[RC5] Performance on P-IV

Bjoern Martin boris59 at gmx.net
Thu May 10 16:51:45 EDT 2001


>Hey I've got some sad sad sad statistics.
>[...]
>Hope somebody can explain this....

Doesn't make much sense to run statistics now, as the P-IV has
to be specially supported for - kind of at least. I only got 1
cent for this one as I'm no hardware guru:
The pipeline of the P-IV is pretty long (i think 12 clocks). This
means, every instruction takes 12 clocks. That's not a problem,
as when the first instruction moved on 1 clock, the second one
can start. So you might have a max of 12 instructions running the
same time. BUT: if the software isn't aware of this (i.e.,
compiled for older processors, as nearly 100% of today's software),
this isn't an advantage, but quite the opposite. Nowadays it's
pretty normat that an Athlon running 1,2 GHz outruns a P-IV 1,4
easily. This will improve in favor of the P-IV if you recompile
with optimized compilers (Intel's words), but Dnet's cores are
normally optimized in assembler. So just be a little patient.

So what do the gurus say, is this guess true? :)

Bye,

Bjoern, Team #6941

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