IPC - shared memory and semaphores

[screwloose]

Are the IPC facilities of shared memory, semaphores, and message queues affected by the amount of real memory in a server?

Say you have to set semsys:seminfo_semmns to 1500 for one application and another application requires a value of 1400. Does/will over allocation of the shm, sem, and msg parameters cause a system problem?

I am sure that resources are allocated based on the settings, so is it possible to set them too high?

Thanks!

 

[Mike042]

Yes, "IPC facilities of shared memory, ..." are affected by the amount of real memory. Most noticeable in systems with smaller amounts of memory (say less than 1024 megs).

If several applications want differing values for the same system parameter (eg: seminfo_semmns) then set it to the largest value requested. Choosing values that are hugely above that which are suggested could obviously cause problems to a system.

Before making changes in /etc/system read the "Solaris Tunable Parameters Reference Manual" (Chapter 2). Can be founds on Sun's website docs.sun.com to see a description, the range of values, usage etc for each parameter.

I hope that helps.

Mike

 

[screwloose]

thanks.