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Semaphophe Waits

George Nikoloudis_1
Frequent Advisor

Semaphophe Waits

Dear all
From perfview I have counter called SEM_WAIT_PCT that is more than 15% Is there are a problem. I am attathing the Kernel parameters in case you need them. Maybe my kernel is oversized. I am running a V Class System 2500 8 GB Memory and 8 Processors.

thanks a lot
3 REPLIES
David Lodge
Trusted Contributor

Re: Semaphophe Waits

This is the average percentage of waits on semaphores in the OS...

It is not likely to be related to the kernel parameters it is more likely to do with the applications being run on the systems (if they use lots of semaphores for example) Chances are it indicates an application behaving badly - by setting a semaphore and not clearing it...

What software are you running - as some applications need more semaphores than others...

(Note to see the semaphores you have on your system use 'ipcs -s')

dave
George Nikoloudis_1
Frequent Advisor

Re: Semaphophe Waits

I am running ORACLE 8.1.7.2 and some custom applications.
David Lodge
Trusted Contributor

Re: Semaphophe Waits

It would probably be worth you doing an ipcs -s and seeing what is using the semaphores - just as a quick check oracle uses some semaphores but not many at a quick check it seems to be one per database.

I think the issue may be with your bespoke applications...

Another thing you can do is to use Glance and see how many processes are waiting for a semaphore and investigate those...

dave