Can't generate workable fftw wisdom

[rknobbe]

I've tried multiple times with fftw-3.3.7 (configure --enable-threads --enable-float) but cannot get ka9q to read the wisdom files correctly.

I generate with

$ sudo fftwf-wisdom -v -T 1 -o /etc/fftw/wisdomf rof500000 cob36480 cob1920 cob1200 cob960 cob800 cob600 cob480 cob320 cob300 cob200 cob160

and copy that same wisdom file to /var/lib/ka9q-radio/wisdom.

But cannot overcome the fftwf_import calls to succeed. What am I doing wrong?

I'm running

Distributor ID: Ubuntu
Description:    Ubuntu 24.04.4 LTS
Release:        24.04
Codename:       noble

on an Intel(R) Core(TM) i3-6100T CPU @ 3.20GHz

:~/ka9q-radio/config$ sudo -u radio radiod -v -v   radiod@fm.conf 
KA9Q Multichannel SDR main.c                                  
Copyright 2026, Phil Karn, KA9Q. May be used under the terms of the GNU Public License                                     
   Repo: https://github.com/ka9q/ka9q-radio.git
 Commit: 6b967e7a6c0737648c2af7a01f203c211dc8693b
Loading config file radiod@fm.conf
Loading presets file /usr/local/share/ka9q-radio/presets.conf
Dynamically loading rx888 hardware driver from /usr/local/lib/ka9q-radio/rx888.so  
found rx888 vendor 04b4, device 00f1, manufacturer 'sdr prototypes', product 'RX888mk2', serial '000901080296172D', USB spee
d: Super (5 Gb/s), selected by default
RX888 Si5351 PLL: vco = 27,000,000 * (28 + 4/5) = 777,600,000 Hz; P1=3174, P2=2, P3=5
RX888 Si5351 output divider: samprate = vco / (2*(6 + 0/1)) = 64,800,000 Hz; P1=256, P2=0, P3=1
RX888 AGC off, nominal gain 20.0 dB, actual gain 19.9 dB, atten 0.0 dB, gain cal 1.4 dBm, dither off, randomizer off, USB qu
eue depth 16, USB request size 32 * pktsize 16,384 = 524,288 bytes (0.00404543 sec)
Block time 20.000 ms, block samples L=1,296,000, overlap 5 (20.0%) M-1=324,000 samples, forward FFT size N=1,620,000 real
FFTW version: fftw-3.3.10
fftwf_import_system_wisdom() failed
fftwf_import_wisdom_from_filename(/var/lib/ka9q-radio/wisdom) failed
fft: sched_setscheduler failed, Operation not permitted (1)
rx888 running

[rknobbe]

using fft-gen rather than fftwf-wisdom I was at least able to get the /var/lib/ka9q-radio/wisdom file to load. I'll continue down this path.

$ radiod -v -v radiod@fm.conf                                                           KA9Q Multichannel SDR main.c  
Copyright 2026, Phil Karn, KA9Q. May be used under the terms of the GNU Public License
   Repo: https://github.com/ka9q/ka9q-radio.git                                                                             
 Commit: 6b967e7a6c0737648c2af7a01f203c211dc8693b    
Loading config file radiod@fm.conf                                                                                          
Loading presets file /usr/local/share/ka9q-radio/presets.conf
Dynamically loading rx888 hardware driver from /usr/local/lib/ka9q-radio/rx888.so  
found rx888 vendor 04b4, device 00f1, manufacturer 'sdr prototypes', product 'RX888mk2', serial '000901080296172D', USB spee
d: Super (5 Gb/s), selected by default                                                                                      
RX888 Si5351 PLL: vco = 27,000,000 * (28 + 4/5) = 777,600,000 Hz; P1=3174, P2=2, P3=5
RX888 Si5351 output divider: samprate = vco / (2*(6 + 0/1)) = 64,800,000 Hz; P1=256, P2=0, P3=1
RX888 AGC off, nominal gain 20.0 dB, actual gain 19.9 dB, atten 0.0 dB, gain cal 1.4 dBm, dither off, randomizer off, USB qu
eue depth 16, USB request size 32 * pktsize 16,384 = 524,288 bytes (0.00404543 sec)
Block time 20.000 ms, block samples L=1,296,000, overlap 5 (20.0%) M-1=324,000 samples, forward FFT size N=1,620,000 real
FFTW version: fftw-3.3.10
Can't append to /var/lib/ka9q-radio/fft.log: Permission denied 
fftwf_import_system_wisdom() failed
fftwf_import_wisdom_from_filename(/var/lib/ka9q-radio/wisdom) succeeded
fft: sched_setscheduler failed, Operation not permitted (1)
rx888 running
Dropped CAP_NET_ADMIN capability

[ka9q]

I just this evening made some relevant changes. fft-gen now stores wisdom files with a version string appended to the file name, eg,
wisdom-fftw-3.3.10-sse2-avx-threaded.

On startup, both fft-gen and radiod now try to read three wisdom files:
/etc/fftw/wisdomf (the system wisdom which I no longer maintain);
/var/lib/ka9q-radio/wisdom (the previous ka9q-radio wisdom file); and
/var/lib/ka9q-radio/wisdom-fftw-3.3.10-sse2-avx-threaded (or whatever it should be), merging everything it finds.

FFTW simply ignores incompatible wisdom files and reports an error; this is probably what you're seeing. They can be incompatible because of CPU type, version, compile options, or threaded/non-threaded.

This should help avoid confusing (or accidentally destroying) incompatible wisdom files generated with different FFTW versions, or with different instruction sets enabled at compile time, in case you want to preserve them for possible future use.

Also, the wisdom files generated by FFTW in threaded mode (which ka9q-radio uses) are NOT compatible with those generated in non-threaded mode even if the thread count is 1. That's why I append 'threaded" to the file name, in case I want to do some performance comparisons with the non-threaded version.