Improved Barrier Algorithms for a Bus
- Separate arrival and exit trees, and use sense reversal
- Valuable in distributed network: communicate along different paths
- On bus, all traffic goes on same bus, and no less total traffic
- Higher latency (log p steps of work, and O(p) serialized bus xactions)
- Advantage on bus is use of ordinary reads/writes instead of locks
Software combining tree
- Only k processors access the same location, where k is degree of tree