Am Freitag, 11. November 2011 14:33 CET, Michel Dänzer <mic...@daenzer.net> schrieb: > On Fre, 2011-11-11 at 14:15 +0100, Theiss, Ingo wrote: > > Am Freitag, 11. November 2011 12:09 CET, Michel Dänzer <mic...@daenzer.net> > > schrieb: > > > > > So It makes sense to find a glReadPixels in VirtualGL's glxSwapBuffers. > > > > > > Ah. I thought the time measurements in Ingo's original post were for the > > > Mesa glXSwapBuffers, not the VirtualGL one. If it's the latter, then > > > > > this makes sense. > > > > > > Ingo, I noticed that your 64-bit and 32-bit drivers were built from > > > slightly different Git snapshots. Is the problem still the same if you > > > build both from the same, current snapshot? > > > > > > If yes, have you compared the compiler flags that end up being used in > > > both cases? E.g., in 64-bit mode SSE is always available, so there might > > > be some auto-vectorization going on in that case. > > > > I´ve rebuild my 64-bit and 32-bit drivers from a fresh Git snapshot > > and turned on all processor optimizations in both builds. > > But nevertheless the readback performance measured inside VirtualGL is > > only half of the 64-bit readback performance and of course the > > rendered window sceene is noticeable slower to :-( > > > > Here are the compiler flags used. > > > > 32-bit: > > > > CFLAGS: -O2 -Wall -g -m32 -march=amdfam10 -mtune=amdfam10 > > -fno-omit-frame-pointer -Wall -Wmissing-prototypes -std=c99 -ffast-math > > -fno-strict-aliasing -fno-builtin-memcmp -m32 -O2 -Wall -g -m32 > > -march=amdfam10 -mtune=amdfam10 -fno-omit -frame-pointer -fPIC -m32 > > Have you tried adding -mfpmath=sse to the 32-bit CFLAGS? According to my > gcc documentation, that option is enabled by default in 64-bit mode but > disabled in 32-bit mode. > > Anyway, I guess there's room for optimization in glReadPixels...
Ok I have added -mfpmath=sse to the 32-bit CFLAGS and the readback performance increased from 30.44 Mpixels/sec to 48.92 Mpixel/sec. We are getting closer to the 64-bit performance. Next I try to find out what Brian has asked for ... Thanks so far! Regards, Ingo _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev