[Haskell-cafe] OpenGL performance issue on OSX

Thu May 22 18:46:56 UTC 2014

Em 21-05-2014 22:53, Michael Baker escreveu:
> I've added a VAO and reduced the inner loop to only a call to
> glDrawArrays which renders 8000 triangles (24000 vertices). The
> gameFrame function now benchmarks at ~86ms on my machine. I would expect
> it to be ~16ms because of vsync. I've pared down the entire project into
> this buildable cabal project of three files, most of which is OpenGL
> boilerplate: https://github.com/MichaelBaker/haskell-opengl. Running it
> benchmarks the problem area. For what it's worth, I also tried using
> glBufferSubData to update the vertex data, but that had no effect.

Your program is segfaulting for me on Linux:

$ cabal clean
$ cabal configure --disable-executable-stripping --ghc-option=-debug
  [...]
$ cabal build
  [...]

$ LC_ALL=C valgrind ./dist/build/opengl/opengl
==21335== Memcheck, a memory error detector
==21335== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==21335== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info
==21335== Command: ./dist/build/opengl/opengl
==21335==
warming up
estimating clock resolution...
mean is 38.15961 us (20001 iterations)
found 583 outliers among 19999 samples (2.9%)
  328 (1.6%) high mild
  254 (1.3%) high severe
estimating cost of a clock call...
mean is 1.177577 us (66 iterations)
found 3 outliers among 66 samples (4.5%)
  2 (3.0%) high mild
  1 (1.5%) high severe

benchmarking gameFrame
==21335== Invalid read of size 8
==21335==    at 0x4C2CB30: memcpy at GLIBC_2.2.5 (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==21335==    by 0x5C1E1A4: ??? (in /usr/lib/nvidia/libGL.so.337.19)
==21335==    by 0x5DC2: ???
==21335==    by 0xFF2FFFFFFFF: ???
==21335==    by 0xFEF: ???
==21335==    by 0xFEF: ???
==21335==    by 0xAC4285F: ???
==21335==    by 0x5EF4BB5: _XSend (in /usr/lib/libX11.so.6.3.0)
==21335==    by 0xAE456DF: ???
==21335==    by 0xAE460A7: ???
==21335==    by 0x5DC2F: ???
==21335==    by 0xAE455EF: ???
==21335==  Address 0xfe8 is not stack'd, malloc'd or (recently) free'd
==21335==
==21335==
==21335== Process terminating with default action of signal 11 (SIGSEGV)
==21335==  Access not within mapped region at address 0xFE8
==21335==    at 0x4C2CB30: memcpy at GLIBC_2.2.5 (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==21335==    by 0x5C1E1A4: ??? (in /usr/lib/nvidia/libGL.so.337.19)
==21335==    by 0x5DC2: ???
==21335==    by 0xFF2FFFFFFFF: ???
==21335==    by 0xFEF: ???
==21335==    by 0xFEF: ???
==21335==    by 0xAC4285F: ???
==21335==    by 0x5EF4BB5: _XSend (in /usr/lib/libX11.so.6.3.0)
==21335==    by 0xAE456DF: ???
==21335==    by 0xAE460A7: ???
==21335==    by 0x5DC2F: ???
==21335==    by 0xAE455EF: ???
==21335==  If you believe this happened as a result of a stack
==21335==  overflow in your program's main thread (unlikely but
==21335==  possible), you can try to increase the size of the
==21335==  main thread stack using the --main-stacksize= flag.
==21335==  The main thread stack size used in this run was 8388608.
==21335==
==21335== HEAP SUMMARY:
==21335==     in use at exit: 1,222,944 bytes in 665 blocks
==21335==   total heap usage: 5,445 allocs, 4,780 frees, 78,290,922
bytes allocated
==21335==
==21335== LEAK SUMMARY:
==21335==    definitely lost: 10,752 bytes in 12 blocks
==21335==    indirectly lost: 0 bytes in 0 blocks
==21335==      possibly lost: 519,934 bytes in 2 blocks
==21335==    still reachable: 692,258 bytes in 651 blocks
==21335==         suppressed: 0 bytes in 0 blocks
==21335== Rerun with --leak-check=full to see details of leaked memory
==21335==
==21335== For counts of detected and suppressed errors, rerun with: -v
==21335== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 3 from 2)
Falha de segmentação (imagem do núcleo gravada)

$ gdb ./dist/build/opengl/opengl
GNU gdb (GDB) 7.7.1
[...]
Reading symbols from ./dist/build/opengl/opengl...(no debugging symbols
found)...done.
(gdb) run
Starting program: /tmp/haskell-opengl/dist/build/opengl/opengl
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
warming up
estimating clock resolution...
mean is 1.346329 us (640001 iterations)
found 4071 outliers among 639999 samples (0.6%)
  3860 (0.6%) high severe
estimating cost of a clock call...
mean is 81.51352 ns (10 iterations)
found 1 outliers among 10 samples (10.0%)
  1 (10.0%) high mild

benchmarking gameFrame

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff5c5ece0 in _wordcopy_fwd_aligned () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007ffff5c5ece0 in _wordcopy_fwd_aligned () from /usr/lib/libc.so.6
#1  0x00007ffff5c595f5 in __memmove_sse2 () from /usr/lib/libc.so.6
#2  0x00007ffff6dff1a5 in ?? () from /usr/lib/libGL.so.1
#3  0x00007ffff6e01ada in ?? () from /usr/lib/libGL.so.1
#4  0x0000000000407b91 in ceGc_info ()
#5  0x0000000000000000 in ?? ()

Cheers,

-- 
Felipe.

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