Configuring kernel parameters

Process limit parameters

General process limit parameters

Parameter Dflt Min Max 64/256/1024 Auto

MAXULWP 200 15 65000

MAXUP 80 30 5000 KVM, Max only

NGROUPS_MAX 16 1 16

NPROC 400 50 12500 KVM, Max only

SHLBMAX 3 2 6

PROCSET_ZOMBIES 0 0 1

Parameter	Dflt	Min	Max 64/256/1024	Auto
MAXULWP	200	15	65000
MAXUP	80	30	5000	KVM, Max only
NGROUPS_MAX	16	1	16
NPROC	400	50	12500	KVM, Max only
SHLBMAX	3	2	6
PROCSET_ZOMBIES	0	0	1

MAXULWP: Maximum number of additional lightweight processes (LWPs) per user created explicitly using _lwp_create. This number does not include the initial LWP that is automatically a part of every process. This limit is not enforced for privileged processes, that is, for those processes with the P_SYSOPS privilege.
MAXUP: Specifies the number of concurrent processes a user without P_SYSOPS privilege can run. The entry can be in the range ``30'' to ``5000'' on xMB machines (where x is 16MB or larger). Traditionally, the maximum has been less than ``100''. This value is per user identification number, not per terminal. If two people are logged in on the same user identification number, the default limit can be reached quickly.
NGROUPS_MAX: Specifies the number of user groups to which a user ID can belong. A user can have multiple ``group'' permissions simultaneously without having to execute the newgrp command -- see getgroups(S-osr5). The kernel restricts this parameter to a range between ``1'' and ``32'', regardless of the tunable parameter setting.
NPROC: An upper bound on the number of processes in the system.
SHLBMAX: Specifies the maximum number of COFF-shared libraries a process can link to. This parameter is primarily of historical interest since COFF-shared libraries are now supported only for backward compatibility.
PROCSET_ZOMBIES: Federal Information Processing Standard (FIPS) 151-2 requires kill applied to a zombie process (or to a set of processes all of which are zombies) to succeed instead of failing with ESRCH. To get this behavior, change the PROCSET_ZOMBIES system tunable from ``0'' (the default value, which produces historical UnixWare behavior) to ``1'', and rebuild the kernel.

Resource limit (rlimit) parameters

Parameter Dflt Min Max

SCORLIM 0x1000000 0 0x7FFFFFFF

HCORLIM 0x1000000 0 0x7FFFFFFF

SCPULIM 0x7FFFFFFF 60 0x7FFFFFFF

HCPULIM 0x7FFFFFFF 60 0x7FFFFFFF

SDATLIM 0x8000000 0x1000000 0x7FFFFFFF

HDATLIM 0x8000000 0x1000000 0x7FFFFFFF

SFNOLIM 64 20 2048

HFNOLIM 2048 20 2048

SFSZLIM 0x3FFFFFFF 0x100000 0x7FFFFFFF

HFSZLIM 0x3FFFFFFF 0x100000 0x7FFFFFFF

SSTKLIM 0x1000000 0x2000 0x7FFFFFFF

HSTKLIM 0x1000000 0x2000 0x7FFFFFFF

SVMMLIM 0x9000000 0x1000000 0x7FFFFFFF

HVMMLIM 0x9000000 0x1000000 0x7FFFFFFF

Parameter	Dflt	Min	Max
SCORLIM	0x1000000	0	0x7FFFFFFF
HCORLIM	0x1000000	0	0x7FFFFFFF
SCPULIM	0x7FFFFFFF	60	0x7FFFFFFF
HCPULIM	0x7FFFFFFF	60	0x7FFFFFFF
SDATLIM	0x8000000	0x1000000	0x7FFFFFFF
HDATLIM	0x8000000	0x1000000	0x7FFFFFFF
SFNOLIM	64	20	2048
HFNOLIM	2048	20	2048
SFSZLIM	0x3FFFFFFF	0x100000	0x7FFFFFFF
HFSZLIM	0x3FFFFFFF	0x100000	0x7FFFFFFF
SSTKLIM	0x1000000	0x2000	0x7FFFFFFF
HSTKLIM	0x1000000	0x2000	0x7FFFFFFF
SVMMLIM	0x9000000	0x1000000	0x7FFFFFFF
HVMMLIM	0x9000000	0x1000000	0x7FFFFFFF

NOTE: The following parameters represent default per process resource limits that are used to populate the rlimit structure. Beginning with Release 4, the ulimit shell command [see sh(C) )] returns to the user several kernel limits obtained from the rlimit structure. In the following parameters the ``S'' prefix indicates soft limits; ``H'', hard limits. Any user process can change its soft limits up to the corresponding hard limit. Only a privileged process can increase hard limits. Setting a parameter to ``0x7FFFFFFF'' indicates it is unlimited.

SCORLIM: The soft limit specifying the largest size, in bytes, of a core file that can be created. A soft limit of ``0'' prevents the creation of core files.
HCORLIM: The maximum value of SCORLIM.
SCPULIM: The soft limit of the maximum combined user and system CPU time, in seconds, that a process is allowed. A SIGXCPU signal will be sent to processes whose CPU time exceeds this value.
HCPULIM: The maximum value of SCPULIM.
SDATLIM: The soft limit specifying the maximum size, in bytes, of a process's heap. If a process attempts to extend its heap beyond this limit using brk(S-osr5), the attempt will fail and errno will be set to ENOMEM.
HDATLIM: The maximum value of SDATLIM.
SFNOLIM: The soft limit specifying the maximum number of open files the process can have. When this limit is exceeded, attempts to open files fail and errno is set to EMFILE.
HFNOLIM: The maximum value of SFNOLIM.
SFSZLIM: The soft limit specifying the largest offset, in bytes, of any single file that can be created by the process. A SIGXFSX signal will be sent to processes that attempt to write a file at an offset greater than this value. In addition, the write will fail with an EFBIG error.
HFSZLIM: The maximum value of SFSZLIM.
SSTKLIM: The soft limit specifying the maximum size, in bytes, of the stack segment for a process. This defines the limit of automatic stack growth by the system. A SIGSEGV signal will be sent to processes that attempt to grow the stack beyond this value. Unless the process has arranged to catch this signal on a separate stack [see sigaltstack(S-osr5) )], this will terminate the process.
The amount of virtual address space reserved for the stack is counted against the process's total address space limit represented by SVMMLIM. Therefore, an increase in SSTKLIM may require a corresponding increase in SVMMLIM.
HSTKLIM: The maximum value of SSTKLIM.
SVMMLIM: The soft limit specifying the maximum address space that can be mapped to a process. Attempts to increase a process's address space beyond this value (that is, with brk(S-osr5), mmap(S-osr5) calls) fail with an ENOMEM error.
A process's address space limit includes the amount of space reserved for its stack, represented by SSTKLIM. Therefore, a decrease in SVMMLIM may require a corresponding decrease in SSTKLIM.
HVMMLIM: The maximum value of SVMMLIM.