An evaluation on a set of memory-intensive
workloads shows that the unprotected lifetime
of PCM-based main memory can last
only an average of 171 days. Although Lee
et al. track written cache lines and written
cache words to implement partial writes
and reduce wear,2 fine-grained schemes at
the bit level might be more effective. Moreover,
combining wear reduction with wear
leveling can address low lifetimes arising
from write locality. Here, we introduce a hierarchical
set of techniques that both reduce
and level wear to improve the lifetime of
PCM-based main memory to more than
20 years on average.