3D FPGA resource management and fragmentation metric for hardware multitasking

This research work presents a novel proposal to get hardware multitasking in 3D FPGAs. Such architectures are still academic, but recent advances in 3D IC technologies allow foreseeing true 3D FPGAs in the near future. Starting from models for the 3D FPGA and for the tasks, an efficient technique for managing the 3D reconfigurable resources is proposed. This technique is based on a vertex-list structure in order to maintain information about the free space available on the FPGA at a given time moment. Moreover, a novel 3D fragmentation metric, based on cubeness of the free FPGA volume, is explained. And finally, several vertex-selection heuristics, a simpler one based on space adjacency and a more complex one based on space and time adjacency, are explained and their performance compared by some experiments.