[Freeciv-Dev] Re: Render speed test with imlib/xrender/sdl/pixbuf/ftwl

[Raimar Falke <i-freeciv-lists@xxxxxxxxxxxxx>]

On Sat, Mar 26, 2005 at 04:55:10PM +0000, Vasco Alexandre Da Silva Costa wrote:
> On Mon, 21 Mar 2005, Raimar Falke wrote:
> 
> > The task is to blit 4096 times a 100x100 png picture with alpha
> > channel to a 320x320 png picture. The position varies based on a
> > PRNG. Afterwards the result is shown to make sure that all produce the
> > same results. This task was previously identified as the main
> > bottleneck (about 80% of the CPU time) in the ftwl client.
> ...
> >
> > Results for my computer:
> > Time: 0.310 sec for Imlib2 off-screen.
> > Time: 0.584 sec for FTWL off-screen.
> > Time: 1.169 sec for pixbuf off-screen.
> > Time: 1.875 sec for Xrender on-screen.
> > Time: 1.899 sec for Xrender off-screen.
> > Time: 2.662 sec for SDL off-screen.
> >
> ...
> > If I disable the MMX support in imlib it produces
> > Time: 1.184 sec for Imlib2 off-screen.
> 
> You are falling into the same trap I fell. Micro-benchmarks are *evil*. Do
> not trust them. Never ever. That test is running inside the CPU L1 cache.
> With as many sprites as we use, plus offscreen stores, the real program
> will *not* fit in L1, or even L2, cache.

There is one value you can draw from these benchmarks. The give the
minimal time for these operations.

> Xrender to the best of my knowledge is not optimized for most drivers, it
> usually uses a slow software render. GdkPixbuf is also quite atrocious,
> despite having some MMX optimizations. SDL is often better, *if* compiled
> properly.

This is roughly also what I found out. In addition Per is right that
SDL performs badly if you don't convert all images to the same format
before.

> Nothing will beat pure X11 Pixmaps in performance.

They only have one problem: they don't support transparency.

        Raimar

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