process_id_min(5)process_id_min(5)NAMEprocess_id_min - specify a minimum value for process IDs (PIDs)
VALUES
Failsafe
Default
Minimum
Maximum
must be less than or equal to If the difference between and inclusive
is less than is effectively limited to this difference.
DESCRIPTION
The tunable specifies the minimum process ID (PID) value to generate
for new processes. It allows application developers to duplicate an
environment where PID values are large for the purpose of software val‐
idation.
This tunable is primarily intended for development environments.
Who is Expected to Change This Tunable?
Anyone interested in software program validation in an environment
where PIDs have large values.
Restrictions on Changing
Changes to the tunable are effective immediately. However, any exist‐
ing processes and their PIDs are not changed.
It is recommended that the system be rebooted after specifying this
tunable so that all PIDs in the system will have values in the selected
range.
When Should the Value of This Tunable Be Raised?
Raise this tunable to validate software for tolerance of large PID val‐
ues in a development environment.
What Are the Side Effects of Raising the Value?
If the difference between and is less than the number of processes
allowed to exist simultaneously will be lower than the value of
When Should the Value of This Tunable Be Lowered?
Lower this tunable when the system is meant to be moved from a develop‐
ment to a production environment.
What Are the Side Effects of Lowering the Value?
If the difference between and is less than the number of processes
allowed to exist simultaneously will be lower than the value of
What Other Tunable Values Should Be Changed at the Same Time?
It may be desirable to change The tunable should, ideally, be set for
the maximum value when validating software which uses PIDs. When
changing it is recommended that the system be rebooted to ensure all
processes have PIDs within the desired range.
WARNINGS
All HP-UX kernel tunable parameters are release specific. This parame‐
ter may be removed or have its meaning changed in future releases of
HP-UX.
The HP-UX kernel may silently round the selected values for and/or (for
example, to the nearest power of 2) in order to accommodate the PID
generation algorithm.
It is recommended that validation of software be carried out with the
largest configurable value (1,073,741,567) for the tunable, in conjunc‐
tion with the tunable set to something of the same magnitude (for exam‐
ple, 1,000,000,000).
The manpage for (see process_id_max(5)) should be consulted for infor‐
mation about potential application issues with large PID values.
Because session IDs (SIDs) and process group IDs (PGIDs) are the same
as the process ID of the session or group leader, an increase in the
minimum PID also increases the minimum SID and PGID.
The system may assign process ID values less than to certain special
system processes.
Booting the system with set to a non-zero value may cause the initial‐
ization process (aka init) to have a PID of something other than 1.
However, most system utilities and commands will, by default, report
the value of the initialization process's PID as 1. For example,
returns 1 if the caller's parent is the initialization process, regard‐
less of its actual PID.
Installation of optional kernel software, from HP or other vendors, may
cause changes to tunable parameter values. After installation, some
tunable parameters may no longer be at the default or recommended val‐
ues. For information about the effects of installation on tunable val‐
ues, consult the documentation for the kernel software being installed.
For information about optional kernel software that was factory
installed on your system, see at
AUTHOR
was developed by HP.
SEE ALSOinit(1M), fork(2), getppid(2), nproc(5), process_id_max(5).
whitepaper, available on
Tunable Kernel Parameters process_id_min(5)