msgssz

msgssz specifies the message segment size that is to be used when allocating message space in message queues.

Acceptable Values:

Minimum
1
Maximum
Memory limited
Default
8 bytes

Specify integer value. For more information, see Specifying Parameter Values.

Description

msgseg, multiplied by msgssz, defines the total amount of shared-memory message space that can exist for all message queues, system-wide (not including message header space).

msgssz specifies the size, in bytes, of the segments of memory space to be allocated for storing IPC messages. Space for new messages is created by allocating one or more message segments containing msgssz bytes each as required to hold the entire message.

msgmnb specifies how many bytes of storage space are allowed in each message queue.

Queue Space and Fragmentation

Total space available for all message queues is defined by the product of msgseg * msgssz. Changing the ratio of these two values changes how message space is fragmented for any given messaging usage pattern.

Related Parameters

(msgseg times msgssz) must be greater than or equal to msgmax

Additional Information