Memory-Mapped I/O

Memory-Mapped I/O — A mechanism that maps file or device regions into a process address space so data can be accessed through ordinary memory operations.

Operating-System Context

Memory-mapped file I/O maps file regions into a process address space so ordinary memory accesses trigger demand paging of file-backed pages. It can reduce explicit read calls and share pages through the operating-system page cache for large read-only data, indexes, or selected IPC designs.

Resource Boundary

mmap is not a blanket zero-copy guarantee. Page faults, dirty-page writeback, address-space pressure, synchronization, and storage behavior remain part of the cost model.

Related Operating-System Concepts

• Page Fault
• Page Cache
• Zero Copy
• Virtual Memory