Fault-adaptive routing

Transcription

1 Fault-adaptive routing Presenter: Zaheer Ahmed Supervisor: Adan Kohler Reviewers: Prof. Dr. M. Radetzki Prof. Dr. H.-J. Wunderlich Date: 30-June /2/2009

2 Agenda Motivation Fundamentals of Routing & Blocks Models xtended X-Y Routing and xtended MCC Fault Model Force Directed Wormhole Routing Conclusion 2

3 Agenda Motivation Fundamentals of Routing & Blocks Models xtended X-Y Routing and xtended MCC Fault Model Force Directed Wormhole Routing Conclusion 3

4 Motivation Fault Adaptive Routing Ability to operate in the event of failure of component Low Communication latency High Throughput 4

5 Agenda Motivation Fundamentals of Routing & Fault Block Models xtended X-Y Routing and xtended MCC Fault Model Force Directed Wormhole Routing Conclusion 5

6 2D mesh Topology Consist of n n Node Address of each Switch is defined as (X,Y) where x and y in range of {0,1,2,.,n-1} ach inner node have 4 neighbors IP core IP core IP core IP core IP core IP core Corner and boundary have 2 and 3 neighbors respectively IP core IP core IP core NoC Switch IP: Intellectual Property IP core 6

7 Types of Routing Algorithm Deterministic Routing Algorithm Uses only one predefine path to destination can be minimal or non-minimal Adaptive Routing Algorithm Can use multiple path to destination based on conditions Can be minimal or non-minimal 7

8 X-Y Routing Algorithm Deterministic Routing There two Steps to destination Packet travel x-dimension until x offset zero Packet travel y-dimension until y offset zero 8

9 X-Y Routing Algorithm Cont Cannot tolerate even a single fault 9

10 Odd-ven Turn Model SW and NW turns are Forbidden in Odd Column SW and NW turns are Forbidden in ven Column S: South-ast N: ast-north NW: North-West WS: West-South [Source: Glass, C.J.; Ni, L.M., "The Turn Model for Adaptive Routing," Computer Arch Proceedings., The 19th Annual International Symposium, pp , 1992] 10

11 Fault Blocks Fault block is a set of nodes excluded from routing Fault block consist of following nodes Faulty Nodes Unsafe Nodes Unreachable Nodes 11

12 Agenda Motivation Fundamentals of Routing & Fault Blocks Models xtended X-Y Routing and xtended MCC Fault Model Force Directed Wormhole Routing Conclusion MCC: Minimal Connected Components 12

13 xtended X-Y Routing Implements Odd-ven Turn Model Algorithm Consist of Two phases Phase1: Travel along X-dimension Phase2: Travel along Y-dimension ach Phase has two modes Normal mode: Follows X-Y Routing Abnormal mode: Traffic diversion is case of hitting faulty node [Source: J. Wu and D. Wang. Fault tolerant and Deadlock-Free routing in 2-D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 13

14 xtended X-Y Routing Cont Phase1 Abnormal mode Packet hit faulty block travel in west in even column O O Phase2 Abnormal mode Packet hit from ast and West to faulty block reroute in Odd and ven Column respectively O O [Source: J. Wu and D. Wang. Fault tolerant and Deadlock-Free routing in 2-D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 14

15 xtended X-Y Routing Cont [Source: J. Wu and D. Wang. Fault tolerant and Deadlock-Free routing in 2- D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 15

16 Minimal Connected Component Fault Block Produces Rectilinear Polygon Shape Source consider at Origin Nodes are labeled as: Useless, if north and east nodes are faulty Can t Reach, if south and west nodes are faulty MCC: Minimal Connected Component 16

17 MCC Fault Block Cont.. Less no. of nodes are included than Rectangular Blocks D S MCC: Minimal Connected Component [Source: J. Wu and D. Wang. Fault tolerant and Deadlock-Free routing in 2-D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 17

18 xtended Minimal Connected Component Merge Two MCC Blocks Facilitate Odd-ven Turn Model MCC: Minimal Connected Components [Source: J. Wu and D. Wang. Fault tolerant and Deadlock- Free routing in 2-D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 18

19 xtended X-Y Routing with xtended MCC Blocks Phase1: packet travel in even Column for North and South bound Phase2: Routed clockwise for I and III quadrant Routed anticlockwise for II and IV quadrant (a) (b) [Source: J. Wu and D. Wang. Fault tolerant and Deadlock- Free routing in 2-D Meshes using Rectilinear-Monotone Polygonal Fault blocks in Proceedings. International Conference on Parallel Processing, 2002, pp ] 19

20 Agenda Motivation Fundamentals of Routing & Fault Blocks Models xtended X-Y Routing and xtended MCC Fault Model Force Directed Wormhole Routing Conclusion MCC: Minimal Connected Components 20

21 Force Directed Wormhole Routing Algorithm Based on Distance Vector Routing Routing Decision based on routing Tables and buffer status of its neighbor Network Initialize with building routing table 21

22 Building Routing Table ach switch send routing flit to its neighbors If a shorter path received, update routing table D Mesh 5 8 Port North South ast West Number of hops to Number of hops to Number of hops to Number of hops to Number of hops to Number of hops to Number of hops to Number of hops to Number of hops to Routing table of switch 4 in 3 3 Mesh [Source: T. Schönwald, J. Zimmermann, O. Bringmann and W. Rosentiel. Fully adaptive Fault-Tolerant Routing Algorithm for Network-on-Chip Architectures, Digital System Design Architectures, Methods and Tools, uromicro Conference, Aug 2007 ] 22

23 Routing Packets D=3 D=3 Answer 7 Answer 8 Confirm Address 5 D=0 Answer Address Address 3 5 Confirm Others 8 [Source: T. Schönwald, J. Zimmermann, O. Bringmann and W. Rosentiel. Fully adaptive Fault-Tolerant Routing Algorithm for Network-on-Chip Architectures, Digital System Design Architectures, Methods and Tools, uromicro Conference, Aug 2007 ] 23

24 Load Balancing Avoid Network Congestion Penalties are use to avoid overload links Penalty= PAYLOAD_LNGTH no. of Flits sent Distance= α*hopcounttodestination + β*penalty Port North South ast West Penalty switch (0,0) Penalty switch (1,0) Penalty switch (1,1) Penalty switch (1,2) Penalty switch (2,2) Communication between switch 7 and Switch D Mesh Penalty switch (2,6) Penalty table of switch 4 in 3 3 Mesh 24

25 Fault Tolerance If a switch doesn t receive ANSWR flit node will be assume faulty D S 5 [Source: T. Schönwald, J. Zimmermann, O. Bringmann and W. Rosentiel. Fully adaptive Fault-Tolerant Routing Algorithm for Network-on-Chip Architectures, Digital System Design Architectures, Methods and Tools, uromicro Conference, Aug 2007 ] 25

26 Conclusion xt. XY Routing with MCC Blocks Less Memory Overheads Feasible for Large Meshes Create Hot Spot FDWR Algorithm Large Memory Requirements Not Feasible for Large Meshes Load Balancing to avoid Hot Spot MCC: Minimal Connected Component FDWR: Force Directed Wormhole Routing 26

27 Thank you for your attention! 7/2/2009