Re: [Discuss-gnuradio] Weired GNURADIO Performance

[Mattias Kjellsson]

Firas Abbas wrote:
> Hi,
>
>   
> > On Sat, 5/2/09, Andrew Lutomirski <address@hidden> wrote:
> > I can speculate: some versions of Ubuntu (i.e. all the ones
> > I've actually looked at) seem to build fftw *without* SSE/SSE2.  
> >
> > --Andy
> >     
>
>
> Do FFTW have a function we can use to read if it is using SSE/SSE2?. If exist, 
> we can add a small program to gnuradio to warn about the missing of it.
>   
I think there is a function for that, but since I couldn't remember it, 
I went to fftw.org and I found this:


"SSE, AltiVec, and MIPS PS only work with |--enable-float| (above), 
while SSE2 only works in double precision (the default). The resulting 
code will /still work/ on earlier CPUs lacking the SIMD extensions (SIMD 
is automatically disabled, although the FFTW library is still larger)."

The default fftw is using double precision, but I have a feeling that 
the build- wiki for gnuradio sugested single- precision...

//Mattias