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authorStanislav Kinsbursky <skinsbursky@parallels.com>2013-01-04 15:34:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-01-04 16:11:45 -0800
commit03f595668017f1a1fb971c02fc37140bc6e7bb1c (patch)
tree3aa5c4b32b5fd396f0d74679548de8c09ca195a1 /Documentation
parent9afdacda0252fc1ddb7907728e878518edbcdfce (diff)
downloadlinux-03f595668017f1a1fb971c02fc37140bc6e7bb1c.tar.gz
ipc: add sysctl to specify desired next object id
Add 3 new variables and sysctls to tune them (by one "next_id" variable for messages, semaphores and shared memory respectively). This variable can be used to set desired id for next allocated IPC object. By default it's equal to -1 and old behaviour is preserved. If this variable is non-negative, then desired idr will be extracted from it and used as a start value to search for free IDR slot. Notes: 1) this patch doesn't guarantee that the new object will have desired id. So it's up to user space how to handle new object with wrong id. 2) After a sucessful id allocation attempt, "next_id" will be set back to -1 (if it was non-negative). [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/sysctl/kernel.txt19
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 2907ba6c360..51b953a1b14 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -38,6 +38,7 @@ show up in /proc/sys/kernel:
- l2cr [ PPC only ]
- modprobe ==> Documentation/debugging-modules.txt
- modules_disabled
+- msg_next_id [ sysv ipc ]
- msgmax
- msgmnb
- msgmni
@@ -62,7 +63,9 @@ show up in /proc/sys/kernel:
- rtsig-max
- rtsig-nr
- sem
+- sem_next_id [ sysv ipc ]
- sg-big-buff [ generic SCSI device (sg) ]
+- shm_next_id [ sysv ipc ]
- shm_rmid_forced
- shmall
- shmmax [ sysv ipc ]
@@ -320,6 +323,22 @@ to false.
==============================================================
+msg_next_id, sem_next_id, and shm_next_id:
+
+These three toggles allows to specify desired id for next allocated IPC
+object: message, semaphore or shared memory respectively.
+
+By default they are equal to -1, which means generic allocation logic.
+Possible values to set are in range {0..INT_MAX}.
+
+Notes:
+1) kernel doesn't guarantee, that new object will have desired id. So,
+it's up to userspace, how to handle an object with "wrong" id.
+2) Toggle with non-default value will be set back to -1 by kernel after
+successful IPC object allocation.
+
+==============================================================
+
nmi_watchdog:
Enables/Disables the NMI watchdog on x86 systems. When the value is