Enhancing data cache reliability by the addition of a small fully-associative replication cache

Abstract

Soft error conscious cache design is a necessity for reliable computing. ECC or parity-based integrity checking technique in use today either compromises performance for reliability or vice versa, and the N modular redundancy (NMR) scheme is too costly for microprocessors and applications with stringent cost constraint. This paper proposes a novel and cost-effective solution to enhance data reliability with minimum impact on performance. The idea is to add a small fully-associative cache to store the replica(s) of every write to the L1 data cache. The replicas can be used to detect and correct soft errors. The replication cache can also be used to increase performance by reducing the L1 data cache miss rate. Our experiments show that more than 97% read hits of the L1 data cache can find replicas available in a replication cache of 8 blocks.