Tunable Kernel Parameters

Interprocess Communication (IPC) Subsystem
IPC Parameter Summary
Chapter 5
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IPC Parameter Summary
See also “How to Specify Configurable Parameter Values” on page 13.
Message Parameter Summary
The following parameters control allocation of space for messages.
See also “Overview of Message Queue Operations” on page 35.
Semaphore Parameter Summary
The following kernel parameters control System V IPC semaphore operating limits.
See also “Overview of Semaphore Operations” on page 37.
IPC: Message mesg Enable or disable IPC messages at system boot time.
Manpage: mesg (5).
IPC: Message msgmap Size of free-space resource map for allocating shared
memory space for messages. Manpage: msgmap (5).
IPC: Message msgmax System-wide maximum size (in bytes) for individual
messages. Manpage: msgmax (5).
IPC: Message msgmnb Maximum combined size (in bytes) of all messages that
can be queued simultaneously in a message queue.
Manpage: msgmnb (5).
IPC: Message msgmni Maximum number of message queues allowed on the
system at any given time. Manpage: msgmni (5).
IPC: Message msgseg Maximum number of message segments that can exist on
the system. Manpage: msgseg (5).
IPC: Message msgssz Message segment size in bytes. Manpage: msgssz (5).
IPC: Message msgtql Maximum number of messages that can exist on the
system at any given time. Manpage: msgtql (5).
IPC: Semaphore sema Enable or disable IPC semaphores at system boot time.
Manpage: sema (5).
IPC: Semaphore semaem Maximum value by which a semaphore can be changed in
a semaphore “undo” operation. Manpage: semaem (5).
IPC: Semaphore semmni Maximum number of sets of IPC semaphores allowed on
the system at any one time. Manpage: semmni (5).
IPC: Semaphore semmns Maximum number of individual IPC semaphores available
to system users, system-wide. Manpage: semmns (5).
IPC: Semaphore semmnu Maximum number of processes that can have undo
operations pending on any given IPC semaphore on the
system. Manpage: semmnu (5).