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Re: [Discuss-gnuradio] [Fwd: [FFTW-announce] FFTW 3.2-alpha2 is availabl

From: Robert McGwier
Subject: Re: [Discuss-gnuradio] [Fwd: [FFTW-announce] FFTW 3.2-alpha2 is available, Cell support, MPI]
Date: Mon, 19 Mar 2007 19:48:18 -0400
User-agent: Thunderbird (Windows/20070221)

Essentially I disagree with everything Martin says here.

The 3.X support of FFT'w from FFTW is completely transparent to the end user for everything we are doing since the API on 3.1 and 3.2 are identical. You do a plan, you execute by passing the plan. About the only thing that "knows" you are running a K7 or a Cell is fftw?-wisdom. So if you need K7 support, don't upgrade from FFTW 3.1.2 and your program will not know the difference. You will because your CPU load will go down.

I am really glad we use floats in our processing. The double support on the Cell is HORRIBLE.


Martin Dvh wrote:
Matt Ettus wrote:
This bodes well for cell support...
Cell support is very very nice.

What I don't like is:
* Removed k7 support, which only worked in 32-bit mode and is
 becoming obsolete.  Use --enable-sse instead.

Older athlon processors (Thunderbird, duron) don't support SSE, they only 
support 3dnow.
And there are still a lot of these around. ( I only upgraded from one of these 
a few moths ago)

So for older non-SSE athlons, we need to support the current FFTW release.
For Cell support we need to support the next fftw release.

But I don't think it is nice to support multiple versions, especially if you 
want to use the new features of the later release.

I sent a mail to the FFTW guys about this, I hope they reconsider and just keep 
in the 3dnow code.


AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
"Taking fun as simply fun and earnestness in earnest shows
how thoroughly thou none of the two discernest." - Piet Hine

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