1. Experience and Expertise of Designing SDN MPI_Bcast Khureltulga Dashdavaa, Susumu Date, Hiroaki Yamanaka, Eiji Kawai, Yasuhiro Watashiba, Kohei Ichikawa, Hirotake Abe, Shinji Shimojo 1

2. Background and Problem Software-Defined Network Research goal Proposed method: SDN_MPI_Bcast Evaluation Conclusion 2 Outline

3. N : Computing node P0, P1, P2, P3 : Running process MPI is playing great role in parallel programming. However, MPI implementation is not optimized for common network hardware, such as Gigabit Ethernet. 3 Network NNNNN P2 P3 P1 P0 Example: MPI_Bcast (basic collective communication) Background and Problem Main reason is that network has “static” resource, and cannot be controlled “dynamically”. ➡ Collective communication uses multiple unicast-based communication.

4. 4 Emergence of Software-Defined Network Controller part (how to deal with packets) Controller part (how to deal with packets) 3 1 11 2 2 4 Switch Switch 5 6 3 2 4 Switch 5 6 Traditional Network Software-Defined Network (SDN) : a new concept of network technology

5. 5 Software-Defined Network Emergence of Software-Defined Network Network Controller 3 1 11 2 2 4 SDN Switch Input Packet In : 2 Out : 1, 4, 6 5 6 3 2 4 SDN Switch 5 6 ➡ Network controller can control network “dynamically”. Software-Defined Network (SDN) : a new concept of network technology Example: Controls out going port or ports of incoming packet on switches.  In SDN, controller parts decoupled from devices (switches) and centralized to one place.

6. Integrate “dynamic” controller ability of SDN into MPI in order to overturn the assumption that network is “static” resource. 6 Reduce execution time of MPI_Bcast using SDN. Research goal 3 1 1 1 2 2 4 SDN Switch Network Controller 5 6 N NNNNNNNNN 3 2 4 SDN Switch 5 6 SDN MPI

7. 3 1 11 2 2 4 7 SDN Switch Network controller Data In ： 2 Out ： 1, 4 In ： 1 Out ： 2, 4 In ： 1 Out ： 2 5 6 N P0 An SDN feature that Network controller can choose outgoing ports of incoming packet on switches is adapted to MPI_Bcast as a duplication action. Proposed Method: SDN_MPI_Bcast N N NN P2 N N N NN P3 P1 3 2 4 SDN Switch 5 6 A process sends data only once for broadcasting data in our method 3 1 2 4 SDN Switch 5 6

8. 8 Change process numbers Data size ： 15.6 KiB (constant) Execution time of SDN_MPI_Bcast and MPI_Bcast. Experiment Result Change process number Execution time on initialization. Install Duplication Rules.

9. Introduced architecture of MPI_Bcast Leveraged Software-Defined Network. Our experiment result confirmed that SDN_MPI_Bcast is feasible. Future Works Stability and reliability of prototype implementation. Aim to SDN MPI. 9 Conclusion