[linux-audio-dev] GTK performance?

[Steve Harris]

On Thu, Apr 28, 2005 at 12:46:50 +0200, Jens M Andreasen wrote:
> On Thu, 2005-04-28 at 11:14 +0100, Steve Harris wrote:
> > On Thu, Apr 28, 2005 at 11:45:57 +0200, Jens M Andreasen wrote:
> > > 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.)
> > 
> > Unless you have an ultra-bleeding edge X setup a lot of the work of the
> > pixmap drawing is done by the CPU, thats quite a lot of maths. There is
> > some new tech which uses OpenGL to do the X drawing, which moves a lot of
> > the load off to the graphics card, but its not really available yet.
> > http://freedesktop.org/wiki/Software_2fXgl
> > 
> > This /really/ helps, for e.g. I have a beta version of meterbridge that
> > can use OpenGL or SDL (X) pixmaps, on my thinkpad (which has a comparitivly
> > hardcore graphics chip, but its only a laptop) I can fill the screen with
> > 32 scaled VU meters at about 3% CPU load, with SDL it maxes out the CPU
> > when I have about half that number of unscaled meters (the SDL code doesnt
> > do scaling, its too expensive).
> 
> Still leaves me wondering how on earth gtk can use the equivalence of a
> 200 Mhz pentium to figure out that nothing happened?

Well, determinging if two floating point numbers are the same is a non
trivial operation. There can be multiple encodings of, say, 1.3 depending
on how you got there.

I suspect they take a conservative view and always redraw if thye cant tell
thier the same.

- Steve