A Cache Reconfiguration Approach for Saving Leakage and Refresh Energy in Embedded DRAM Caches

摘要

In recent years, the size and leakage energy consumption of large last levelcaches (LLCs) has increased. To address this, embedded DRAM (eDRAM) caches havebeen considered which have lower leakage energy consumption; however eDRAMcaches consume a significant amount of energy in the form of refresh energy. Inthis paper, we present a technique for saving both leakage and refresh energyin eDRAM caches. We use dynamic cache reconfiguration approach to intelligentlyturn-off part of the cache to save leakage energy and refresh only valid dataof the active (i.e. not turned-off) cache to save refresh energy. We evaluateour technique using an x86-64 simulator and SPEC2006 benchmarks and compare itwith a recently proposed technique for saving refresh energy, named Refrint.The experiments have shown that our technique provides better performance andenergy efficiency than Refrint. Using our technique, for a 2MB LLC and 40micro-seconds eDRAM refresh period, the average saving in energy over eDRAMbaseline (which periodically refreshes all cache lines) is 22.8%.