[FreeNX-kNX] NX screen refresh performance

[chris at ccburton.com]

"--\[ UxBoD \]--" <uxbod at splatnix.net> wrote on 30/04/2010 15:27:36:

> Hello all,
> 
> I am looking for a little bit of explanation on how the X11 session 
> is delivered to the client; and whether improving the performance of
> the local X11 server would improve the overall experience?
> 
> I notice a real lag of the screen when I resize images or even move 
> windows around the screen.
>

[SNIP]

> 
> Reading one of the NX documents about slow performance it mentions:
> 
> "Upgrading to a more recent version of the X server or trying a 
> different video driver can surely offer a great boost. For example a
> hardware accelerated video card is recommended to obtain the best 
speed."
> 
> Would that statement refer to a local video card or in the server 
> itself ? as my local machine is already running accelerated.
> 
> Would one of the devs be able to cast some light on where I should 
> look to tune the performance?

NX works by running an X server ( a virtual workstation ) on the remote
X client ( the NX server ) and then sending compressed screen shots to
your X server ( your workstation ).

If you are trying to use GL apps remotely then it will run very slowly, 
unless
you use virtualGL with an accelerator card ( on your server ).

The "statement" above refers to to the video card on your workstation.

The "a more recent version of the X server" means the latest NX libraries 
on the
FreeNX server and the latest nomachine (or whatever you use) client.


Some probably obvious things.

You can speed things up (a bit) by maximizing the caches on the NX client,
using the fastest network connection you can, and setting the nomachine
client to the type of WAN that you are using.

This is about all the tuning you can do.

Making sure your server hardware is up to the job of compressing all this
display stuff is a very good idea.

Using up-to-date drivers for your workstation graphics card may help a 
bit.

Reducing the amount of NX traffic will also help, and for slow links is
probably the most significant thing you can do eg. minimizing windows
which are actively changing, reducing colours etc

Dragging windows about slowly or rotating images will cause lots of
activity because the more and more often your screen changes, the less
effective is the caching.


> 
> -- 
> Thanks, Phil
> ________________________________________________________________
>      Were you helped on this list with your FreeNX problem?
>     Then please write up the solution in the FreeNX Wiki/FAQ:
> 
> 
http://openfacts2.berlios.de/wikien/index.php/BerliosProject:FreeNX_-_FAQ
> 
>          Don't forget to check the NX Knowledge Base:
>                  http://www.nomachine.com/kb/ 
> 
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