Configuration for semaphores on Linux

[Brian Goad]

Ok I know this has been beaten to death, but I am not sure of what the settings on the server should be at this time. This is going to be long and I will appologize in advance for that.

Ok what I know about semaphores:

The kernel parameter sem consist of 4 tokens, respectivley SEMMSL, SEMMNS, SEMOPM and SEMMNS.

The value of SEMMNS should equal the result of SEMMSL multiplied by SEMMNI.

so to keep this easy:

SEMMSL = 10

SEMMNI = 2

SEMMNS = 20

I am not sure how these will effect the server either:

SEMOPM: Max ops per semop call….

My settings are:

SEMMNS = 62000

SEMMSL = 250

SEMMNI = 500

SEMOPM = 32

I do realize that 250 * 500 is greater than 62K. Just do not want to start making adjustments without a clearer picture.

Also I am sure that at some point there is a max, does anyone know how to determine what the max should be based on hardware specs?

What I am not sure about is how to determine what the settings should be based on the number of processes and threads on the box.

We are experiencing situations where the site panics because we can not open the semaphore.

Any ideas, or does anyone know of a algorithim to use for Cloverleaf to detemine how to set these values?

Any response will be appreciated and sorry if I am all over the place on this.

Brian

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