1.5.5 Limis on Message Resources
Sizeof various structures:
- msqid_ds 52 /* 1 per message queue .. dynamic */
- msg 16 /* 1 for each message in system .. dynamic */
- msgbuf 8 /* allocated by user */
Limits
- MSGMNI : number of message queue identifiers ... policy.
- MSGMAX : max size of message.
Header and message space allocated on one page.
MSGMAX = (PAGE_SIZE - sizeof(struct msg)).
Implementation maximum MSGMAX = 4080.
- MSGMNB : default max size of a message queue ... policy.
The super-user can increase the size of a
queue beyond MSGMNB by a
msgctl
call.
Unused or unimplemented:
MSGTQL max number of message headers system-wide.
MSGPOOL total size in bytes of msg pool.