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authorStanislav Kinsbursky2013-01-04 17:34:50 -0600
committerLinus Torvalds2013-01-04 18:11:45 -0600
commit03f595668017f1a1fb971c02fc37140bc6e7bb1c (patch)
tree3aa5c4b32b5fd396f0d74679548de8c09ca195a1 /Documentation
parent9afdacda0252fc1ddb7907728e878518edbcdfce (diff)
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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 2907ba6c3607..51b953a1b149 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -38,6 +38,7 @@ show up in /proc/sys/kernel:
38- l2cr [ PPC only ] 38- l2cr [ PPC only ]
39- modprobe ==> Documentation/debugging-modules.txt 39- modprobe ==> Documentation/debugging-modules.txt
40- modules_disabled 40- modules_disabled
41- msg_next_id [ sysv ipc ]
41- msgmax 42- msgmax
42- msgmnb 43- msgmnb
43- msgmni 44- msgmni
@@ -62,7 +63,9 @@ show up in /proc/sys/kernel:
62- rtsig-max 63- rtsig-max
63- rtsig-nr 64- rtsig-nr
64- sem 65- sem
66- sem_next_id [ sysv ipc ]
65- sg-big-buff [ generic SCSI device (sg) ] 67- sg-big-buff [ generic SCSI device (sg) ]
68- shm_next_id [ sysv ipc ]
66- shm_rmid_forced 69- shm_rmid_forced
67- shmall 70- shmall
68- shmmax [ sysv ipc ] 71- shmmax [ sysv ipc ]
@@ -320,6 +323,22 @@ to false.
320 323
321============================================================== 324==============================================================
322 325
326msg_next_id, sem_next_id, and shm_next_id:
327
328These three toggles allows to specify desired id for next allocated IPC
329object: message, semaphore or shared memory respectively.
330
331By default they are equal to -1, which means generic allocation logic.
332Possible values to set are in range {0..INT_MAX}.
333
334Notes:
3351) kernel doesn't guarantee, that new object will have desired id. So,
336it's up to userspace, how to handle an object with "wrong" id.
3372) Toggle with non-default value will be set back to -1 by kernel after
338successful IPC object allocation.
339
340==============================================================
341
323nmi_watchdog: 342nmi_watchdog:
324 343
325Enables/Disables the NMI watchdog on x86 systems. When the value is 344Enables/Disables the NMI watchdog on x86 systems. When the value is