Reducing Network Delay
Network delay component = f*h*th
- h = number of hops traversed in network
- th = link+switch latency per hop
Reducing f: communicate less, or make messages larger
Reducing h:
- Map communication patterns to network topology
- e.g. nearest-neighbor on mesh and ring; all-to-all
- How important is this?
- used to be major focus of parallel algorithms
- depends on no. of processors, how th, compares with other components
- less important on modern machines
- overheads, processor count, multiprogramming