After a several-month hiatus, I again have some decent CPU time on a colleague's pair of SGIs. On a 195MHz R10000 with 4MB L2 cache, Mlucas 2.7z is getting .27 seconds per iteration at FFT length 384K. Compared to George's posted timing of .211 sec on a 400MHz PII, that's a relative performance of 160%, which is the highest I've ever seen - it's even a little better than on an Alpha 21264 with same-size L2 cache, although the latter runs at a much higher clock rate. (On a 250MHz R10000 with a smaller 1MB L2 cache, Mlucas needs .29 sec, for an RPI of 116%.) I think SGI's problem is that although the R10K and R12K can do about the same amount of work per cycle as the Alpha 21264, SGI can't seem to jack up the MHz anywhere near the 21264, nor can they sell them as cheaply (one can get a 500MHz PC-style 21264 for around $3000 nowadays.) But for those of you who have access to them, the SGIs are nice Mersenne engines. -Ernst _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
