Siemens SM2 monitoring system manual Glossary Time equivalent for the productive performance

Glossary

time equivalent for the productive performance

In determining the RST (resources service time), a distinction is made between the CPU and the peripheral devices as follows:

1.For the CPU the RST is the time in which instructions are processed in the TU and TPR states. This time is called productive CPU RST (the SIH share of the productive performance is not counted; see above).

2.For the peripheral equipment, the RST is the firmware service time of the devices for performing an I/O operation.

The firmware duration is defined as the time from I/O initiation (START-DEVICE or START-SUBCHANNEL instruction) to I/O termination (channel interrupt). Only I/O operations initiated by DMS are counted. This share is called productive I/O RST.

In practical operation, the firmware duration is affected by other tasks in the system. The positioning time during disk access, for example, depends on prior events, i.e. the current arm position, and on operating system strategies. In BS2000, arm movement optimization is used, i.e. the operating system tries to start I/O accesses in such a way that arm movements are minimized.

By adding the waiting time of an I/O request in the device queue of the system to the firmware duration, the software service time (also called software duration) is obtained.

transaction

Total number of system responses to a user request.

(Please refer to the normal usage in the UTM manuals for the meaning of the term "transaction" in the UTM reports).

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