The Case for Associative DRAM Caches

In-package DRAM caches are a promising new development that may enable the continued scaling of main memory by facilitating the creation of multi-level memory systems that can effectively utilize dense non-volatile memory technologies. However, determining an appropriate storage scheme for the large amount of meta-data needed by these new caches has proven to be difficult. As a result, prior work has suggested that associativity, with its additional meta data requirements, may not be well suited for use in large in-package DRAM caches. This work makes the case that despite these problems, associativity is still a desirable feature for DRAM caches by demonstrating the benefits of associativity for a wide range of cache configurations and workloads.