Re: [VirtualGL-Users] Single application runs very slow with VirtualGL/TurboVNC while others run fine

[Reiner R. <rot...@at...>]

Hi Dan,

thanks for your quick reply and your very useful suggestions!

On Thursday 24 April 2008 10:59:09 am Dan Phung wrote:
> > - Is there a way to further debug a VirtualGL session?
>
> try these:
> vglrun -h
>    +/-tr     : Enable/disable function call tracing (generates a lot
> of output)
>    +/-v      : Enable/disable verbose VirtualGL messages

I will give it a try.

> > - What are the most prominent sources of error why this one
> > application is
> > still slow?
>
> do you know if network or cpu was the bottleneck?

We monitored both network and cpu usage during our tests and the network was 
not the limiting factor in the LAN tests but it is not clear, if the network 
is the problem in the lower bandwith connection.

Btw. what is worse, high latency (6-8ms) or limited bandwidth regarding smooth 
display?

Overall one CPU gets stressed to the max during rotation/zooming of objects. 
But I don't know if this is the root cause for slow/laggy display.

>
> > - Are there any general tipps to further increase overall performance?
> > - Is there any practical experience how many users may use VirtualGL
> > simultanously?
>
> this is a good source of info:
> http://www.virtualgl.org/pmwiki/uploads/About/vglperf21.pdf

The testresults are very interesting. Thanks for the link!

I think a high framerate is key to our issue. The users have to rotate objects 
in order to visualize details in pre/post processing and they are used to 
smooth rotations/zooms.

They wish that comfort decreases as little as possible when they work from 
remote.

For example if the display lags, it is difficult to precisely move objects 
with the mouse. With lots of lags the object still rotates when the mouse 
input stopped. So the users need to undo wiggly movements.


Best regards,
Reiner