Re: [Discuss-gnuradio] Upgrade (downgrade?) to a Q6600 CPU

[Marcus D. Leech]

Bob McGwier wrote:
> The easiest and quickest way is to set environment variables
>
> export CFLAGS="-O3 -msse -msse3 -mfpmath=sse"
> export CXX CFLAGS="-O3 -msse -msse3 -mfpmath=sse"
> ./bootstrap
> ./configure (with your usual settings)
>
> This will ask the compiler to use SIMD instructions to your advantage
> wherever possible and  will turn on the more aggressive optimizations that
> is currently done by default in GnuRadio.  BUT, the big win comes from you
> restructuring your code to take advantage of the multiple cores.  This is
> not done automatically.  It must be done by design in the application.
>
> Bob
>   
Yup, I found all that in the "configure" file, and rebuilt.  It improved
performance marginally, from being able
  to handle 4.5Mhz without too many uOuO to about 5.33Mhz with the same
level of overruns.

Also, I looked into the process details of the process running
usrp_ra_receiver.py, and found that it had
  25 threads.  That must mean that each block runs in its own thread
now?   I'm intrigued by multi-threaded
  FFT (FFTW3 can do this if you ask it to), but I don't think Gnu Radio
takes advantage of that, and it's
  not clear how much of a win it would be--unless the FFT length is
quite long.

-- 
Marcus Leech
Principal Investigator, Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org