Constant nc::types::MSGMNI

pub const MSGMNI: i32

MSGMNI, MSGMAX and MSGMNB are default values which can be modified by sysctl.

MSGMNI is the upper limit for the number of messages queues per namespace. It has been chosen to be as large possible without facilitating scenarios where userspace causes overflows when adjusting the limits via operations of the form retrieve current limit; add X; update limit".

MSGMNB is the default size of a new message queue. Non-root tasks can decrease the size with msgctl(IPC_SET), root tasks (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue size. The optimal value is application dependent. 16384 is used because it was always used (since 0.99.10)

MAXMAX is the maximum size of an individual message, it's a global (per-namespace) limit that applies for all message queues. It's set to 1/2 of MSGMNB, to ensure that at least two messages fit into the queue. This is also an arbitrary choice (since 2.6.0). <= IPCMNI, max # of msg queue identifiers