Thermal management of manycore systems with silicon-photonic networks

Silicon-photonic network-on-chips (NoCs) provide high bandwidth density; therefore, they are promising candidates to replace electrical NoCs in manycore systems. The silicon-photonic NoCs, however, are sensitive to the temperature gradients that typically occur on the chip, and hence, require proactive thermal management. This paper first provides a design space exploration of silicon-photonic networks in manycore systems and quantifies the performance impact of the temperature gradients for various network bandwidths. The paper then introduces a novel job allocation technique that minimizes the temperature gradients among the ring modulators/filters to improve the application performance. Experimental results for a single-chip 256-core system demonstrate that our policy is able to maintain the maximum network bandwidth. Compared to existing workload allocation policies, the proposed policy improves system performance by up to 26.1% when running a single application and 18.3% for multi-program scenarios.