一种低开销的异构可变相联度二级Cache结构

V-Way Cache结构利用存储访问在组之间分布的不均匀性,根据需求动态调整组相联度,具有比传统Cache结构更有效的资源利用率。然而,V-Way Cache结构组相联度调整以增大Tag阵列容量为代价,增加了面积、功耗等开销,且Tag阵列利用率不高。对V-Way Cache结构进行优化,提出一种低开销的异构可变相联度Cache结构HV-Way Cache。HV-Way Cache采用异构Tag阵列组织,通过允许多个组共享Tag项资源以缩减Tag路容量;Tag项替换信息以组为单位组织,挑选最久没有被使用的项作为被替换项。使用Cacti和Simics模拟器进行模拟实验,结果表明HV-Way Cache结构能以很少的性能损失实现面积、功耗开销的极大降低。

A low-overhead heterogeneous variable way L2 Cache

Exploiting non uniform distribution of cache accesses among sets, V Way cache allows varying ways in sets according to the run time demands and outperforms conventional set associative cache in resource utilization. However, the tag array in V Way cache is expanded, inducing large area and power overhead. Considering that the tag array is under utilized in V Way cache, we propose a low overhead heterogeneous variable way cache, named HV Way cache. The HV Way cache adopts a heterogeneous tag array and cut down the capacity of tag ways by sets sharing in the same way. Maintaining tag replacement information in per set granularity, The HV Way cache selects the least recently used tag entries for eviction. Experiment results of Cacti and Simics simulators show that the HV Way cache brings down the latency, area and power overhead greatly at the expense of small performance loss.