Torbjorn Granlund wrote: > > Please do, and let me and Niels know if it takes more than 45s. Your > > test case takes 28s on my 3.3 GHz Sandy bridge system with our current > > code. I'm a little disappointed the code doesn't beat the old code more > > for small factorisations. > > So on my 2.1GHz i3-2310M, running over the range 452,930,477 to 472,882,027. > > old broken code = 14m > old fixed code = 18m > new code = 63s > > OK, this is about 60% slower than I would have expected. Our code at > http://gmplib.org:8000/factoring/ should run at about 39s on your > system. (I am using gcc 4.7.1.) > > I haven't looked at the final version that went into codeutils, so I > have no idea why it runs slower. A wild guess is that its actual input > or tokenisation has been slowed down. For smallish numbers, such things > can dominate over actually factoring the numbers. > > I think the current coreutils factor performance for smallish numbers > might be sufficient. (Larger numbers than 2^100 need a bit too much > time, but we are working on a fix.)
When I compare the factor built from http://gmplib.org:8000/factoring/, and the one in coreutils.git I see these single-trial times: (on a 3.2GHz i7-970) $ seq 452930477 472882027|env time ./factor > k 29.28user 0.44system 0:30.85elapsed 96%CPU (0avgtext+0avgdata 548maxresident)k 0inputs+1011088outputs (0major+162minor)pagefaults 0swaps ... $ seq 452930477 472882027|env time /cu/src/factor > k 26.47user 0.48system 0:28.07elapsed 96%CPU (0avgtext+0avgdata 692maxresident)k 0inputs+1011088outputs (0major+205minor)pagefaults 0swaps I.e., a 9% improvement. Compiled with bleeding edge gcc 4.8.0 20121007.
