libpmem

Libpmem is a user-space library that provides low-level helpers for working with persistent memory (PM), including non-volatile memory devices such as Intel Optane DC Persistent Memory. It is part of the Persistent Memory Development Kit (PMDK), an open-source project that supplies libraries for building applications that persist data across crashes.

The library offers facilities to map files into memory with persistent semantics, inspect whether a region is backed by persistent memory, and perform persistence operations that flush CPU caches and apply memory fences so that writes reach non-volatile storage. Core routines include mapping and unmapping a file as a persistent memory region, and functions to persist or flush specified ranges of memory. Libpmem aims to provide a portable interface across supported platforms and file systems, abstracting away hardware details from the application.

Usage typically involves mapping a file using a function such as pmem_map_file, writing data to the returned pointer, and invoking a persistence helper like pmem_persist on the affected ranges before releasing or syncing the file descriptor. The library is designed to coexist with standard POSIX I/O and to cooperate with filesystem features that support direct access to persistent memory.

Libpmem is frequently used by higher-level PMDK components such as libpmemobj, libpmemblk, and libpmemlog, enabling applications to implement crash-consistent data structures and logs with minimal platform-specific code. It plays a foundational role in building robust, non-volatile data structures in environments with persistent memory.