PPC SIMD for devel_0_37 was: [PD-dev] cvs write access

[cgc at humboldtblvd.com]

I will have look in the next few days.  Alternately, you can mail me the 
scalar routines and your altivec versions, which would get a faster response.  

Typical Altivec gains on single precision FP like pd audio should be about 250-
350%.  If not then you are doing something wrong. ;)  Even a lowly 400 mhz G4 
can saturate just about any bus on any PC - the peak FLOPS on that chip is 
something like 3.2GB/sec using the fused multiply add - so you can definitely 
run your code up to 700MB/sec of throughput on one no problem.  

Of course most of pd's audio code could be written much better for PPC in the 
first place, so a full massage with all the loop-unrolling, load-hoisting and 
Altivec could be up to 8-10x faster than the scalar.  No promises, but it is 
possible.

Oh and the C code intrinsics are fine - there's no need to do assembly unless 
you really, really want to play 'beat the compiler'.  I've gotten to where I 
can bully GCC into decent output without resorting to asm.

cgc

Quoting Thomas Grill <t.grill at gmx.net>:

> Hi all,
> i implemented SIMD support for PPC processors to the devel_0_37
> branch.
> This will currently only be used if "-faltivec" is (manually) added to
> 
> the CFLAGS in the makefile. Needless to say, this won't work on G3 
> cpus.
> Since my experience with Altivec is limited, i would be grateful if one
> 
> of the SIMD experts could have a look. I'm using the mid-level 
> mnemonics, not direct assembly code. Some functions are still lacking.
> The amount of cpu saving (at least on my PB 400) is not as impressive 
> as with the Intel/SSE implementation. I would attribute this to the 
> slow memory of my machine.... probably newer machines perform better.
> 
> best greetings,
> Thomas
> 
> 
> Anfang der weitergeleiteten E-Mail:
> 
> > Von: Thomas Grill <t.grill at gmx.net>
> > Datum: 28. Dezember 2003 04:03:14 GMT+01:00
> > An: pd-dev at iem.at
> > Betreff: [PD-dev] cvs write access
> >
> > Hi all,
> > it seems that i can't commit to the pd cvs repository anymore. Could
> 
> > one of the admins please look into it?
> >
> > best greetings,
> > Thomas
> >
> >
> > _______________________________________________
> > PD-dev mailing list
> > PD-dev at iem.at
> > http://iem.at/cgi-bin/mailman/listinfo/pd-dev
> >
> 
> 
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