Siemens Network Hardware SM2 monitoring system ユーザーズマニュアル
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U3585-J-Z125-8-76
System resource utilization
Notes on SM2 operation
6.1.2
CPU utilization
To facilitate understanding of the factors affecting CPU utilization, readers should be familiar
with the monitoring methods (see section “Acquisition of monitored data” on page 15).
with the monitoring methods (see section “Acquisition of monitored data” on page 15).
Method based on monitoring cycle
At the end of the monitoring cycle, the measured values of the previous monitoring cycle
are calculated for all monitoring programs (with the exception of DISK and TASK). In
contrast to the sample cycle, the monitoring cycle is so much longer that system utilization
by this method based can be disregarded.
are calculated for all monitoring programs (with the exception of DISK and TASK). In
contrast to the sample cycle, the monitoring cycle is so much longer that system utilization
by this method based can be disregarded.
Method based on samples
A monitoring task routine is activated at specific intervals (see the SAMPLING-PERIOD
operand of the MODIFY-MEASUREMENT-PERIODS statement) to take samples.
operand of the MODIFY-MEASUREMENT-PERIODS statement) to take samples.
For each activation of the sampling routine, a basic load has to be processed, regardless
of the variables (devices and tasks) to be monitored.
of the variables (devices and tasks) to be monitored.
In addition to this basic load, further instructions are processed which depend on the
number of objects to be monitored (devices, channels, tasks).
number of objects to be monitored (devices, channels, tasks).
If this number remains constant in the monitoring cycle, CPU utilization is almost directly
proportional to the sampling rate (i.e. halving the sampling cycle, for example, causes the
induced system load to be doubled).
proportional to the sampling rate (i.e. halving the sampling cycle, for example, causes the
induced system load to be doubled).
Lengthening the sampling cycle should be balanced by lengthening the monitoring cycle to
prevent a deterioration in sampling precision.
prevent a deterioration in sampling precision.
The sample-driven method is used for device and channel utilization, the length of queues,
and the monitoring programs CMS and TLM.
and the monitoring programs CMS and TLM.
Method based on events
When this method is used, the monitor is the “passive” component in contrast to the other
system components, which are “active”. When specific events occur in the system (e.g.
starting of an I/O operation), specific monitoring programs are activated which collect the
relevant data (e.g. which device, which task, etc.).
system components, which are “active”. When specific events occur in the system (e.g.
starting of an I/O operation), specific monitoring programs are activated which collect the
relevant data (e.g. which device, which task, etc.).
While the monitor is inactive, no system utilization is induced.
If, however, events occur which are to be monitored, utilization increases in proportion to
the load (i.e. to the number of calls).
the load (i.e. to the number of calls).
When this monitoring method is used, the system load can be reduced only by reducing the
number of objects to be monitored.
number of objects to be monitored.