Override FFT3W... **** FAILED ****

[colin4124]

I run it in RPi 3, how to solve this:

gpu_fftw - Version 0.1.3-2-g3380

GPU FFT forward/reverse error = 0.147825ppm (nrms error)
GPU_FFTW/FFTW difference = 0ppm (nrms error)
GPU FFTW 1.56045 times faster (21267.1 ffts/sec, 47.021 usec/fft, fftw3: 13628.8 ffts/sec)

Override FFT3W... **** FAILED ****
Test suite ***** FAILED

[sergey-suloev]

gpu_fftw - Version 0.1.3-2-g3380

GPU FFT forward/reverse error = 0.140472ppm (nrms error)
GPU_FFTW/FFTW difference = 0ppm (nrms error)
GPU FFTW 0.972877 times faster (31611.6 ffts/sec, 31.634 usec/fft, fftw3: 32492.9 ffts/sec)

Override FFT3W... **** FAILED ****
Test suite ***** FAILED

[gtoal]

Same problem. I tried substituting armv7 for armv6 (and armv7l for armv6l) in the makefile but that didn't help (wouldn't compile - 'target CPU does not support ARM mode')

It looks to me that when running on an armv7, when compiled for armv6, the code is falling back to fftw3 mode which is why the runtimes are about the same for both calls.

gcc -march=armv7 -mfloat-abi=hard -mfpu=vfp -O3 -ffast-math -pipe -mtune=arm1176jzf-s -fstack-protector --param=ssp-buffer-size=4 -std=c99
-Wall -g -fvisibility=hidden -shared -fpic -Wl,-soname,libgpufftw.so -o libgpufftw.so.1 gpu_fftw.c gpu_fftw_util.c hello_fft/mailbox.c he
llo_fft/gpu_fft.c hello_fft/gpu_fft_base.c hello_fft/gpu_fft_twiddles.c hello_fft/gpu_fft_shaders.c -ldl -lfftw3
gcc -march=armv7 -mfloat-abi=hard -mfpu=vfp -O3 -ffast-math -pipe -mtune=arm1176jzf-s -fstack-protector --param=ssp-buffer-size=4 -std=c99
-Wall -g -fvisibility=hidden -shared -fpic -Wl,-soname,libgpufftwf.so -o libgpufftwf.so.1 gpu_fftwf.c gpu_fftw_util.c hello_fft/mailbox.c
hello_fft/gpu_fft.c hello_fft/gpu_fft_base.c hello_fft/gpu_fft_twiddles.c hello_fft/gpu_fft_shaders.c -ldl -lfftw3f
VSN="git describe --always --tags --abbrev=1 | sed 's/^v//'";
echo "#define GPU_FFTW_VSN "$VSN"" > vsn.h
gpu_fftwf.c:1:0: error: target CPU does not support ARM mode

[CharlieAt]

there appears to be two problems.

• hello_fft has evolved along with the device drivers below, so an update of hello_fft is needed, which requires minor changes to gpu_fftw.c.template to account for the changed complex structure.
• then the current debian requires the absolute path for LD_PRELOAD to work. this can be added to exec_other
  with those changes it runs on a pi zero.

[sergey-suloev]

I am not interested in this anymore. I am using classical fftw. Can we close this ?

[Dobbley2]

Hi CharlieAt, I'm trying to get this working on a pi zero. What are the changes you made?

[CharlieAt]

Hi Dobbley2,

copy the current hello_fft (/opt/vc/src/hello_pi/hello_fft/) over the hello_fft in the project.
then as per the 2 patches adapt the template file to account for the changed complex structure and make the LD_PRELOAD paths absolute (included patch assumes the .so files are in the current working directory)
0001-add-abs-path-for-preload.patch.txt
0001-fix-for-updated-hello_fft.patch.txt

[Dan-escu]

Is there a solution to this for the pi 3B? Attempting to run fftw in real-time with minimal delay and this may be the key! Thanks