Different implementations of a simple Collatz iterator and their performance
The Collatz conjecture was proposed by Lothar Collatz in 1937. The conjecture is also known as the 3n + 1 conjecture.
The procedure is that if n is divisible by two then divide by two, else multiply by 3 and add 1, iterate until n reaches 1. The unproven conjecture is that for all values of n the procedure will always reach 1.
The benchmark times the iteration of the 226 first values of n.
Contents
Visual C++
Vista 64, 2.4 GHz core 2 Q6600
22.1s C++ 64 bit exe, one thread, unrolled 1000x 30.5s C++ 64 bit exe, one thread, unrolled 10x 45.9s C++ 32 bit exe, one thread, unrolled 1000x 49.2s C++ 64 bit exe, one thread, not unrolled 53.3s C++ 32 bit exe, one thread, unrolled 10x 76.1s C++ 32 bit exe, one thread, not unrolled
Vista 32, 2.66 GHz core 2 E66750
41.3 C++ 32 bit exe, one thread, unrolled 1000x 47.7 C++ 32 bit exe, one thread, unrolled 10x
Visual Basic 2008
Vista 64, 2.4 GHz core 2 Q6600
55.4s VB .net exe, one thread
Vista 32, 2.66 GHz core 2 E66750
66.4 VB .net exe, one thread
x86 assembly language
CUDA
1.625 GHz GTS 512,
2.3s CUDA 128 blocks x 256 threads
