stateless thin cliens with decent graphics performance - possible?

Csillag Kristof csillag.kristof at
Sat Jun 26 15:21:32 PDT 2010

2010-06-26 13:51 keltezéssel, Piotr Gluszenia Slawinski írta:
>> This is all good and well, but thanks to VNC, the graphics performance
>> is horrible, especially on the bigger screens.
>> (For example, on my 1600x1200 monitor, I can clearly follow the
>> full-screen windows refreshing, which is no big feat, since it takes
>> several seconds.)
> i use vnc myself, and usually network is the bottleneck.
The server and the client both have gigabit ethernet connections,
and sit on the same LAN, so I have not really considered this.

Besides, simple good ol' X has no problem running over the same network

> did you checked what is bottleneck in your case?
> if you are using decent thin clients, you could consider using
> i.e. tigervnc or other vnc server providing more robust, but
> lossy compression (using it myself, and it works pretty nice).
Thank you for the tip; I will look into TigerVNC.

> playing with i.e. deferupdate option on server and compresslevel
> on client is also worth trying.
> main difference from x session seems to be fact that while x session can
> i.e. clear screen with single command sent over network, it means
> sending whole screen data with vnc.
Yes, and this is exactly why I hope to use an X-ish solution, instead of
a VNC-ish one, of possible.
(Ideally, some kind of X proxy could solve my problem...)
> similiar issue occurs with remote X session. even though your app
> might be full-screen, it could modify on-screen contents using much
> smaller commands sent via tcp/ip, which may bring larger effect (i.e.
> text scrolling up/down), while vnc has to send whole data instead.
To put it simply, my experience until so far is that plain X rocks, and
RealVNC sucks (as far as speed is concerned, on a dual 1600x1200 setup.)
> quite good 'benchmark' of vnc vs plain X seems to be 'xaos', as it
> just sends whole 'result' of it's calculations to client as plain
> image buffer.
>  set it to'continous rotation' (press 'o' and select it).
> once started, check cpu usages, and network usages, irq
> load, etc. try to compare performance via vnc with various levels
> of compression and deferupdate setting, with 'bare' X session .
> try various sizes, and see how quickly performance drops once network
> saturates :)
Right now, I don't really have time for this, but later I will run some
tests with this.

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