Relieving Write Disturbance for Phase Change Memory With RESET-Aware Data Encoding

The write disturbance (WD) problem is becoming increasingly severe in PCM due to the continuous scaling down of memory technology. Previous studies have attempted to transform WD-vulnerable data patterns of the new data to alleviate the WD problem. However, through a wide spectrum of real-world benchmarks, we have discovered that simply transforming WD-vulnerable data patterns does not proportionally reduce (or may even increase) WD errors. To address this issue, we present
ResEnc
, a RESET-aware data encoding scheme that reduces RESET operations to mitigate the WD problem in both wordlines and bitlines for PCM. It dynamically establishes a mask word for each block for data encoding and adaptively selects an appropriate encoding granularity based on the diverse write patterns.
ResEnc
finally reassigns the mask words of unchanged blocks to changed blocks for exploring a further reduction of WD errors. Extensive experiments show that
ResEnc
can reduce 16.8-87.0% of WD errors, shorten 5.6-39.6% of write latency, and save 7.0-43.1% of write energy for PCM.