Jin Woo Ahn , Hong Jun Choi , Jong Myon Kim , Cheol Hong Kim

The KIPS Transactions:PartA, Vol. 19, No. 2, pp. 77-84, Apr. 2012
10.3745/KIPSTA.2012.19.2.77,   PDF Download:

Abstract

Speculative execution for improving instruction-level parallelism is widely used in high-performance processors. In the speculative execution technique, the most important factor is the accuracy of branch predictor. Unfortunately, complex branch predictors for improving the accuracy can cause serious thermal problems in 3Dmulticore processors. Thermal problems have negative impact on the processor performance. This paper analyzes two methods to solve the thermal problems in the branch predictor of 3D multi-core processors. First method is dynamic thermal management which turns off the execution of the branch predictor when the temperature of the branch predictor exceeds the threshold. Second method is thermal-aware branch predictor placement policy by considering each layer`s temperature in 3D multi-core processors. According to our evaluation, the branch predictor placement policy shows that average temperature is 87.69℃, and average maximum temperature gradient is 11.17℃. And, dynamic thermal management shows that average temperature is 89.64℃ and average maximum temperature gradient is 17.62℃. Proposed branch predictor placement policy has superior thermal efficiency than the dynamic thermal management. In the perspective of performance, the proposed branch predictor placement policy degrades the performance by 3.61%, while the dynamic thermal management degrades the performance by 27.66%.

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