Visual Basic. I'm sure the problem is > with machine resources and not network speed, we are on a 100MB line and > changing encoding/compression levels hasn't had a major impact. The machine > being viewed can have as much as 50% of their processor time used by VNC. > The clients are PII 450, with 128MB RAM. > > Does anyone have any ideas how to negate the impact on the client machine? > Is one version of VNC better at this than others? This is a matter of opinion of course, but I think you will make more progress in the area of CPU utilization by disabling polling and using raw or hextile that with switching VNC versions. > Also, for TightVNC is > there a way of using command switches to turn off CopyRect encoding and make > Display-View Only the default? It seems those have to be set each time. I think all versions of vncviewer.exe accept the "/viewonly" command line switch. Also, if you save the connection settings to a configuration file, you can use "/config file" to load those when starting the viewer. The latest source code for vncviewer.exe from www.developvnc.org supports a command line switch "/disableCopyRect". Currently the only way to get a *binary* for that from Tridia is to download TridiaVNC Pro: http://www.tridiavncpro.com/ You didn't think I was going to end this email without a shameless plug for our product did you? > > TIA, > > Rick Watson -- Brian ---------------------------------------------------------------------------- TridiaVNC Pro: finally, affordable remote control. http://www.TridiaVNCPro.com/ ---------------------------------------------------------------------------- Tridia's Mission: To always exceed our customers' expectations by providing the absolute best software products backed by outstanding technical support and customer service. Please let us know how we are doing: brian . blevins @ tridia.com or ceo-hotline @ tridia.com. --------------------------------------------------------------------- To unsubscribe, mail [EMAIL PROTECTED] with the line: 'unsubscribe vnc-list' in the message BODY See also: http://www.uk.research.att.com/vnc/intouch.html ---------------------------------------------------------------------
