HP-UX 11i Version 2 Release Notes (October 2003)

General System Administration
System-V IPC Kernel Tunable Parameter (semmsl)
Chapter 4
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System-V IPC Kernel Tunable Parameter (semmsl)
The System-V IPC kernel tunable configuration parameter semmsl sets the maximum
number of semaphores per ID which can be grouped within a single System-V IPC
semaphore set.
Summary of Change
The minimum and default value of semmsl was 2048 on the HP-UX 11i v1 release. Its
minimum value is now 1; its default value is 2048, while its upper limit remains 10240.
Dynamic tune adjustments to semmsl may be done using SAM or the kernel
configuration command kctune (1M).
The value of semmsl can be increased or decreased dynamically.
Impact
The ability to select a smaller semmsl value allows you to further constrain application
use of kernel resources.
Compatibility
There are no compatibility issues.
Performance
Some applications which create a number of semaphore sets up to the semmsl maximum
may realize a performance improvement by being forced to spread the semaphores over
more semaphore sets, thereby reducing the contention associated with accessing
semaphores belonging to the same set.
Documentation
For further information, see the semmsl (5) manpage.
Obsolescence
Not applicable.
Update-UX
The update-ux command updates the HP-UX operating system to a newer version.
Update-UX is new to the HP-UX 11i v2 (B.11.23) release and allows an update from
HP-UX 11i v1.6 (B.11.22).