1. INEL6067 Parallel Architectures Why build parallel machines? °To help build even bigger parallel machines °To help solve important problems °Speed – more trials, less time °Cost °Larger problems °Accuracy Must understand typical problems

2. INEL6067 Introduction °A parallel computer is “a collection of processing elements that communicate and cooperate to solve large problems fast” Speedup(p processors)=performance (p processors)/performance (1 processor) Speedup(p processors)=time(p processors)/time(1 processor)

3. INEL6067 °Can run a single parallel application Speed up the application °Can run multiple independent applications in multiprogramming environment High throughput °Combination of the two

4. INEL6067 Applications ---> Requirements Processing Communication Memory I/O Synchronization °Architect must provide all of the above Numeric Symbolic Combinatorial

5. INEL6067 Requirements ---> Examples Relaxation - near-neighbor communication Multigrid - 1, 2, 4, 8,... communication Numeric comp - Floating point Symbolic - Tags, branches Database - I/O Data parallel - Barrier synchronicity Dictionary - Memory, I/O

6. INEL6067 Communication requirements ---> Example °Relaxation °So, let’s build a special machine! ° But... pitfalls!

7. INEL6067 Specialized machines: Pitfalls Faster algorithms appear … with different communication requirements Cost effectiveness -Economies of scale Simpler hardware & software mechanisms -More flexible -May even be faster! –e.g. Specialized support for synchronization across multiple processors