同时基于预知信息和预测机制的SDRAM动态页策略

A dynamic SDRAM page policy based on advance information and prediction mechanism

提出一种同时基于预知信息和预测机制的SDRAM新型动态页策略。该策略可充分利用待处理访存请求的地址信息,能对后续页命中情况进行精确判断;而当没有待处理访存请求可预知时,则利用所记录的历史信息对后续页命中情况进行预测,以最大程度地选择最合适的页策略。分析证明该策略的硬件实现代价很小。实验证实三类主要的基于预知信息的动态页策略之间的性能差异较小,均能获得较理想的访存带宽,最好情况下,实际访存带宽可提升42%。其中,对于绝大多数测试激励,同时基于预知信息和预测机制的新型动态页策略的性能均为最优或接近最优,适应范围最广。

We present a novel dynamic SDRAM page policy based on prediction mechanism and ad- vance information. The policy makes full use of the addresses of memory accesses to accurately deter mine whether the next memory access is a page hit or not. If there is not a pending memory access, the policy predicts whether a page hit happens or not according to history records. Theoretical analysis shows that the policy can be easily implemented at low hardware cost. Experimental results confirm that all the three main categories of dynamic page policies based on advance information achieve the desired memory bandwidth. Under the best circumstances, the actual memory bandwidth is improved by 42 %. Among the three policies, the policy based on both prediction mechanism and advance information is the best.