The performance analysis reports express most quantified data as percentages. In most cases, absolute values (for example, actual number of observations in which execution was in DB2® services) would not, by themselves, be particularly meaningful. This is because the total number of samples chosen for an observation session is somewhat arbitrary. The percentage of activity attributed to a system object, on the other hand, provides a much better measure of the impact of that system object on performance. Furthermore, when expressed as percentages, quantification is likely to remain roughly equal if the sampling frequency and duration parameters are varied.
In order to effectively interpret the performance analysis reports it is important that you understand how these percentages are computed. The formulae vary depending upon what type of system activity is reported.
Note that observations of CPU Waiting and CPU Unavailable are excluded from the calculation. The objective is to report the relative demand placed on CPU resources by system objects.
I/O activity concurrent CPU execution is observed.
Concurrent I/O activity is observed for multiple devices.
Concurrent CPU execution is observed. This is only possible on a system with multiple CPUs (a multiprocessor).
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