Xvnc - CPU Hog!

Fri, 20 Nov 1998 10:23:16 +0000

I seem to remember several years ago discovering that SUN Openwindows used 10%
of CPU when doing nothing. It was then we decided top use remote X servers
running on PCs. We still run XVNC on a separate machine from the one doing the
work. The point I'm trying to make is that it could be the X part of VNC that is
using the CPU time.

Dave Addison
Smiths Industries
Cheltenham
Tel: +44-1242-678555
Fax: +44-1242-661360,,,2440

-----Original Message-----
From:   Charles_T_Kennedy "at" tst.tracor.com (Charles T Kennedy) 
Sent:   Wednesday, November 18, 1998 11:31 AM
To:     vnc-list "at" orl.co.uk
Subject:        Xvnc - CPU Hog!

Greetings,

VNC is one great product, however my system administrators are 
complaining about it being a CPU hog.  They say it has eaten up to 50% 
of the CPU time for extended periods of time.  On one specific 
occasion, the user was notified and he closed all the windows he had 
open in his vnc session, and Xvnc was still using 50% of the CPU time 
(according to "top").

On an everyday basis, I have noticed that Xvnc routinely requires 
around 10% when opening and closing windows and the like.  And it 
easily goes up to 25% or higher when scrolling through a long text 
file.

Currently, there are only three of us using vnc on a regular basis, 
however we expect to have quite a few using either vnc or an 
x-terminal emulator within the next few weeks.  If 20 users each 
require a mere 5% of the CPU time just for Xvnc, then we have a real 
problem!  Is this issue being addressed?  Are there some setup options 
we can use to reduce the load on the Xvnc host?

For the record, we are running Xvnc version 3.3.2r2, CDE under 
Solaris, and "uname -a" returns the following information:

  SunOS sunkist 5.5 Generic_103093-12 sun4m sparc SUNW,SPARCstation-20

We have set the background to solid, and reduced the number of colors 
used by CDE itself to 4.  We are running VNCviewer 3.3.2R9 under Win95 
on Pentium 100 or faster computers with a T1 connection to the Sun.

The following comes from my latest vnc logfile:

  18/11/98 08:31:28 Pixel format for client xxx.xx.xx.xxx:
  18/11/98 08:31:28   32 bpp, depth 24, little endian
  18/11/98 08:31:28   true colour: max r 255 g 255 b 255, shift r 0 g 
  8 b 16
  18/11/98 08:31:28 Using hextile encoding for client xxx.xx.xx.xxx
  18/11/98 08:31:28 rfbProcessClientNormalMessage: ignoring unknown 
  encoding type 3

VNCviewer reports the following "connection info":

  Connected to: ckenned's X desktop (xxx:1)
  Host: xxx.xxx.xxx port: 5901

  Desktop geometry: 1016 x 712 x 24
  Using depth: 24
  Current protocol version: 3.3

  Current keyboard name: 00000409

Note that the geometry is set to 1016x712 on purpose--to fill the 
whole Win95 screen without covering the task bar.  My display is set 
to 1024x768 HiColor (16 bit).

                                   Thanks,
                                   Charles Kennedy

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