Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
HP-UX Reference > S

semmsl(5)

Tunable Kernel Parameters
HP-UX 11i Version 3: February 2007
» 

Technical documentation

» Feedback
Content starts here

 » Table of Contents

 » Index

NAME

semmsl — maximum number of System V IPC semaphores per identifier

VALUES

Failsafe

2048

Default

2048

Allowed values

Minimum: 1

Maximum: 10240

DESCRIPTION

The semmsl tunable specifies the maximum number of individual System V IPC semaphores per semaphore identifier (ID).

If an application attempts to exceed this limit, it will receive an EINVAL error from semget().

For more information about System V semaphores, refer to the Overview section of the sema(5) manpage.

Who Is Expected to Change This Tunable?

Anyone.

When Should the Value of This Tunable Be Raised?

If applications require a larger number of semaphores per ID.

When Should the Value of This Tunable Be Lowered?

If application requirements for semaphores per ID has decreased or there is a need to protect against ill-behaved applications.

What Other Tunable Values Should Be Changed at the Same Time?

All the System V semaphore tunables are interrelated and should not be treated as independent variables. The tunables must be evaluated as a system to ensure they reflect the application requirements. The semaphore tunables include semaem, semmni, semmns, semmnu, semmsl, semume, semvmx, and sysv_hash_locks. Specifically, a change in the semmsl tunable may require a change in the semmns tunable.

WARNINGS

All HP-UX kernel tunable parameters are release specific. This parameter may be removed or have its meaning changed in future releases of HP-UX.

Prior to HP-UX 11i Version 1 the maximum number of semaphores per ID was an undocumented constant 2048 in the header file sys/sem.h. Typically applications do not depend upon this limitation. For those that were compiled with the old constant, semmsl tunable values higher than 2048 will generally not be a problem. However, semmsl tunable values lower than 2048 may cause other such applications to fail. These should be recoded to obtain the current semmsl value from pstat_getipc(2).

Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parameter values. After installation, some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tunable values, consult the documentation for the kernel software being installed. For information about optional kernel software that was factory installed on your system, see HP-UX Release Notes at http://docs.hp.com.

AUTHOR

semmsl was developed by AT&T.

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© 1983-2007 Hewlett-Packard Development Company, L.P.