IPC semaphores

Jonathan Williams · *nix forums addict Joined: 07 May 2002 Posts: 88

Ok, I don't really know anything about semaphores, but I do know that our system is running out of them. If we use ipcs to look at the semaphores it shows that 498 are in use, and the kernel is set to only use 512. We want to increase this number, but are unsure how to do this. We were told by Envoy to increase the size of the sem-mni and sem-mns values. So we looked into this, and are now even more confused. I can't find any reference to "sem_mns" anywhere--it's not in any of the man pages or in dxkerneltuner. So what is this attribute, and where do you change it? And the "sem-mni" attribute is set to 400 at boot time, but the current value is 512. Where did this current value come from? The /etc/sysconfigtab file says 400 as well. So I'm wondering if I increase the sem-mni to something else and boot it, will the 512 number come back? Also, what would be a good number to change it to?
We don't usually have this many semaphores at all, only when we experience some sort of network issue, and then the semaphores go up. Any info would be great...I hope this makes some sort of sense to someone out there.
BTW: system= ES45 Tru64 5.1a

Jonathan Williams
Unix Systems Administrator
The Shubert Organization, Inc.

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