Direct I/O
Direct I/O is a method of performing input/output operations where data is transferred directly between application memory and storage devices without being cached by the operating system's page cache. This bypasses the kernel's caching layer, allowing applications to manage their own caching strategies for specific workloads. It is commonly used in database systems, high-performance computing, and applications requiring predictable I/O performance.
Developers should use Direct I/O when building applications that require consistent, low-latency I/O performance, such as databases (e.g., MySQL, PostgreSQL) or large-scale data processing systems, to avoid cache overhead and ensure data integrity. It is particularly useful for workloads where the application has better knowledge of access patterns than the OS, or when avoiding double buffering in memory is critical for efficiency.