[cw-discuss] Office2003 running on remote Xvnc causes extremely large X traffic

[Nikita V. Youshchenko]

Hello.

I've faced the followinf issue.

We have a setup that highly uses Xvnc to provide user sessions that migrate 
between physical terminals.

There is a host (Xen domain, if that's important) where Xvnc processes run.

There is anouther host (another Xen domain, currently hosted on other 
physical machine) where we try to run microsoft office apps using 
cxoffice.

Network is gigabit, iperf measures >500 Mpbs between hosts.

So cxoffice apps run with $DISPLAY set to remote hosts. No ssh forwarding - 
just plain X connection.

Office2000 apps run without major problems.

However, office2003 apps run extremely slow on most (although not all) 
documents. Page redraw may take >30 seconds. Delay between key pressed and 
character appears on the screen may be up to several seconds.

When running to local $DISPLAY, office2003 runs at expected speed.

I've found using tcptrack utility that office2003 apps, when they are slow, 
are creating extremely large traffic on X connection between app and Xvnc 
server: when app is idle (visually doing nothing), traffic may be up to 
600 kilobytes per second, and when app is active (e.g. redrawing a page), 
traffic is up to 20 megabytes per second (not megabits by megabytes) - 
that's even more than traffic of a video player displaying to remote X!

I guess hat huge X traffic is *the* reason of apps being slow.

Any hints why there is such huge X traffic, and how to avoid it?

Nikita Youshchenko,
sysadmin @lvk.cs.msu.su

P.S.
Please CC replies to my e-mail