What is a "non-system" process?

 
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jjrrww
New Member

What is a "non-system" process?

global_pstat_body.h has the following comment in struct __pst_dynamic referring to "non-system processes"

What *IS* a system process (from HP/UX' perspective)?

What distinguishes a system process from a non-system process?

What attribute can I examine to know the difference? Speculation: processes with PPID = 0?

- John

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struct __pst_dynamic {
... lines omitted
* The following 8 elements are sums across all non-system
* processes. Thus, "total virtual memory" refers to the number of
* virtual pages used by all non-system processes. The word
* "active" means that a thread in a process has run in the last 20
* seconds. Thus, "active virtual memory" refers to the sum of the
* virtual memory of all processes which have had a thread run in the
* last 20 seconds. "Real memory" refers to pages residing in core.
* Shared memory is included in all these totals, but is counted only
* once. Fields that end in "txt" apply to text pages only.
*/
_T_LONG_T psd_vm; /* total virtual memory */
_T_LONG_T psd_avm; /* active virtual memory */
_T_LONG_T psd_rm; /* total real memory */
_T_LONG_T psd_arm; /* active real memory */
_T_LONG_T psd_vmtxt; /* virt mem text */
_T_LONG_T psd_avmtxt; /* active virt mem text */
_T_LONG_T psd_rmtxt; /* real mem text */
_T_LONG_T psd_armtxt; /* active real mem text */
2 REPLIES 2
Don Morris_1
Honored Contributor
Solution

Re: What is a "non-system" process?

A process created by and for the maintenance of the system (kernel daemons are the best example). A user process is a normal application started by a user login instead of the system itself.

Distinguished by having PS_SYS in the pst_flag field in the pst_status structure returned by pstat_getproc(). [The PPID may be non-zero if a kernel daemon starts another kernel daemon process].
jjrrww
New Member

Re: What is a "non-system" process?

Perfect.

Can I therefore infer that all processes have swapper (PID 0) at the top of the process tree, but only those with init (PID 1) in the tree are user/non-system processes?

(Just getting my head around the process and scheduling concepts)