Siemens U3585-J-Z125-8-76 1 manual UTM monitoring program, Write task and I/O buffer

Notes on SM2 operation System resource utilization

The event-driven method is used by the monitoring programs CHANNEL-IO, DISK, DISK-

FILE, ISAM, NET-DEVICE, PERIODIC-TASK, RESPONSETIME, SERVICETIME, SYSSTAT and TASK, as well as for user task statistics.

UTM monitoring program

If UTM applications are running on the system and these applications provide data for SM2, the following additional load occurs in each UTM task: an additional 500 instructions (approx.) are required at the end of each dialog step and each asynchronous conversation in order to provide this data. For a typical application, this amounts to considerably less than 1% of the entire processing volume.

The resulting additional load on the system thus depends on the throughput in the applica- tions, but can generally be ignored.

If values are also provided from the database systems, an additional load arises in these database systems in order to capture the monitored data. This load depends on the database system itself and the version used. For this reason, no general rule can be given.

Write task and I/O buffer

SM2 creates a write task (system task with TSN=SM2W) for writing to the SM2 output file. This task exists only from OPEN to CLOSE and is activated only when an I/O buffer is full. The input/output operation is controlled by the write task, and the CPU is required for task execution (CPU time for TPR and SIH states). The CPU time required for writing to the I/O buffer is assigned not to the write task but to the initiating task (system task or SIH processor state).

The data rate for writing to the I/O buffer depends on whether the record is written

–by the monitoring task at the end of a monitoring cycle,

–by another task, or

–in the SIH processor state

In the first case, the data rate depends on the number of active monitoring programs (data records) and monitored objects, as well as the duration of the monitoring cycle (OFFLINE- PERIOD operand in the MODIFY-MEASUREMENT-PERIODS statement). If the same data records remain active during monitoring, the workload is inversely proportional to the duration of the monitoring cycle. The second and third cases only apply to the monitoring programs TASK and DISK.

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