2007-06-18, 22:40 #21 geoff     Mar 2003 New Zealand 13×89 Posts gcwsieve 1.0.9 Some changes to the 32-bit SSE2 assembler (taken from sr5sieve 1.5.6) have had a big effect on P4 performance. Here are some times for my 2.9 GHz P4 at p=4200e9 using the 2947 term sieve file for the 2.5-5.0 million n range: Code: Version Single Thread 2 Hyperthreads ------- ------------- -------------- 1.0.7: 405 kp/s 700 kp/s 1.0.8: 446 kp/s (+10%) 720 kp/s (+3%) 1.0.9: 644 kp/s (+44%) 786 kp/s (+9%) I don't know whether other SSE2 machines will benefit by as much, or at all. My P4 is still better off LLR testing, but my P4/Celeron would now be more productive sieving, even just on the 2.5-5 million range. (It is the same speed as a full P4 for sieving, but only half speed for LLR testing which it is doing at the moment).