Installation guide

shmmni
Number of shared memory identifiers
shmseg
Maximum number of attached shared memory
segments per process
5.6.1.6 Expected Number of Simultaneous Users
The maxusers keyword defines the number of simultaneous users that
your system can support without straining system resources. The number
should not be taken literally; from a performance standpoint, the number
should always be greater than the expected number of real users. This
number also is not the number of logins specified in your system software
license. Refer to the Software Product Description (SPD) for information on
the maximum number of supported users.
The default value assigned to maxusers depends upon the size of your
system. For systems that have 24 MB of memory (small memory systems),
the default value is 16. For all other systems, the default value is 32.
System algorithms use the maxusers keyword to size a number of system
data structures and to determine the amount of space allocated to system
tables. One such table is the system process table, which is used to
determine how many active processes can be running at one time.
Increasing the value of maxusers allocates more system resources for use
by the kernel. However, it also increases the amount of physical memory
consumed by the kernel. Decreasing the value of maxusers reduces kernel
memory usage, but also allocates less system resources. The setting of
maxusers should be a balance between the number of users and the
system hardware configuration (primarily memory size).
Use the following general guidelines to set the value of the maxusers
keyword:
• For systems with limited physical memory and a small number of
users, set maxusers to 8 or 16.
• Setting maxusers to 32 is reasonable for most systems with moderate
hardware configurations and a moderate number of users.
• For larger systems with heavy workloads, set maxusers to 64.
When you modify maxusers, you also modify the value of a number of
other keywords that are based upon maxusers. The keywords that are
based on maxusers are all keywords that control system resources that are
needed by users and should, therefore, be raised or lowered depending
upon the normal user load for your system. The best way to adjust these
keywords is to adjust the maxusers keyword. The following keywords are
based on the maxusers keyword:
5–42 Configuring the Kernel