Generating Efficient Context-Switch Capable Circuits through Autonomous Design Flow

International audienceCommercial Off-the-Shelf (COTS) FPGAs are becoming increasingly powerful. In addition to their huge hardware resources, they are also integrated into complete systems on chips (SOCs), e.g. in the latest Xilinx Zynq or Altera Stratix platforms. However, cooperation between FPGAs and their surroundings, and the flexibility of hardware task management could still be improved. For instance, mechanisms have yet to be automated to allow multiuser approaches. A reconfigurable resource can be shared between applications or users only if it has a context-switch ability allowing applications to be paused and resumed in response to system demands. Here, we present a High-Level Synthesis (HLS) design flow producing a context-switch-capable circuit. The design flow manipulates the intermediate representation of a HLS tool to build the context extraction mechanism and to optimize performance for the circuit produced. The method is based on efficient checkpoint selection and insertion of a powerful scan-chain into the initial circuit. This scan-chain can extract flip-flops or memory content. Experiments with the system produced show that it has a low hardware overhead for many benchmark applications, and that the hardware added has a negligible impact on application performance. Comparison with current standard methods highlights the efficiency of our contributions