Cache Miss Clustering for Banked Memory Systems

One of the previously-proposed techniques for reducing memory energy consumption is memory banking. The idea is to divide the memory space into multiple banks and place currently unused (idle) banks into a low-power operating mode. The prior studies - both hardware and software domain - in memory energy optimization via low-power modes do not take the data cache behavior explicitly into account. As a consequence, the energy savings achieved by these techniques can be unpredictable due to dynamic cache behavior at runtime. The main contribution of this paper is a compiler optimization, called the bank-aware cache miss clustering, that increases idle durations of memory banks, and as a result, enables better exploitation of available low-power capabilities supported by the memory system. This is because clustering cache misses helps to cluster cache hits as well, and this in turn increases bank idleness. We implemented our cache miss clustering approach within a compilation framework and tested it using seven array-intensive application codes. Our experiments show that cache miss clustering saves significant memory energy as a result of increased idle periods of memory banks