Design and implementation of a plesiochronous multi-core 4x4 network-on-chip FPGA platform with MPI HAL support

The Multi-Core NoC is a 4 by 4 Mesh NoC targeted for Altera FPGAs. It implements a deflective routing policy and is used to connect sixteen NIOS II processors. Each NIOS II is connected to the NoC via an address-mapped Resource Network Interface. The Multi-Core NoC is implemented on four separate Altera Stratix II FPGA boards, each hosting a Quad-Core NoC, which operates on a local 50 MHz clock.

It has an onboard throughput of 650 Mbps (12.5 MFlit/s), and uses 28% of the LUs, 18% of the ALUTs, 22 % of the dedicated registers and 31% of the total memory blocks of a Stratix II FPGA. Asynchronous clock bridges, with a throughput of 50 Mbps (~1MFlit/s), are used for the inter-board communication.

Application programs use an MPI compatible Hardware Abstraction Layer (HAL) to communicate with the Resource Network Interface of the NoC. The RNI sets up message transfer, with a maximum length of 512 bytes, and sends flits with the size of 32 bit data plus 20 bit headers through the network. The MPI is the bottleneck of the system; it takes 46 us (43.4 kPackets/s) to send a minimum-sized packet through the protocol stack to a near neighbour and bounce it back to the original application.

The bounce-back time for a far neighbour is 56 us.