HP-UX Reference (11i v2 07/12) - 5 Miscellaneous (vol 9)

n
nproc(5) nproc(5)
(Tunable Kernel Parameters)
NAME
nproc - limits the number of processes allowed to exist simultaneously
VALUES
Failsafe
4200
Default
4200
Allowed values
100 - 30000
This may be set higher, but more will not be used. Setting
nproc below 110 will interfere with the sys-
tems ability to execute in multi-user mode. Some configurations may have a higher minimum.
nkthread must be greater than nproc + 100
.
nproc must be greater than maxuprc + 5
.
Recommended values
1000 processes per processor.
DESCRIPTION
The nproc tunable controls the absolute number of processes allowed on a system at any given time.
Increasing it will allow more processes, and lowering it will restrict the number of processes.
It can be determined that nproc is too low when the proc: table is full message is seen in the
message buffer. The message buffer can be read via
dmesg or syslog
. This message indicates that an
application was unable to create a new process. Setting
nproc too low can cause application failures due
to an inability to fork new processes.
It can be determined how many processes have been used simultaneously by calling
pstat_dynamic
and examining the psd_numprocsallocd
. This field indicates the "high water" mark of the number of
processes that have been simultaneously used.
Who Is Expected to Change This Tunable?
Anyone expecting to run large numbers of processes.
Restrictions on Changing
None. This tunable is dynamic.
When Should the Value of This Tunable Be Raised?
The tunable should be increased when running large numbers of processes simultaneously.
What are the Side Effects of Raising the Value?
None.
When Should the Value of This Tunable Be Lowered?
The value should be lowered only to limit the number of processes on the system, or when there is memory
pressure and the value of
nproc is far above the expected usage.
What are the Side Effects of Lowering the Value?
Increased risk of application failure due to the inability to fork new processes.
What Other Tunable Values Should Be Changed at the Same Time?
Increase nkthread to ensure there are sufficient threads for each process.
nfile and ninode should be increased (and are not by default) to allow applications to manipulate files.
ksi_alloc_max should be adjusted, as the default formula is multiple of nproc.
A single user may not consume all processes on the system (see maxuprc).
Some of these other tunables used to adjust automatically with changes in nproc. These adjustments
must now be made explicitly.
HP-UX 11i Version 2: December 2007 Update − 1 − Hewlett-Packard Company 277