2.15 Notes about CPU information
This section provides notes about CPU information.
For details about CPU time information, see 4.2.2(1) computerSystem group and 4.3.2(23) computerSystem64 group. For details about CPU usage rate information, see 4.3.2(11) cpuUtil group.
For details about CPU information in HP-UX (IPF), see 4.3.2(16) processor64 group.
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By default, SNMP Agent of HP-UX (IPF) acquires all available information about processors on the OS, regardless of whether a processor is enabled or disabled.
If you set the SNMP_HTC_HPUX_ENABLE_PROCESSOR environment variable to Y in the environment variable definition file SnmpHpunix2, SNMP Agent only acquires information about processors that are enabled. For details about the path of the environment variable definition file, see Appendix A. SNMP Agent Files. The following shows a specification example for the SNMP_HTC_HPUX_ENABLE_PROCESSOR environment variable.
Example
SNMP_HTC_HPUX_ENABLE_PROCESSOR=Y export SNMP_HTC_HPUX_ENABLE_PROCESSOR
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In Solaris, AIX, and Linux, the CPU usage rate information is updated at the CPU usage rate acquisition interval that is set in SNMP Agent (the default is 5 minutes). Therefore, when you collect CPU usage rates, set a collection interval that is greater than the CPU usage rate acquisition interval.
The CPU usage rate acquisition interval (in minutes) is set in the -i option of the htc_monagt1 process, which is a daemon process that regularly collects CPU usage rates. The range for this interval is from 0 to 1,440. If 0 is specified, CPU usage rate information is not collected. In Solaris, AIX, and Linux, during the interval between the start of SNMP Agent and the acquisition of the first CPU usage rate, all the MIB values in the CPU usage rate information are returned as a noSuchName error.
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In Solaris and AIX, CPU information is updated at the CPU time acquisition interval that is set in SNMP Agent (the default is 5 minutes). Therefore, when you collect the CPU time, set a collection interval that is greater than the CPU time acquisition interval.
This CPU time acquisition interval (in minutes) is set in the -s option of the htc_monagt1 process, which is a daemon process that regularly collects CPU time. The range for this interval is from 0 to 1,440. If 0 is specified, CPU time information is not collected. In Solaris and AIX, during the interval between the start of SNMP Agent and the acquisition of the first CPU time information, all the MIB values in the CPU usage rate information are returned as a noSuchName error.
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In Solaris, the online/offline status of the CPU might change. If the status changes, CPU information cannot be obtained from the OS, and as a result, all the MIB values in the CPU usage rate information (except for cpuUtilInterval) are temporarily returned as a noSuchName error.
However, once the CPU time acquisition interval and CPU usage rate acquisition interval pass, making it possible to acquire the CPU information from the OS, all the MIB values can be obtained.
Even when the online/offline status of the CPU changes, the CPU number to be acquired does not change.
Note that the value of CPU time information is reset when the CPU time information acquisition interval passes after the status of the CPU changes.
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In AIX, a CPU might be dynamically added or removed by DLPAR (Dynamic Logical Partition). After a CPU is dynamically added or removed, CPU information cannot be obtained from the OS, and as a result, all the MIB values in the CPU time information and CPU usage rate information (except for cpuUtilInterval) are temporarily returned as a noSuchName error. However, once the CPU time acquisition interval and CPU usage rate acquisition interval pass, making it possible to acquire CPU information from the OS, all the MIB values can be obtained.
Note that the value of CPU time information is reset when the CPU time information acquisition interval passes after a CPU is added or removed.
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In AIX, SNMP Agent acquires the CPU utilization rate, by default, by adding up the CPU utilization rates of individual CPUs, dividing the result by the number of CPUs, and then discarding decimals.
In an SMT environment, you can obtain the CPU utilization rate of the entire machine by specifying Y in the SNMP_HTC_AIX_CPU_SMT environment variable in the SnmpHtcmonagt1 environment variable definition file. For details about the path of the environment variable definition file, see Appendix A. SNMP Agent Files.
The following shows a specification example for the SNMP_HTC_AIX_CPU_SMT environment variable.
Example
SNMP_HTC_AIX_CPU_SMT=Y export SNMP_HTC_AIX_CPU_SMT