Xeon as a worthwhile platform?

Torbjorn Granlund tege@swox.com
11 Apr 2003 12:38:40 +0200

nisse@lysator.liu.se (Niels Möller) writes:

  But whatever the right cutoff point turns out to be, most of
  the cpu time will be spent doing the "small" base case
  multiplications, right?

Yes, roughly 90% of the time is spent in mpn_mul_1+mpn_addmul_1
(or in mpn_mul_basecase for the processors that have that in
assembly) in the Karatsuba range.

  So while the algorithm determines the exponent in the
  expression for the assymptotic running time, the speed of the
  base case is what determines the constants.

I couldn't have put it better myself!  :-)