Kernel tunables and memory allocation

[Mathieu P.]

Hello,

Is there a kernel tunable to allow a specific application to use a determined amount of memory, is their a maximum an application can allocate ? I'm also thinking performance wise - should I use any guideline not to "over-allocate" memory segments and maybe lose performance elsewhere?

Oh and, how can I determine how big is a memory segment !?

Thanks in advance ... !

[Tim Nelson]

maxdsiz
maxtsiz
maxsziz

and their 64 bit counterparts.

user usage of these maximums can be controlled by ulimit

These tunables are limits not pre-allocations

[Bill Hassell]

The kernel tunables affect *ALL* programs. For a specific application, you can start the application with a shell wrapper script that uses ulimit to set a particular value. However, the vast majority of programs do not behave well (as in: crash) when they do not get their memory allocated. If you cannot control the applications (ie, configure the memory used by the applications) then the only solution is to double or triple the amount of RAM on the machine. HP-UX is a virtual memory machine so with lots of swap, you can run many more processes than will fit into RAM. Of course, everything will run very, very slowly.