topic sem* parameters. in Operating System - HP-UX

sem* parameters.

Hell.Leader — Fri, 16 Nov 2001 00:27:39 GMT

What's stand for "semmni,semmnu,semmns,semume,semvmx" kernel parameters?

Re: sem* parameters.

A. Clay Stephenson — Fri, 16 Nov 2001 00:30:40 GMT

That is short for 'semaphore'. Specifically 'P' and 'V' semaphores that are used for process synchronization. The underlying principle is that the operations must be atomic. That is a request to lock a semaphore must also be able to lock the semaphore if it is free in one operation.

You can use, ipcs -sa command to look at current semaphores.

Clay

Re: sem* parameters.

Michael Tully — Fri, 16 Nov 2001 00:35:27 GMT

Hi,

*sem* stands for semaphores. You can see the meaning of these in /var/sam/boot.config.

To view the active ones, have a look at 'ipcs -s'

HTH
-Michael

Re: sem* parameters.

James R. Ferguson — Fri, 16 Nov 2001 01:39:15 GMT

Hi:

You may find some more information here (including the internal links to the individual kernel parameters):

http://docs.hp.com/hpux/onlinedocs/os/KCparam.SemaParmsOverview.html

Regards!

...JRF...

Re: sem* parameters.

Uday_S_Ankolekar — Fri, 16 Nov 2001 02:05:58 GMT

Hi,

These are semaphores. Some of the useful ipcs and ipcrm

ipcs -moba gives more details about shared memory
man ipcs for more information

The link James mentioned give you more details on semaphore settings
-USA..

Re: sem* parameters.

Sanjay_6 — Fri, 16 Nov 2001 02:20:18 GMT

Hi,

Take a look at the thread below for info on the kernel parameters,

http://docs.hp.com//hpux/onlinedocs/os/11i/kcparams/KCparams.OverviewAll.html

Hope this helps.

Regds

Re: sem* parameters.

Mary Ann Lipa — Fri, 16 Nov 2001 02:53:05 GMT

These are Configurable IPC-Semaphore Parameters

The following eight kernel parameters control System V IPC semaphore operating limits:

sema
(Series 700 only). Enable or disable IPC semaphores at system boot time.

semaem
Maximum value by which a semaphore can be changed in a semaphore "undo" operation.

semmap
Size of free-semaphores resource map for allocating requested sets of semaphores.

semmni
Maximum number of sets of IPC semaphores allowed on the system at any given time.

semmns
Total system-wide number of individual IPC semaphores available to system users.

semmnu
Maximum number processes that can have undo operations pending on any given IPC semaphore on the system.

semume
Maximum number of IPC semaphores that a given process can have undo operations pending on.

semvmx
Maximum value any given IPC semaphore is allowed to reach (prevents undetected overflow conditions).

For reference you can check it out at:
http://docs.hp.com/hpux/onlinedocs/os/KCparam.SemaphoreParamsList.html