Concurrent I/O

Concurrent I/O (VX_CONCURRENT) allows multiple processes to read from or write to the same file without blocking other read(2) or write(2) calls. POSIX semantics requires read and write calls to be serialized on a file with other read and write calls. With POSIX semantics, a read call either reads the data before or after the write call occurred. With the VX_CONCURRENT advisory set, the read and write operations are not serialized as in the case of a character device. This advisory is generally used by applications that require high performance for accessing data and do not perform overlapping writes to the same file. It is the responsibility of the application or the running threads to coordinate the write activities to the same file when using Concurrent I/O.

Concurrent I/O can be enabled in the following ways: