1. 1J. Kim Web Science & Technology Forum Enabling Hardware Technology for Web Science John Kim Department of Computer Science KAIST

2. 2J. Kim Computing System Web Science & Technology Forum

3. 3J. Kim Moore’s Law Web Science & Technology Forum

4. 4J. Kim Increasing number of cores Rethinking the Design of Interconnection Networks

5. 5J. Kim Challenges for Future Hardware Energy-Efficient Mobile Systems –Need to extend battery life –Provide the performance capability of a laptop with a smaller power budget –Exploit parallelisms available in future multi/many-core processors Scalable Datacenter –Future datacenters will continue to increase in the number of servers interconnected –Need to minimize energy consumption Web Science & Technology Forum

6. 6J. Kim Energy Consumption Datacenters have a huge electricity bill –e.g.) US datacenters will consume 100 billion kWh at a cost of $7.4 billion per year [EPA report] Total cost of ownership is no longer dominated by the hardware but by Energy-Efficient Datacenters Source: C. Belady “In the data center, power and cooling costs more than the it equipment it supports”

7. 7J. Kim Which costs more? Web Science & Technology Forum 20mm

8. 8J. Kim Supercomputers to Datacenters Web Science & Technology Forum

9. 9J. Kim Can we leverage the network used in high-performance computing for datacenter networks? funded in part by Microsoft Research Asia Web Science & Technology Forum

10. 10J. Kim Existing approaches Tree –Oversubscribed –Bottlenecked root Fat tree –1:1 subscription –Costly as large number of switches With the number of servers growing Container0 Container1... TOR switches TOR switches With the number of servers growing Scale up Scale out High end router 10 slide from C. Guo

11. 11J. Kim Rethinking the Design of Interconnection Networks Flattened Butterfly John Kim, William Dally, Dennis Abts, “Flattened Butterfly: Cost- Efficient High-Radix Networks” ISCA 2007

12. 12J. Kim Dragonfly Topology [ISCA’08] Increase scalability by using a collection of routers as a ”supernode” Leverage the packaging hierarchy found in systems to match the hierarchical network of the topology? What is the challenge of mapping this topology? Adaptive Routing Web Science & Technology Forum

13. 13J. Kim Packaging Hierarchy Web Science & Technology Forum Rackable Systems Container

14. 14J. Kim Load-Balanced Routing Load-balancing required in both inter- and intra-container routing Randomized routing can be leveraged to load balance the channels Adaptive routing need to determine whether to route using minimal routing and nonminimal routing Approach : - Leverage the centralized management capability in datacenters and provide a centralized adaptive routing. - Focus on load-balancing the “elephant” flows while other short- lived flows can be routed minimally Web Science & Technology Forum