nproc.5 (2010 09)

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 - 60000
The system may allow settings higher than 60,000 but such values are unsupported. Setting
nproc
below 110 interferes with the system’s 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 allows more processes, and lowering it restricts the number of processes.
You can determine that
nproc is too low when the proc: table is full
message is seen in the
message buffer. Use
dmesg or syslog to read the message buffer. 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.
You can determine 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?
Increase the value of
nproc 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?
Lower the value 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?
Lowering the value increases the 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.
Adjust
ksi_alloc_max, 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. These adjustments must now be made expli-
citly.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1