Time-predictable Distributed Shared Memory for Multi-core Processors

Multi-core processors for real-time systems need to have a time-predictable way of communicating. The use of a single, external shared memory is the standard for multi-core processor communication. However, this solution is hardly time predictable. This paper presents a time-predictable solution for communication between cores, a distributed shared memory using a network-on-chip. The network-on-chip supports reading and writing data to and from distributed on-chip memory. This paper covers the implementation of time-predictable read requests on a network-on-chip. The network is implemented using statically scheduled, time-division multiplexing, enabling predictions for worst-case execution time. The implementation attempts to keep buffering as low as possible to obtain a small footprint. The solution has been implemented and successfully synthesized with a multi-core system on an FPGA. Finally, we show resource and performance measurements.