From 8ebedd6c299447ffde86dd4453576a613875b928 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Sun, 17 Mar 2013 15:32:27 +0100 Subject: [PATCH] mq_overview.7: Document /proc/sys/fs/mqueue/msg_default Signed-off-by: Michael Kerrisk --- man7/mq_overview.7 | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/man7/mq_overview.7 b/man7/mq_overview.7 index ea0bceb0a..c5e5c7e3d 100644 --- a/man7/mq_overview.7 +++ b/man7/mq_overview.7 @@ -139,6 +139,33 @@ to link against the real-time library, The following interfaces can be used to limit the amount of kernel memory consumed by POSIX message queues: .TP +.IR /proc/sys/fs/mqueue/msg_default " (since Linux 3.5)" +This file defines the value used for a new queue's +.I mq_maxmsg +setting when the queue is created with a call to +.BR mq_open (3) +where +.I attr +is specified as NULL. +The default value for this file is 10. +The minimum and maximum are as for +.IR /proc/sys/fs/mqueue/msg_max . +If +.IR msg_default +exceeds +.IR msg_max , +a new queue's default +.I mq_maxmsg +value is capped to the +.I msg_max +limit. +Up until Linux 2.6.28, the default +.I mq_maxmsg +was 10; +from Linux 2.6.28 to Linux 3.4, the default was the value defined for the +.I msg_max +limit. +.TP .I /proc/sys/fs/mqueue/msg_max This file can be used to view and change the ceiling value for the maximum number of messages in a queue.