[Beowulf] Re: vectors vs. loops

Alan Louis Scheinine scheinin at crs4.it
Tue May 3 08:34:39 PDT 2005

There are very few types of computers with an adeguate
bandwidth to main memory to keep the vector units busy,
NEC is one of the few.

This thread of discussion has evolved, so that now there are
estimates of how much scientific code can be vectorized.
When indirect addressing does not impede vectorization, it is
my impression that alot of code can be vectorized but the
typical real-world problems have vectors much larger than
L1 cache and often much larger than L2 cache.

If the question boils down to the choice of hardware,
the amount of code that is vectorizable may not be the
key question, but rather: for any proposed vector hardware
what is the proposed solution for the memory bandwidth problem
when using that hardware?

best regards,
Alan Scheinine


  Centro di Ricerca, Sviluppo e Studi Superiori in Sardegna
  Center for Advanced Studies, Research, and Development in Sardinia

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