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[Discuss-gnuradio] FFTW --enable-sse and gcc 3.4.4
From: |
Lee Patton |
Subject: |
[Discuss-gnuradio] FFTW --enable-sse and gcc 3.4.4 |
Date: |
Fri, 28 Oct 2005 17:40:08 -0400 |
I am happy to report that FFTW can be built with --enable-sse under
Fedora Core 3 using gcc 3.4.4.
Ignore the rest if this has never been a problem for you...
I originally built FFTW with gcc 3.4.2, and ran into the same problem as
these fine folks:
http://lists.gnu.org/archive/html/discuss-gnuradio/2005-04/msg00070.html
Basically, when running usrp_fft.py, a seg fault would occur in
libfftw3f.so. Building FFTW without --enable-sse using gcc 3.4.2 got rid
of the seg fault. This seemed to be a problem for Fedora Core 3 users
only.
An email from an FFTW developer revealed this was due to bug in gcc
3.4.[0123], and that it should be fixed in gcc 3.4.4. While all the
reports in this list came from FC3 users, he said he reproduced it under
Debian too.
I never bench marked w/ and w/o SSE enabled. So, I don't know if this is
actually improving performance. Although the FFTW site says it should.
I also noticed that the FFTW configure script thinks I have a Pentium
Pro, when I have the more specific Pentium M. A Pentium M is based on
Pentium Pro, but supposedly has better SSE support. I don't know how
true that is or not. Anyway, I changed the -mcpu=pentiumpro to -
mcpu=pentium-m, and did not notice any appreciable performance increases
in usrp_fftw.py. The FFTW developer said that the next release of FFTW
will have improved cpu detection support.
Are there standard benchmarking scripts distributed with gnuradio that I
could use to test if changing -mcpu or enabling/disabling SSE makes a
difference?
- Lee
- [Discuss-gnuradio] FFTW --enable-sse and gcc 3.4.4,
Lee Patton <=