Presentation on theme: "An Analytical Model for Worst-case Reorder Buffer Size of Multi-path Minimal Routing NoCs Gaoming Du 1, Miao Li 1, Zhonghai Lu 2, Minglun Gao 1, Chunhua."— Presentation transcript:
An Analytical Model for Worst-case Reorder Buffer Size of Multi-path Minimal Routing NoCs Gaoming Du 1, Miao Li 1, Zhonghai Lu 2, Minglun Gao 1, Chunhua Wang 1 1 Hefei University of Technology, Anhui Province, China 2 KTH Royal Institute of Technology, Sweden
Multi-path Routing NoC Prospects –Minimize network congestion and packet delay –Improve the load balance –Reduce power consumption –Fault tolerant routing Problem –Out of order P1 P2 P3 P4
disadvantage The area overhead. Low hardware utilization. With worst-case analysis, it can reduce the reorder buffer size with proper flow splitting configuration effectively. Out of Order  S. Murali, D. Atienza, L. Benini, and G. De Micheli, “A method for routing packets across multiple paths in NoCs with In-Order delivery and Fault- Tolerance gaurantees,” VLSI Design, vol. 2007, pp. 1–11, Solution 1: flow control –Prospects Easy to control Less hardware overhead –Side effect More congestion Longer packet delay Out of order packets Packet in need
Out of Order Solution 2: reorder buffer –Prospects Less on chip congestion Less re-arbitration time –Side effect Area overhead  M. Daneshtalab, M. Ebrahimi, P. Liljeberg, J. Plosila, and H. Tenhunen, “Memory- efficient on-chip network with adaptive interfaces,” Computer-Aided Design of ntegrated Circuits and Systems, IEEE Transactions on, vol. 31, no. 1, pp. 146–159, Out of order packets Packet in need
Reorder Buffer Size Traditional approaches –By experience –No formal method –Too pessimistic Our target –A general analytical model for worst-case reorder buffer size –A method to diminish the reorder buffer size Traffic splitting proportion
General Analysis S rb Size of reorder buffer D 1 Packet delay in path f 1 D 2 Packet delay in path f 2 △ t Packet injection interval Ideal case –No contention
Worst-case Reorder Buffer Size Definition 1
NC Model for Multi-path Routing Step 1 –Non-intersecting sub-flow identification –Traffic split proportion calculation
NC Model for Multi-path Routing Step 2 –Equivalent Service Curve (ESC) Calculation R: equivalent minimum service rate T: equivalent maximum processing latency  G. Du, C. Zhang, Z. Lu, A. Saggio, and M. Gao, “Worst-case performance analysis of 2-d mesh nocs using multi-path minimal routing,” in ISSS+CODES 2012.
NC Model for Multi-path Routing Step 3 –Calculation of Worst-case Reorder Buffer Size.
Total Size Mapping 2 –Reduction of maximum 36.50% (76 packets) –Average 29.20% (61packets) –Minimum 22.12% (46 packets)
Summary Our analytical model – Reduce worst case reorder buffer size To choose proper sub-flows pairs To alter traffic splitting proportion –Explore mapping effects Reorder buffer size Future work –To extend to more general cases
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