Design code to fit in CPU Cache?

Question

When writing simulations my buddy says he likes to try to write the program small enough to fit into cache. Does this have any real meaning? I understand that cache is faster

Answer 1

If I were you, I would make sure I know which parts of code are hotspots, which I define as

• a tight loop not containing any function calls, because if it calls any function, then the PC will be spending most of its time in that function,
• that accounts for a significant fraction of execution time (like >= 10%) which you can determine from a profiler. (I just sample the stack manually.)

If you have such a hotspot, then it should fit in the cache. I'm not sure how you tell it to do that, but I suspect it's automatic.