When I was originally messing around with multi threading for my application, the use of measure gave a large improvement. Though I am using small fft sizes (1024) but high data rates. Also it was a custom c program. ________________________________________ From: discuss-gnuradio-bounces+bruce.stansby=postgrad.curtin.edu...@gnu.org [discuss-gnuradio-bounces+bruce.stansby=postgrad.curtin.edu...@gnu.org] on behalf of Marcus D. Leech [mle...@ripnet.com] Sent: Monday, 6 December 2010 3:05 PM To: Discuss-gnuradio@gnu.org Subject: [Discuss-gnuradio] Multi-threaded FFTW
I did some tests tonight using the multi-thread support in FFTW3. The changes to gri_fft.cc were relatively minor, but plugging this into the existing build environment will require a little surgery, since you need to add -lfftw3f_threads to the ld flags, and the ld flags for FFTW3F are intuited from pkgconfig by default, which doesn't include support for multi-threaded FFTW3F. I didn't do that surgery, instead manually setting the FFTW3F_LIBS environment variable before calling ./configure, and then doing the build. On my lowly Centrino-Duo laptop, I was able to measure a 40% throughput improvement between single-threaded and setting the thread count to 2, for a single forward FFT of size 2**19. The implementation allows you to set variables in the [fftw] section of the prefs file as follows: [fftw] nthreads=1 threshold=15000 measure=False nthreads: maximum number of threads that the FFTW3F scheduler will use threshold: the minimum FFT size before we turn on multi-threaded FFTW scheduling measure: whether the FFT setup uses FFTW_MEASURE or FFTW_ESTIMATE More tests in my lab tomorrow, on my 6-core Phenom II system. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
