[Mesa-dev] Performance glxSwapBuffers 32 bit vs. 64 bit

[Michel Dänzer]

On Don, 2011-11-10 at 11:01 +0100, Theiss, Ingo wrote: 
> 
> The function calls of mesa/state_tracker/st_cb_readpixels.c:382 ->
> st_readpixels and mesa/main/pack.c:552 -> _mesa_pack_rgba_span_float
> clearly stands out when comparing the 32 bit and 64 bit profile.

I'm afraid that's a red herring, as I don't think glXSwapBuffers calls
glReadPixels under any circumstances. I suspect the time inside
glXSwapBuffers isn't spent on CPU cycles but rather waiting for some
kind of event(s). Offhand I don't know any better way to debug that than
attaching gdb, interrupting execution every now and then and hoping to
catch it somewhere inside glXSwapBuffers. Maybe others have better
ideas.


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer