1. Computer Architecture SIMD Ola Flygt Växjö University http://w3.msi.vxu.se/users/ofl/ Ola.Flygt@msi.vxu.se +46 470 70 86 49

2. Outline  Design space  Granularity  Connectivity  Processor complexity  Local Anotomy  Fine grained architectures  Course grained architectures CH01

3. A typical SIMD system

4. The development of SIMD systems

5. Design space  There are several factors to consider when designing a SIMD. The most important ones are:  Granularity  Connectivity  Complexity of processing element  Local autonomy

6. Granularity mapping data to PEs

7. Granularity Fine to coarse grain

8. Connectivity Not all the types of connectivity for data parallel arch. are used in SIMD arch.

9. Performance of interconnection networks  There are several important parameters in an interconnection network  Diameter, the shortest path between the two most distant nodes  Bandwidth, how many data exchanges simultaneous in the network  Blocking, how many exchanges are blocked

10. Performance of interconnection networks N=128*128 1 256 28 14 1 N=128*128 1 16384 28 14 16384

11. Processor complexity  The design space for processor precision  Single bit – fine grained, mainly for image processing  Integer – general computing  Floating point – Coarse grain, scientific computing  Fine grained -> more PEs

12. Local autonomy

13. Fine grained SIMD The MPP system

14. Fine grained SIMD The MPP processing element

15. Fine grained SIMD The MPP integrated circuit

16. Coarse grained SIMD The CM5 processing element

17. Coarse grained SIMD The CM5 fat tree connectivity

18. Coarse grained SIMD The CM5 system parameters