Odd/Even Invert coding for phase change memory with thermal crosstalk

Abstract

Cloud based services demand a colossal amount of memory in order to satisfy their objectives. Phase-change memory (PCM) has emerged as one of the most promising memory technologies to feature in next generation memory systems. One of the key challenges of PCM is the limited number of writes that can be performed on memory cells also known as “write endurance”. In this paper we present a cost model which captures the asymmetry as well as disturb characteristics associated with write operations in PCMs. Moreover, we present an encoding architecture based on the proposed cost metric to allow the write operation to be performed using minimum cost. The proposed approach called “Odd/Even Invert” re-codes data based on selective inversion of even and/or odd bits to find minimum cost write operation that shall enhance cells lifetime. The proposed approach inquires a cost of only two extra bits regardless of the size of data word used, hence provides a cost effective approach to the problem. Experimental results and comparison with existing techniques on random data, real data, and memory traces from PERSEC benchmark suite, show the effectiveness and scalability of the proposed scheme.