[linux-audio-dev] GTK performance?

Jens M Andreasen jens.andreasen at chello.se
Thu Apr 28 09:45:57 UTC 2005

Hi all!

The other day I dressed up my application with a fancy g5-ish pixmap
theme. Looks good and expensive :) 

As it turned out, it really was expensive (counting cpu-clocks.)

Using Page Up/Down to manipulate a scale, I get 100% cpu at times when
the the scale is at max (respectively min), hence no redrawing should
take place (because oldValue == newValue.)

I then measured X using an Xterm, holding down a key to get the key to
repeat. Really, no sweat! Just a srolling window with gibberish. So X is
as far as I can see not at fault. 

Is it gtk then? Or the pixmap engine?

I thought I'd go and listen to the horses mouth and fired up The
Gimp ...

Uhmm! Those guys really do not wish to use the pixmap engine and
replaces the scales with what comes out of the eazel-engine (Crux &
With key Page Up/Down and the eazel-engine, I still get 20% CPU. 
This is kind of expensive for essentially doing nothing.

My conclusion is that there is something deeply wrong inside gtk,
regarding handling of signals and/or redraw. This is bad news for RT
audio people using gtk.

In comparison, letting FlightGear redraw the polygons of the Himalaya
ranges looks kind of cheap :-/


Reference machine: 1.1Ghz Celery. Gtk-2.0


  c[]  //  Jens M Andreasen

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