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Setting Boot Time Values for Shared Memory and Semaphore Parameters
When setting shared memory and semaphore parameters, if the boot time value is less than the recommended number, you must increase it. To evaluate whether you need to increase the value of a parameter's boot time value, use the guidelines in the following table.
Settings for the /etc/system File
For Parameter... | Which is... | Do This... | Example |
|---|---|---|---|
IPC Semaphores | |||
semsys: seminfo_semmns | Number of semaphore identifiers, system-wide | Add (50 + 50 multiplied by the number of instances) to the current value | If the current value on the computer is 100 and you have one system collector and one Oracle® collector running on the computer, set the value to 250. |
semsys: seminfo_semmap | Number of entries in the semaphore map | Set equal to semsys:seminfo_semmni + two | If semsys: seminfo_semmni was set to 256, set semsys: seminfo_semmap equal to 258. |
semsys: seminfo_semmni | Number of semaphore identifiers (semaphore sets), system-wide | Add (25 + 25 multiplied by the number of instances) to the current value | If the current value of the comput is 100 and you will be running one system collector, set the value to 150. |
semsys: seminfo_semmnu | Maximum number of undo structures, system-wide | No specific recommendation. PATROL Perform does not use undo structures | As a general rule, you can set seminfo_semmnu equal to seminfo_semmni to provide for an undo structure for each semaphore. This semaphore is obsolete in Solaris 10 and later. |
semsys: seminfo_semmsl | The maximum number of semaphores per unique identifier | No specific recommendation. PATROL Perform will attach two semaphores per identifier. | semsys:seminfo_semmsl should remain at its current value. |
semsys: seminfo_semopm seminfo_semume seminfo_semvmx seminfo_semaem |
| No specific recommendations for any of these semaphore settings. They have no impact on the operation of PATROL Perform. | seminfo_semume, seminfo_semvmx, and seminfo_semaem are obsolete in Solaris 10 and later. |
IPC Shared Memory | |||
shmsys: shminfo_shmm | The maximum size of a shared memory segment. | No specific recommendation. The default value is high enough for PATROL Perform. | PATROL Perform allocates small segments, so this value will never be a limiting factor. |
shmsys: shminfo_shmmin | Minimum size of an IPC shared memory segment that can be created | The system default of 1 is recommended. | shmsys:shminfo_shmmin should always be set to 1. |
shmsys: shminfo_shmmni | System wide limit on the number of shared memory segments | Add (25 + 25 multiplied by the number of instances) to the current value | If the current value of the computer is 100 and you will be running one system collector, set the value to 150. |
shmsys: shminfo_shmseg | Limit on the number of shared memory segments that one process can create | Add (25 + 25 multiplied by the number of instances) to the current value | If the current value of the computer is 100 and you will be running one system collector, set the value to 150. |
On Solaris 7 and Later Systems
Issue the /etc/sysdef -i command to view the current settings. See man pages for more information about the sysdef command. For Solaris,you also need to review the settings for the sem-mns and sem-map parameters.
For sem-mns (maximum number of semaphores available on the system, default value =60), increase the value by 140.
For sem-map (maximum number of entries in the semaphore map, default value=10), increase the value by 90.
On Linux Systems
The shared memory and semaphore requirements on Linux are the same as the requirements for other UNIX variants.
If there are not other shared memory intensive applications running on the Linux computer (such as Oracle) it will not typically be necessary to change the default IPC kernel settings under Linux. The current shared memory settings on the computer can be seen by running the following command:
ipcs -l
Shared memory and semaphore settings can be changed in the Linux kernel by editing the kernel settings files in /proc/sys/kernel. The files are: sem, shmall, shmmax, shmmni. The shm* files contain a single value that equates to the setting on the computer. The sem file has four values separated by tabs. Updating these files changes the specified setting in the running kernel. However, the default kernel limits are sufficient to run Perform on the computer.
On Hewlett-Packard Systems
On HP-UX you can use the SAM tool to change the settings for resource limits and to reconfigure the kernel. SAM will relink the kernel. See the man pages for more information about using SAM for this purpose. Use the recommended values shown in the following table to adjust the settings for HP-UX.
On IBM AIX Systems
This does not apply to AIX, because the system dynamically manages resource limits.