Network Hardware User Manual

U3585-J-Z125-8-76 447
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).