Dual core AMDs (was Re: [Gllug] Recording Ogg streams?)

[Christian Smith]

On Tue, 12 Jul 2005, John Hearns wrote:

>On Tue, 2005-07-12 at 00:17 +0100, Chris Bell wrote:
>
>
>>    By contrast, the Intel Pentium II onwards use a RISC (reduced instruction
>> set computer) core running at extremely high speed to emulate the CISC 486
>> and Pentium I. It uses a long pipeline, which has to be cleared and refilled
>> frequently.
>>    Is the trend now towards ever more complex CISC architectures, or RISC
>> chips designed for efficiency? We hear about overheating problems, but are
>> we just running unneccessary hardware?
>>    I can understand the need for specialist chips for number crunching, but
>> what about server applications?
>I'll leave others to answer that question.


Even Intel wouldn't trend towards more complex CISC. They've been there,
done that and it was a disaster. Itanium has flopped so far, but i432 was
an order of magnitude less successful, being more expensive but about 4x
slower than Intel's then current 80286.
http://en.wikipedia.org/wiki/Intel_i432

IA64 was a move to be "beyond RISC", to make the hardware even simpler and
leave parallelism to the compiler, but Itanic has thus far failed to
deliver volume penetration due to cost and compiler complexity.


>The RISC/CISC wars are over, and I think the answer is that CISC has
>won, with elements of RISC, as you say.


I think RISC pipeline techniques won, but for general purpose desktops
computing, x86 (specifically, not CISC) won just based on the Wintel
duopoly. Outside of desktop computing, RISC wins the day (ARM and MIPS
dominate embedded 32bit computing.) with RISC still being the basis of
most UNIX servers. Wintel is pushing into the high end server market.

The only other prevelent CISC processors (68k, VAX) died long ago...


>
>Large caches are needed, because there is a lot of instruction prefetch
>and also speculative prefetch.
>
>
>Re. the need for specialist chips.. Noooooooo..... the Beowulf
>revolution came about by using common off the shelf components,
>ie ordinary PCs and general purpose CPUs and motherboards,
>instead of exotic custom chips. Even now, not my area of expertise,
>the 64 bit chips are designed for the mass market of webservers
>and database servers, graphics workstations etc.
>
>
>But re. specialised chips there IS a big interest in the HPC world in
>the Cell processor, coming to a Playstation near you soon.


Arstechnica had a piece on Cell and xbox360) processors.  Basically, don't
hold your breath, you still get what you pay for...
http://arstechnica.com/news.ars/post/20050629-5054.html


Christian

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