Performance, energy, and reliability tradeoffs in replicating hot cache lines

The importance of L1 data caches makes their performance, power consumption, and data integrity characteristics extremely critical in embedded systems design. We examine these issues in the context of a mechanism that tries to enhance data cache reliability by replicating cache lines (blocks) in active use. When replicating data cache lines, it is important to not evict other lines that may be needed or to not incur very high power consumption. We evaluate the tradeoffs between these three goals (reliability, energy, and performance) by modulating two important parameters, namely, the hot-block threshold and the dead-block threshold. We show that having a hot-block threshold in the range of 10-1000 cycles can provide good reliability characteristics, without compromising on performance or power. At the same time, our results indicate that one could use aggressive dead-block thresholds to provide leakage power savings without compromising on the performance and reliability characteristics. The results from this paper can be used to design power, performance, and reliability enhanced cache architectures.