Forum: GNU Radio [Fwd: [FFTW-announce] FFTW 3.2-alpha2 is available, Cell sup

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3596cfe1d579c65b9babd35e8787977c?d=identicon&s=25 Matt Ettus (Guest)
on 2007-03-19 17:54
(Received via mailing list)
This bodes well for cell support...
63d6de710dcc83e3c19af98ab6c401d7?d=identicon&s=25 Marcus Leech (Guest)
on 2007-03-19 18:42
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Matt Ettus wrote:
>
> This bodes well for cell support...
On a related subject, FFTW supports multi-threaded FFTs.  Is there
support for that in Gnu Radio yet,
  perhaps enabled automatically if it's running on a multi-CPU system?
815d7689c14621a2a5ed60b8bcde29b8?d=identicon&s=25 Chris Stankevitz (Guest)
on 2007-03-19 21:49
(Received via mailing list)
Marcus Leech wrote:
> On a related subject, FFTW supports multi-threaded FFTs.  Is there
> support for that in Gnu Radio yet,
>  perhaps enabled automatically if it's running on a multi-CPU system?

On another related note, I just found GPUFFTW (unrelated to FFTW) which
runs FFTs on your GPU (graphics card) which apparently has parallel
processing facilities.

CHris
3719f4fea703e38bcbf8de6fe6bcdf55?d=identicon&s=25 Martin Dvh (Guest)
on 2007-03-19 23:40
(Received via mailing list)
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.

Greetings,
Martin
E16be4811324adf8f26be26d77e9d29d?d=identicon&s=25 Robert McGwier (Guest)
on 2007-03-20 00:49
(Received via mailing list)
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.

Bob



Martin Dvh wrote:
>
>
--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"Taking fun as simply fun and earnestness in earnest shows
how thoroughly thou none of the two discernest." - Piet Hine
745d8202ef5a58c1058d0e5395a78f9c?d=identicon&s=25 Eric Blossom (Guest)
on 2007-03-20 15:21
(Received via mailing list)
On Mon, Mar 19, 2007 at 06:41:16PM +0100, Marcus Leech wrote:
> Matt Ettus wrote:
> >
> >This bodes well for cell support...
> On a related subject, FFTW supports multi-threaded FFTs.  Is there
> support for that in Gnu Radio yet,
>  perhaps enabled automatically if it's running on a multi-CPU system?

No support for it at this point.

Feel free to try it out :)

Eric
D6a91d99ad5598ef59dbe5e9f4d98d46?d=identicon&s=25 Joshua Lackey (Guest)
on 2007-03-21 00:15
(Received via mailing list)
Quoting Eric Blossom (eb@comsec.com):
> On Mon, Mar 19, 2007 at 06:41:16PM +0100, Marcus Leech wrote:
> > Matt Ettus wrote:
> > >
> > >This bodes well for cell support...
> > On a related subject, FFTW supports multi-threaded FFTs.  Is there
> > support for that in Gnu Radio yet,
> >  perhaps enabled automatically if it's running on a multi-CPU system?
>
> No support for it at this point.

I played around with FFTW's support of multi-threaded FFTs on a
dual-proc (not dual-core) machine a few years ago.  It was slower unless
you were doing a transform with 100,000 points or so.  (Or thereabouts.)

Unless things have changed drastically, it was rather dissapointing and,
obviously, not worth it.


>
> Feel free to try it out :)
>
> Eric
>
>
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> Discuss-gnuradio@gnu.org
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--
Joshua Lackey, PhD. -- jl@noether.uoregon.edu
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