64-bit double math performance
I have a science application that uses double math almost exclusively for some pretty heavy duty and long-running analyses.
I thought that by using a 64-bit OS and Java VM I would naturally see about a 2x performance boost, but this is NOT the case. Performance actually degrades a bit, as the Sun 64-bit FAQ explains is due to increased pointer size.
Why is there no performance increase for double math on the 64-bit VM? Doubles are 64 bit in size and the underlying 64 bit machine has a 64 bit data path. I would imagine that there is now one memory fetch per value rather than two.
What is going on here?