In this paper we propose an online data-swapping (ODS) scheme to prolong PCM lifetime. The main idea behind ODS is dividing each line of memory to chunks of data and then swap incoming write request between predefined sets of chunks to reduce the number of bit flips.

In order to employ ODS in main memory, a circuitry is added between last level cache and main memory to perform the swapping process.

Hence, ODS requires the addition of metadata information for each chunk of data. Due to aggressive updates in such metadata information, they are stored in DRAM memory.

Experimental results carried out on PARSEC 3.0 [24] demonstrate that ODS improves the endurance of PCM based main memory endurance by about 48% and reduces its power consumption by approximately 46%.

However, the average memory access is increased by 1% due to the added circuitry.