From cef0184c115e5e4e10498f6548d9526465e72478 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Thu, 31 May 2012 16:26:33 -0700 Subject: mqueue: separate mqueue default value from maximum value Commit b231cca4381e ("message queues: increase range limits") changed mqueue default value when attr parameter is specified NULL from hard coded value to fs.mqueue.{msg,msgsize}_max sysctl value. This made large side effect. When user need to use two mqueue applications 1) using !NULL attr parameter and it require big message size and 2) using NULL attr parameter and only need small size message, app (1) require to raise fs.mqueue.msgsize_max and app (2) consume large memory size even though it doesn't need. Doug Ledford propsed to switch back it to static hard coded value. However it also has a compatibility problem. Some applications might started depend on the default value is tunable. The solution is to separate default value from maximum value. Signed-off-by: KOSAKI Motohiro Signed-off-by: Doug Ledford Acked-by: Doug Ledford Acked-by: Joe Korty Cc: Amerigo Wang Acked-by: Serge E. Hallyn Cc: Jiri Slaby Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/sysctl/fs.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt index 88fd7f5c8dcd..13d6166d7a27 100644 --- a/Documentation/sysctl/fs.txt +++ b/Documentation/sysctl/fs.txt @@ -225,6 +225,13 @@ a queue must be less or equal then msg_max. maximum message size value (it is every message queue's attribute set during its creation). +/proc/sys/fs/mqueue/msg_default is a read/write file for setting/getting the +default number of messages in a queue value if attr parameter of mq_open(2) is +NULL. If it exceed msg_max, the default value is initialized msg_max. + +/proc/sys/fs/mqueue/msgsize_default is a read/write file for setting/getting +the default message size value if attr parameter of mq_open(2) is NULL. If it +exceed msgsize_max, the default value is initialized msgsize_max. 4. /proc/sys/fs/epoll - Configuration options for the epoll interface -------------------------------------------------------- -- cgit v1.2.3-59-g8ed1b