Advances in memory technology are promising the availability of byte-addressable persistent memory as an integral component of future computing platforms. This change has significant implications for software that has traditionally made a sharp distinction between durable and volatile storage. In this paper we describe a software-hardware architecture for persistent memory that provides atomicity and durability while simultaneously ensuring that fast paths through the cache, DRAM, and persistent memory layers are not slowed down, by burdensome buffering or double-copying requirements.