Time-transparent inter-processor connection reconfiguration in parallel systems based on multiple crossbar switches

Abstract

This chapter discusses a parallel program execution environment, based on dynamically reconfigurable connections between processors. The new proposed paradigm of inter-processor communication solves the problem of connection reconfiguration time overheads, which exists in current reconfigurable systems. These overheads cannot be completely eliminated by an increase of the speed of communication/reconfiguration hardware. However, they can be neutralized by a special method applied at the level of system architecture and at the level of program execution control, which is the look-ahead dynamic link connection reconfigurability. It is based on increasing the number of hardware resources used for dynamic link connection setting in the system and using them interchangeably in parallel for program execution and run-time look-ahead reconfiguration. A new program execution control strategy is included, in which application programs are partitioned into sections executed by clusters of processors whose mutual connections are prepared in advance. Inter-processor connections are set in advance in crossbar switches in parallel with program execution and remain fixed during section execution. The algorithm is presented, which determines at the compile time, the program schedule and partition into sections. It is based on list scheduling and iterative task clustering heuristics. The optimization criterion is the total execution time of a program partitioned into sections, including the cost of connection reconfiguration. This time is determined by program graph symbolic execution.