From 03f595668017f1a1fb971c02fc37140bc6e7bb1c Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Fri, 4 Jan 2013 15:34:50 -0800 Subject: 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 Cc: Serge Hallyn Cc: "Eric W. Biederman" Cc: Pavel Emelyanov Cc: Al Viro Cc: KOSAKI Motohiro Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/sysctl/kernel.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'Documentation') 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 -- cgit v1.2.3