On Fri, Mar 25, 2016 at 7:53 AM, Michael Niedermayer <mich...@niedermayer.cc> wrote: > On Thu, Mar 24, 2016 at 05:50:52PM -0700, Ganesh Ajjanagadde wrote: >> 1. The most important change is the addition of a permute call to ensure >> that the comparison between fftw and avfft is fair, since fftw does not >> require the call. This is evident from the test code additions in the >> previous commit, and also from http://www.fftw.org/benchfft/. > > So FFTW is slower than AVFFT > but FFTW is faster than AVFFT + fft_permute ?
As can be seen from the benchmarks above, with fft_permute it is not a clear cut case, i.e for small lengths (< 512) they are roughly similar, but performance of avfft tanks for longer lengths relative to fftw. BTW, fftw has multithreading options, these benches don't exercise them. > > or do i misunderstand ? I did not give detailed info on this front, sorry. Turns out the conclusions change, at least on my Haswell, fixed clock to 1.9 GHz (same settings as for benches above). Without fft_permute, avfft is faster throughout: FFT 4 test Checking... max:0.000000 e:0 Speed test... time: 0.10 us/transform [total time=1.71 s its=16777216] FFTW 4 test Checking... max:0.000000 e:0 Speed test... time: 0.11 us/transform [total time=1.86 s its=16777216] FFT 8 test Checking... max:0.000000 e:5.21541e-08 Speed test... time: 0.11 us/transform [total time=1.88 s its=16777216] FFTW 8 test Checking... max:0.000000 e:6.70552e-08 Speed test... time: 0.13 us/transform [total time=1.10 s its=8388608] FFT 16 test Checking... max:0.000000 e:8.73796e-08 Speed test... time: 0.13 us/transform [total time=1.10 s its=8388608] FFTW 16 test Checking... max:0.000000 e:1.0382e-07 Speed test... time: 0.17 us/transform [total time=1.40 s its=8388608] FFT 32 test Checking... max:0.000000 e:1.63922e-07 Speed test... time: 0.07 us/transform [total time=1.10 s its=16777216] FFTW 32 test Checking... max:0.000000 e:1.92857e-07 Speed test... time: 0.17 us/transform [total time=1.40 s its=8388608] FFT 64 test Checking... max:0.000001 e:3.09466e-07 Speed test... time: 0.12 us/transform [total time=1.05 s its=8388608] FFTW 64 test Checking... max:0.000001 e:3.12211e-07 Speed test... time: 0.24 us/transform [total time=1.03 s its=4194304] FFT 128 test Checking... max:0.000002 e:4.97895e-07 Speed test... time: 0.26 us/transform [total time=1.11 s its=4194304] FFTW 128 test Checking... max:0.000002 e:6.00477e-07 Speed test... time: 0.51 us/transform [total time=1.08 s its=2097152] FFT 256 test Checking... max:0.000003 e:8.80516e-07 Speed test... time: 0.62 us/transform [total time=1.30 s its=2097152] FFTW 256 test Checking... max:0.000004 e:8.57262e-07 Speed test... time: 0.80 us/transform [total time=1.67 s its=2097152] FFT 512 test Checking... max:0.000008 e:1.25487e-06 Speed test... time: 1.28 us/transform [total time=1.35 s its=1048576] FFTW 512 test Checking... max:0.000004 e:1.31007e-06 Speed test... time: 1.36 us/transform [total time=1.43 s its=1048576] FFT 1024 test Checking... max:0.000008 e:1.90538e-06 Speed test... time: 2.75 us/transform [total time=1.44 s its=524288] FFTW 1024 test Checking... max:0.000010 e:1.94271e-06 Speed test... time: 2.81 us/transform [total time=1.47 s its=524288] FFT 2048 test Checking... max:0.000015 e:2.83741e-06 Speed test... time: 6.19 us/transform [total time=1.62 s its=262144] FFTW 2048 test Checking... max:0.000015 e:3.02253e-06 Speed test... time: 7.18 us/transform [total time=1.88 s its=262144] FFT 4096 test Checking... max:0.000023 e:4.2942e-06 Speed test... time: 15.24 us/transform [total time=2.00 s its=131072] FFTW 4096 test Checking... max:0.000023 e:4.43059e-06 Speed test... time: 16.20 us/transform [total time=1.06 s its=65536] FFT 8192 test Checking... max:0.000031 e:6.37783e-06 Speed test... time: 32.57 us/transform [total time=1.07 s its=32768] FFTW 8192 test Checking... max:0.000037 e:6.65281e-06 Speed test... time: 37.62 us/transform [total time=1.23 s its=32768] FFT 16384 test Checking... max:0.000046 e:9.52666e-06 Speed test... time: 70.86 us/transform [total time=1.16 s its=16384] FFTW 16384 test Checking... max:0.000046 e:1.00169e-05 Speed test... time: 87.51 us/transform [total time=1.43 s its=16384] FFT 32768 test Checking... max:0.000076 e:1.39189e-05 Speed test... time: 158.88 us/transform [total time=1.30 s its=8192] FFTW 32768 test Checking... max:0.000076 e:1.47434e-05 Speed test... time: 196.77 us/transform [total time=1.61 s its=8192] > > [...] > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > You can kill me, but you cannot change the truth. > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
