[mesa3d] performance on cygwin

[Brian Paul]

ZXPLESPAC001, Ext wrote:
> 	Just a little information message for Mesa3d performance on Cygwin.
> This is the ouput of progs/demos/readpix (from MesaDemos-6.0.1) :
> 
> - benchmark with "standard" cygwin x11 and my personnal build of glut-3.7
> (static)
> GL_VERSION = 1.2 (1.4 Mesa 5.0.2)
> GL_RENDERER = Mesa GLX Indirect
> Loaded 194 by 188 image
> Benchmarking...
> Result:  184 reads in 4.014000 seconds = 1671860.488291 pixels/sec

With indirect rendering, the images are getting sent over a socket 
from the server to the client.  It's not a fast path.


> - benchmark with Mesa 6.0.1 DLLs (build for cygwin with my personnal
> patches)
> GL_VERSION = 1.5 Mesa 6.0.1
> GL_RENDERER = Mesa X11
> Loaded 194 by 188 image
> Benchmarking...
> Result:  3186 reads in 4.000000 seconds = 29049948.000000 pixels/sec

In this case, the glReadPixels is basically a memcpy() from the color 
buffer to the user-allocated buffer.

If you'd run stand-alone Mesa, you'd get much faster results too.  I 
see 47103588 pixels/sec.

You should also test reading from the front color buffer too get the 
full picture.

-Brian