[openbeos] Re: app_server: MMX/SSE help wanted

On 2004-08-10 13:19:40 [+0200], Adi Oanca wrote:
> Christian Packmann wrote:

>> They've got a nice introductory article about SIMD architectures, going 
>> into some detail on MMX, SSE, 3DNow! and PowerPCs AltiVec; this would 
>> be a good read for anybody interested in the possibilities of SIMD: 
>> <http://arstechnica.com/cpu/1q00/simd/simd-1.html>
> 
>     Oh my god, Intel/AMD's SIMD implementation sucks BIG time!

Hey, x86 sucks big time, what did you expect? ;)

>     Altivec is by far the best implementation and the easiest to work 
>     with! Also, it using 32 completely independent registers would make
>     it about 2 times faster than SSE2/3.

For heavy scientific computations, not for desktop use. The main limitation 
with SIMD usually is RAM bandwidth, not processing power. 

Only the PPC970 is really interesting, as it has a frontside bus comparable 
to modern AMD/Intel CPUs. Motorolas 74xx series is crippled by its slow 
system bus, only 133MHz SDR IIRC - that's equivalent to a PIII. A 74xx will 
spend most of the time waiting for data to arrive - I can have that with my 
XP, which is much cheaper.

>     If only SSE4 == Altivec... ehhhh...

Well, x86/64 offers 16 128bit registers. That's enough for most purposes, 
even if it isn't quite as nice as AltiVec. But if we should ever get OBOS 
on  affordable PPC970 machines, I'd be tempted to recycle my x86 as 
Windows-only game console...

Bye,
Chris

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