topic Re: PID allocation in Operating System - HP-UX

PID allocation

John Oberlander — Mon, 10 Apr 2006 13:43:59 GMT

Im not finding this question on the forums anywhere so im going to ask. On HP-UX 11iv1 how are pids allocated, how high to they go and when are they reused? Any docs on this would be appreciated.

Thanks,
John

Re: PID allocation

James R. Ferguson — Mon, 10 Apr 2006 13:52:15 GMT

Hi John:

The maxiumum value for a PID (MAXPID) is defined in '/usr/include/sys/param.h'.

Regards!

...JRF...

Re: PID allocation

John Oberlander — Mon, 10 Apr 2006 13:55:32 GMT

Ok thanks! Thats a start, ill take a look at that file. But how do i get to pid's of 20000 when theres never over 5000 or so processess running? At what point to they get recirculated? Does the system use all the pids from 1-MAXPID then recycle through the free ones?

Re: PID allocation

A. Clay Stephenson — Mon, 10 Apr 2006 14:13:27 GMT

Actually the best way is to ask the kernel itself:

echo "effective_maxpid/D" | adb -k /stand/vmunix /dev/kmem

Typically the value is 30,000 --- which has been the UNIX standard for decades although some UNIX flavors go much higher. Once the effective_maxpid is reached, the pid's are recycled starting with the lowest free pid (although a few low values are reserved and thus are skipped over).

Re: PID allocation

John Oberlander — Mon, 10 Apr 2006 14:18:14 GMT

Ah, i knew i never seen pids in the 8M's. My kernel is at 30K also. We're building a process tracking system, im pretty sure this will be enough info.

Thanks much!
John

Re: PID allocation

John Oberlander — Mon, 10 Apr 2006 14:22:38 GMT

Closed