Memory: locality

Memory hierarchy

Registers: small and fast

RAM: large and slow

Ideal: large and fast

Solution: range of memories from fast to slow

Fig 7.1

If memory accesses are random, can't do much, but programs typically have:

spatial locality: successive memory accesses tend to be close together in location

- sequential execution

- branches tend to be relatively small

- arrays

temporal locality: location, once accessed, will tend to be accessed again

within a small amount of time (loop: instructions and data)