WinVNC & NT: 100% CPU utilization

James [Wez] Weatherall jnw "at"
Thu, 26 Mar 1998 09:54:34 +0000

On Wed, 25 Mar 1998, dave w capella wrote:

> The funny thing is (thankfully), my main linux server, with 3 VNC daemons
> running, doesn't show any load at all with 3 or 4 clients connected.

The VNC server on Unix (Xvnc), is a custom-modified X server.  This means
that we have access to all operations in it that affect the display.  The
Windows version, however, has to hook into the message queues of Windows
on the desktop and uses these to get hints as to what has changed.  The
result is that WinVNC must check to ensure that regions it thinks may have
changed _have_ actually changed (otherwise, a large number of updates
would be redundant).  Xvnc doesn't have to do this, so it's CPU usage is
correspondingly lower.


James "Wez" Weatherall
Olivetti & Oracle Research Laboratory, Cambridge, UK.
Tel : Work - 343000