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Python Programming On Win32 by Mark Hammond, Andy Robinson

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Anatomy of the Performance Monitor

To use the Performance Monitor, an application must register one or more Performance Monitor objects. An object is a logical grouping of Performance Monitor data; it is quite common for an application to have a single object, grouping all performance-related data from the application in this single object.

For each object, the application must register one or more counters . A counter provides a single piece of performance data. Attributes about a counter include the units and the default scale for the final value. The units indicate how the counter values are to be transformed (for example, turned into a rate per second), while the scale defines a multiplication factor applied before the value is displayed or graphed.

For example, let’s assume the application needs to keep a counter for connections per second made to it. The application is fast, so expect a hit rate in the thousands of connections per second. You would define your counter as having units of “per second” and a scale of “divide by 100.” All the application needs to do is increment the counter once for each connection established, and the Performance Monitor itself will handle the transformation of the raw counter data to a value in the range 1 to 100 that represents the connections per second. The Performance Monitor has kept track of how many counter increments were made in the last second and applied the appropriate conversions.

As you can see, from the application’s point of view ...

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