COREFAB: Concurrent Reconfigurable Fabric Utilization in Heterogeneous Multi-Core Systems

Application-specific accelerators may provide considerable speedup in single-core systems with a runtime-reconfigurable fabric (for simplicity called "fabric" in the following). A reconfigurable core, i.e. processor core pipeline coupled to a fabric, can be integrated along with regular general purpose processor cores (GPPs) into a reconfigurable multi-core system with widely improved system performance. As most applications only use a fraction of the available fabric at a time, making the fabric usable by the GPPs (in addition to the reconfigurable core) in such a multi-core system is desirable. Existing work focused on algorithms that decide the amount of fabric that is assigned to each core in a multi-core system. However, when multiple cores access the fabric simultaneously, they are either limited to serialized fabric access or, when parallel access is supported, the size of the fabric share assigned to a core is inflexible and tends to be over-or undersized for the running application, thereby not efficiently utilizing the fabric. We propose a novel approach that allows GPPs to access the fabric of the reconfigurable core and that enables concurrent fabric utilization on-the-fly through merging fabric accesses from different cores at runtime. Compared to state-of-the art, our approach improves performance of the GPPs in a reconfigurable multi-core system by 1.3x on average, without reducing the performance of the reconfigurable core.