I also notice a decline in PPS using Chemisist's code compare to the official (0.11). Getting an average of about 1800 PPS vs 2200 with official. I'm only running 12 threads as well, so it's not just affecting users with high thread counts.
Well, you're running with more threads than I was able to test (highest I got to was 8 on my core i7-950), so I'm not entirely sure why this is, though it could be that all threads are trying to access a single variable which is determining how long to let the sieve be woven for. I suppose that all these threads could end up blocking each other and cause a significant portion of idle time. It would be far more effective to have a sieve weaving time variable for each individual boost thread, but I'm not sure how to do this as I am entirely unfamiliar with the Boost library (I'm not a c++ programmer
)Actually with my FX 8350 I get just a bit less speed with your code than the official 0.11, and with my sempron 145 I get around 20% less with your code. Maybe it doesn't work well for AMD architectures?.
I wish I had a better answer than "I don't know." Unfortunately, I've done zero testing on the amd platform, sorry!