[SDL] SDL 1.3 on Mac OS X speed hit

[Frank Becker]

Sam Lantinga wrote:
>> Well, I'm glad it's improved.  I'm still looking at optimizations.
>> I have an old G4 iMac, and on that system my changes yesterday dropped
>> FPS from 78 to 36, so this may be a case where something that's good
>> for the new drivers is bad for the old drivers.  I'm going to try the
>> texture range extension today to see if I can get AGP transfers directly
>> from system memory.
> 
> So it turns out that on my G4 iMac if I use the client-storage extension,
> the texture data is asynchronously copied from system memory, which plays
> all sorts of havoc with a screen that is continually being updated.  It
> looks like the Core 2 MacBook Pro driver always blocks until the copy is
> complete, and ignores the other optimizing extensions at this point.
> 

FWIW, there's a sample that allows some comparison of the upload speeds:
http://developer.apple.com/samplecode/TexturePerformanceDemo/index.html

Both the GL_STORAGE_CACHED_APPLE hint and GL_UNPACK_CLIENT_STORAGE_APPLE 
are commented out.

With frame_rate set to 600 I get these results:

Both settings off: C2D gf7600  ~800MB/sec, G4 mac mini ~170MB/sec
Both settings on : C2D gf7600 ~1200MB/sec, G4 mac mini ~480MB/sec

I didn't see any screen garbage.

Cheers,
Frank.
--
Need a break? http://criticalmass.sf.net/