[RC5] Performance on P-IV

Stephen Garrison garrison at ChE.UDel.Edu
Thu May 10 15:01:55 EDT 2001

IMHO there is a more important item than the pipeline depth. If I remember
correctly, the P-IV is entirely hardwired to do 64 bit instructions only.
Any P-III or earlier used 32 bit instructions. So, anything written for an
earlier Pentium, ie the dnet code, has to be translated by chip into 64
bit code. And, this translation process is generally extremely slow.

Until the dnet people get a chance to rewrite the assembly code in IA-64
(the new instruction set) instead of x86, the core is going to be
SSSLLLOOOWWW. Once the code is rewritten to use all of the new features of
the chip, including the longer pipeline, it should be much faster. 

As for how it will then compare per MHz with an Apple or an AMD machine, I
have no clue. But I bet it will be much improved at the very least.

My $0.025 (adjusted for inflation)

Stephen Garrison

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