Lecture 7: Parallel Computing. Flynn's Taxonomy. Amdahl's Law.
- Wrap up Virtual Memory
- Intuitions for Parallel Computing
- Flynn's Taxonomy
- Amdahl's Law
Sequential computing is facing these steep hills to climb:
- Memory Wall: Speed difference between CPU & memory outside the chip
- ILP Wall
- Power Wall: Latency & limited communication bandwidth beyond chip boundaries
Take-home message: Try to stay away from long and winding conversations with the main memory
ILP elicits very complex microarchitecture
Instruction pipelining; Superscalar execution; Out-of-order execution; Register renaming; Speculative execution; Branch prediction
Predicting the future comes at the cost of microarchitecture complexity and power cost
Power, and not manufacturing, limits traditional general-purpose microarchitecture improvements
