Re: [Mesa3d-users] Speed of Mesa on a SGI

[Andrew C A. <A.C...@dp...>]

Hugo Korwaser wrote:
> 
> Hi,
> I have an application built using VTK which uses opengl.
> When running using opengl libaries on a sgi (r5000, 128Mb, irix 6.5)
> the application behaves as expected. I was asked whether it was
> possible to run the application via an X-Term (eXceed 5.0) and so I
> have tried using Mesa (3.1) instead of the opengl libaries. I have
> two
> problems possibly related
>  1 - There is a huge speed drop. On a simple model, e.g. a cube,
> there
> is a delay in response of 10-15 seconds on a unloaded machine.
> This occurs whether the application is being run on the sgi's own
> screen or on a XTerm.
> I have tried setting MESA_BACK_BUFFER=p but it seems to make no
> difference
> 
>  2 - When run on the XTerm it seems to behave slightly more slugishly
> when the xterm is set to 256 colours.
> 
> Can anyone give any suggestions on how I can improve the situation.

1) Have you checked whether eXceed has a GLX option ?
If so, it is likely to speed things up a lot. You might even be able
to use the standard libraries.

2) Your SGI has significant hardware and software optimized for OpenGL;
The X-Term probably doesn't, so will be much slower.
Using the terminal you are limited by the speed of the network, which
is much slower than the conection between the CPU and the graphics
hardware.

3) I'm not surprised that the XTerm is slower at 256 colours - Mesa is
mapping several thousand/million colours into the 256 available.

4) I can't really explain the delay in response. In a sense the speed
drop is OK, but the delay is a real problem.