path: root/Documentation
diff options
authorManfred Spraul <manfred@colorfullife.com>2014-12-12 16:58:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-13 12:42:52 -0800
commit0050ee059f7fc86b1df2527aaa14ed5dc72f9973 (patch)
tree9fa11fd54259ed433d89b0a483e172b8e75d8f23 /Documentation
parentipc/sem.c: increase SEMMSL, SEMMNI, SEMOPM (diff)
ipc/msg: increase MSGMNI, remove scaling
SysV can be abused to allocate locked kernel memory. For most systems, a small limit doesn't make sense, see the discussion with regards to SHMMAX. Therefore: increase MSGMNI to the maximum supported. And: If we ignore the risk of locking too much memory, then an automatic scaling of MSGMNI doesn't make sense. Therefore the logic can be removed. The code preserves auto_msgmni to avoid breaking any user space applications that expect that the value exists. Notes: 1) If an administrator must limit the memory allocations, then he can set MSGMNI as necessary. Or he can disable sysv entirely (as e.g. done by Android). 2) MSGMAX and MSGMNB are intentionally not increased, as these values are used to control latency vs. throughput: If MSGMNB is large, then msgsnd() just returns and more messages can be queued before a task switch to a task that calls msgrcv() is forced. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index b5d0c8501a18..75511efefc64 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -116,10 +116,12 @@ set during run time.
-Enables/Disables automatic recomputing of msgmni upon memory add/remove
-or upon ipc namespace creation/removal (see the msgmni description
-above). Echoing "1" into this file enables msgmni automatic recomputing.
-Echoing "0" turns it off. auto_msgmni default value is 1.
+This variable has no effect and may be removed in future kernel
+releases. Reading it always returns 0.
+Up to Linux 3.17, it enabled/disabled automatic recomputing of msgmni
+upon memory add/remove or upon ipc namespace creation/removal.
+Echoing "1" into this file enabled msgmni automatic recomputing.
+Echoing "0" turned it off. auto_msgmni default value was 1.