Configuration prefetching and reuse for preemptive hardware multitasking on partially reconfigurable FPGAs

Partially reconfigurable (PR) FPGAs enable preemptive hardware (HW) multitasking using PR regions (PRRs). To enable this multitasking, the HW task's partial bit-stream is downloaded to only the task's PRR, and only that PRR is reconfigured. Since only a small portion of the FPGA fabric is reconfigured, reconfiguration time is significantly reduced as compared to reconfiguring the entire fabric, however this time is not negligible. Reconfiguration time can be reduced/hidden using two techniques: configuration prefetching and configuration reuse. Even though these techniques can effectively reduce/hide reconfiguration overhead, prior works in preemptive HW multitasking did not use these techniques. To the best of our knowledge, no prior work evaluated physical implementations of these techniques on PR FPGAs, which precludes consideration of physical-implementation-specific details, such as delays in accessing bitstreams, speed limitations during reconfiguration, etc. In this work, we present a novel implementation of configuration prefetching and reuse for preemptive HW multitasking on a Virtex-5 FPGA, however, our established fundamentals are device-family independent.