Performance analysis of arbitration policies for SoC communication architectures

As technology scales toward deep submicron, the integration of a large number of IP blocks on the same silicon die is becoming technically feasible, thus enabling large-scale parallel computations, such as those required for multimedia workloads. The communication architecture is becoming the bottleneck for these multiprocessor Systems-on-Chip (SoC), and efficient contention resolution schemes for managing simultaneous access requests to the shared communication resources are required to prevent system performance degradation. The contribution of this work is to analyze the impact on multiprocessor SoC performance of different bus arbitration policies under different communication patterns, showing the distinctive features of each policy and the strong correlation of their effectiveness with the communication requirements of the applications. Beyond traditional arbitration schemes such as round robin and TDMA, another policy is considered that periodically allocates a temporal slot for contention-free bus utilization to a processor which needs fixed predictable bandwidth for the correct execution of its time-critical task. The results are derived on a complete and scalable multiprocessor SoC simulation platform based on SystemC, whose software support includes a complete embedded multiprocessor OS (RTEMS). The communication architecture is AMBA compliant, and we exploit the flexibility of this multi-master commercial standard, which does not specify the arbitration algorithm, to implement the explored contention resolution schemes.