Counter classes
Every counter belongs to a counter class. The class determines which filters are available for the counter.
Streamline supports the following basic classes of counters:
- Absolute
Absolute counters report the current, absolute value. Use the
average,maximum, andminimumfilters with absolute counters.- Delta
Delta counters report the number of occurrences since the last measurement. The exact time when the data occurs is unknown, so data is interpolated between timestamps. Use the
accumulateandhertzfilters with delta counters.- Incident
Incident counters are the same as delta counters, except the exact time is known when the data occurs, so no interpolation is calculated.
- Activity
Activity counters report changes in processor activity or state. Use the
averagefilter with activity counters.
The following figure illustrates how the same data that is received from gatord appears differently, depending on the counter class. In each case, the value 10 occurs at the 4.999ms timestamp, and the value 6 occurs at 6.999ms. The red lines show the counter value at 1ms time intervals.
Note
In the delta counter chart, the value of 10 at 4.999ms is amortized from 5ms back to 0ms, because there is no other value, so its value is 2 for that period. The value of 6 at 6.999ms is amortized from 7ms back to 5ms, which is when the last value was received, so its value is 3 for that period.
