On 6 July 2012 16:52, Mans Rullgard <mans.rullg...@linaro.org> wrote: > I ran my usual set of benchmarks of libav compiled with the current gcc > releases (hand-written assembly disabled). The results are in this > spreadsheet: > https://docs.google.com/spreadsheet/ccc?key=0AguHvNGaLXy9dHExeWZ1YWZ1c0s2VnpJRkl2bVRPU2c > > First the good news, almost everything is faster with 4.6+ than with > linaro-4.5. > > The bad news is that some things have regressed since 4.6, even if not > all the way back to 4.5 levels. A few especially problematic pieces > stand out: > > - The mp3 test performs 5-15% worse. This regression is (mostly) > attributable to the ff_mpadsp_apply_window_fixed [1] function. > We have looked at this one before. > > - FLAC is 9% slower in upstream 4.7/4.8 compared to Linaro releases. > Here flac_lpc_16_c [2] and flac_decorrelate_indep_c_16 [3] are > mainly to blame. >
Looking at this in the middle of the summit - In the flac_lpc_16_c code in the vectorized case could you take a look with perf and say which part is hot ? is it the top level nested loop over i and j or is it the loop that does a summation when i < len ? The non-vectorized case looks interesting because it might be a fallout with sched-pressure. > - MPEG2/MPEG4 decoding is ~10% slower with vectorisation turned on. > The culprit here is ff_simple_idct_8_c [4] function. > > - H.264 and DTS seem 1-2% slower, although this could be just noise. > > - Code size has increased by ~10% in all post-4.6 releases. > > In all cases, compiled with -O3 -mcpu=cortex-a9. The vectorised builds > all use -fvect-cost-model. Without this flag the results are much > worse. > > [1] > http://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpegaudiodsp_template.c;h=8a521d9d0ca0798c75f9cdfdf9887aa0c33c746a;hb=HEAD#l121 > [2] > http://git.libav.org/?p=libav.git;a=blob;f=libavcodec/flacdsp.c;h=a2e335b4de81188a61e1d62e970aa23204812973;hb=HEAD#l43 > [3] > http://git.libav.org/?p=libav.git;a=blob;f=libavcodec/flacdsp_template.c;h=0affe22ddb76325682aef46731722b068dd3a791;hb=HEAD#l51 > [4] > http://git.libav.org/?p=libav.git;a=blob;f=libavcodec/simple_idct_template.c;h=3c855e3825dc7b87747b8217b9955eae83528246;hb=HEAD#l315 > > > -- > Mans Rullgard / mru > > _______________________________________________ > linaro-toolchain mailing list > linaro-toolchain@lists.linaro.org > http://lists.linaro.org/mailman/listinfo/linaro-toolchain _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
