Several variables are used to control the number of processes that are available on the system and the number of processes that an individual user can create. The foundation variable is maxusers, which drives the values assigned to max_nprocs and maxuprc.
Originally, maxusers defined the number of logged in users the system could support. Various tables were sized based on this setting when a kernel was generated. Now, the Solaris release does much of its sizing based on the amount of memory on the system, so much of the past use of maxusers has changed. There are still a number of subsystems that are derived from maxusers:
The maximum number of processes on the system
The number of quota structures held in the system
The size of the directory name lookup cache (DNLC)
Signed integer
Lesser of the amount of memory in Mbytes and 2048
1 to 2048, based on physical memory if not set in the /etc/system file.
1 to 4096, if set in the /etc/system file.
Users
No. After computation of dependent variables is done, maxusers is never referenced again.
None
When the default number of user processes derived by the system is too low. This situation is seen by the following message that displays on the system console:
out of processes |
When the default number of processes is too high:
Database servers that have a lot of memory and relatively few running processes, can save system memory by reducing the default value of maxusers.
File servers that have a lot of memory and few running processes can reduce this value, but should explicitly set the size of the DNLC. (See ncsize.)
Compute servers that have a lot of memory and few running processes can reduce this value.
Unstable
For information, see maxusers (Solaris 7 Release).
Specifies number of system process slots to be reserved in the process table for processes with a UID of root (0). For example, fsflush.
Signed integer
5
5 to MAXINT
Processes
No. Not used after the initial parameter computation.
In the Solaris 8 release, any /etc/system setting is honored.
Unstable
Consider increasing to 10 + normal number of UID 0 (root) processes on system. This setting provides some cushion should it be necessary to obtain a root shell during a time when the system is otherwise unable to create user-level processes.
This parameter specifies value of largest possible process ID. Valid for Solaris 8 and later releases.
pidmax sets the value for the maxpid variable. Once maxpid is set, pidmax is ignored. maxpid is used elsewhere in the kernel to determine the maximum process ID and for constraint checking.
Attempts to set maxpid by adding an entry to the /etc/system file have no effect.
Signed integer
30,000
266 to 999,999
Processes
No. Used only at boot time to set the value of pidmax.
Value is compared to that of reserved_procs and 999,999. If less than reserved_procs or greater than 999,999, the value is set to 999,999.
max_nprocs range checking ensures that max_nprocs is always less than or equal to this value.
Changing this parameter is one of the steps necessary to enable support for more than 30,000 processes on a system.
Unstable
Maximum number of processes that can be created on a system. Includes system and user processes. Any value entered in /etc/system is used in the computation of maxuprc.
This value is also used in determining the size of several other system data structures. Other data structures where this variable plays a role are:
Determining the size of the directory name lookup cache (if ncsize is not specified).
Allocating disk quota structures for UFS (if ndquot is not specified).
Verifying that the amount of memory used by configured system V semaphores does not exceed system limits.
Configuring Hardware Address Translation resources for the sun4m and Intel platforms.
Signed integer
10 + (16 x maxusers)
266 to value of maxpid
No
Compared to maxpid and set to maxpid if larger. On Intel platforms an additional check is made against a platform-specific value. max_nprocs is set to the smallest value in the triplet (max_nprocs, maxpid, platform value). Both platforms use 65,534 as the platform value.
Changing this parameter is one of the steps necessary to enable support for more than 30,000 processes on a system.
Unstable
For information, see max_nprocs (Pre-Solaris 8 Releases).
Maximum number of processes that can be created on a system by any one user.
Signed integer
max_nprocs - reserved_procs
1 to max_nprocs - reserved_procs
Processes
No
Compared to max_nprocs - reserved_procs and set to the smaller of the two.
When you want to specify a hard limit for the number of processes a user can create that is less than the default value of however many processes the system can create. Attempting to exceed this limit generates the following warning messages on the console or in the messages file:
out of per-user processes for uid N |
Unstable