Siemens U3585-J-Z125-8-76 1 manual Glossary Dilation factor, DMS I/O operations, Dwell time

Glossary

dilation factor

Dilation factors can be determined for individual tasks, for specific task classes and on a system-global basis.

Dwell time

Dilation factor = ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ

Productive RST

Productive RST = productive CPU RST + productive I/O RST

For further information on productive RST, see “time equivalent for the productive performance” on page 458.

A dilation factor smaller than 1 can occur when a task uses asynchronous I/O. In this case, the task uses 2 or more resources simultaneously.

The dilation factor output in SM2R1 report 57 is not comparable with the value "REQUEST DELAY" in the SM2 PCS report and in SM2R1 report 74. This quantity is designed for optimum response time control by PCS.

DMS I/O operations

All accesses to peripheral devices not performed for paging.

dwell time

The time spent by a task in the system comprises the service times of the physical resources and all non-voluntary wait times of the task.

It is not always possible to distinguish between voluntary and non-voluntary wait times without unreasonable outlay.

Example

The BS2000 boursing mechanism can be used to determine both the voluntary wait times (e.g. wait for user input) and the non-voluntary wait times (wait for a busy resource).

For simplicity’s sake, SM2 considers all waits times for boursing, for the PASS and VPASS macros, and for responses to a console message (/PAUSE command or TYPIO macro with response) as voluntary wait times.

SM2 includes the following times in the dwell time:

1.Time spent in the queue for the CPU(s).

This includes the CPU RST and the time spent in Q1.

2.Wait for paging page transfer (time spent in Q3).

3.Wait for execution of DMS I/O operations (time spent in Q4 and Q12 for I/O).

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