how many undo structure am I using?

[kw_1]

I'm running 11i on rp7410. The kernel parameter semmnu is set to 384. My question is how can I find out how many semmnu the server is currently using. My application vendor is recommending a semmnu change to resolve a problem and I like to make sure we are truely close to 384 before I raise it.

[Steven E. Protter]

Collect performance data with the script I'm attaching.

SEP

[James Murtagh · Accepted solution]

Hi,

If you have a support contract ask your local RC to send you the seminfo utility, a contributed tool written by the labs. It will print various information on semaphores including the undo information.

You can also use the kernel debugger q4 to check this:

# ied q4 /stand/vmunix /dev/kmem
q4> load struct sem_undo from semunp next un_np max 4092
loaded 2 struct sem_undos as a linked list (stopped by null pointer)

So here i have 2 in use. My semmnu is set to 4092 - you would enter 384 here. If your application vendor is suggesting you raise this I would, simply to cover yourself in support issues. As memory capacities are generally so large these days keeping the kernel trimmed is not so important. You can check how much memory each of these structure takes:

q4> sizeof(struct sem_undo)
030 24 0x18

So this structure uses 24 bytes per entry.

Regards,

James.