“Three Performance-Limiting Walls” is a term coined to represent the three important limiters of microprocessor performance – power use, memory use, and processor frequency. The three walls consist of – the power wall, the memory wall and the frequency wall. Personally, I think that of these three, the memory wall is the tricky one since it is non-intuitive for us to think of layered memory access rather than the more intuitive flat memory access. This graph nicely summarises the problem. Popular solutions include multi-core architectures, innovative memory architectures (Cell), and fundamental improvments in memory (eDRAM) for example.
Three Performance-Limiting Walls (slides 2-3)