How fast GMP can be on Opterons?

Torbjorn Granlund
22 Apr 2003 23:39:55 +0200

Guillermo Ballester Valor <> writes:

  Because today is the AMD Opteron launch day I'm wondering how fast this new 
  chip can work with GMP.
  I see some impressive data at :
  1) Latency for a 64x64 bits mul: 4 cycles.
  2) A mul can be dispached every cycle
  3) A 64 bit add every cycle
  In an ideal world it could be more than 4 times faster clock by clock than 
  current Athlons, what is remarkable. 
I expect it to be more than 4 times faster, thanks to the 8 added
registers, r8...r15.  Perhaps we could reach 2 cycles/limb for
the critical operation mpn_addmul_1.  That would imply an 8-fold
speedup, clock-for-clock compared to Athlon.