[FreeNX-kNX] NX server performance

DRC dcommander at users.sourceforge.net
Fri Mar 14 23:42:13 UTC 2008

> Why do you use XShmPutImage? Perhaps with a normal PutImage 
> you would be more successful?

I use XShmPutImage() because it performs better in other X servers, such as
TurboVNC.  It doesn't provide much advantage in NX, but there's no
disadvantage to it either.  It performs about the same as other image
drawing methods, such as using XPutImage() or Pixmaps.  And all methods
suffer from the same high CPU overhead due to fbBlt().

I actually was able to eliminate the md5_process() overhead by setting the
GLX trap like we'd discussed earlier (I thought that it was already set--
mistake on my part.)  But the fbBlt() overhead is still a problem.

> No real idea ... Might be that the damage extension here 
> igves more harm than use? Tried to disable it: -ext -damage 
> on cmdline.

Good suggestion, but unfortunately it doesn't do anything.  damageCopyArea()
is still called for every XShmPutImage() call, and the performance overhead
is still there.  I'll ping the NX developers and see if they have any ideas.

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