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ponto
18th February 2006, 12:13
I've compiled Qt 4.1 on several Linux machines and tried the demos with qtdemo. On each machine the demos were slow as hell, with about a framerate of 4 fps.

Does anyone know what the prerequisites are to get the demos at a reasonable speed?

yop
18th February 2006, 13:47
Are we talking about openGL? What's the output of:
glxinfo | grep direct

ponto
18th February 2006, 14:32
Are we talking about openGL? What's the output of:
glxinfo | grep direct

Here is the output



ponto@burns:~> glxinfo | grep direct
direct rendering: Yes


I do not think that opengl is a problem here, because games like Unreal Tournament 2003 are quite fast here. I also do not know whether the qtdemo app uses opengl.

wysota
20th February 2006, 20:41
Did you compile the demo in debug or release mode? (Simply speaking, is the binary of it "huge" (2MB) or "small" (200kB)?) It might be compiled in debug mode, which causes a major slowdown.

ponto
20th February 2006, 21:28
Did you compile the demo in debug or release mode? (Simply speaking, is the binary of it "huge" (2MB) or "small" (200kB)?) It might be compiled in debug mode, which causes a major slowdown.

I see that the qtdemo executable itself is linked against debug versions of the Qt libraries. Howver the demos themselves are linked against the release libraries. I also checked the compilation process and see that optimized binaries are build.

wysota
20th February 2006, 21:54
But is it just the qtdemo that is slow or all examples are slow?

ponto
20th February 2006, 22:50
But is it just the qtdemo that is slow or all examples are slow?

Most examples are as slow as qtdemo. For example the composite demo is really slow. Also slow are deform and pathstroke.
Mainwindow is not really slow but too slow for the shown effect.

wysota
21st February 2006, 00:28
Composite can be a bit slow, although I don't have direct rendering working, so that may be because of the driver.

nuntius
31st May 2006, 11:25
Disclaimer: X11 only

The source for qtdemo is in QTDIR/examples/tools/qtdemo.
Search for "slow" in displaywidget.cpp.
This message popped up *once* for me, I responded properly, and qtdemo ran fast. Every other time, its been slow as molasses.