Counters

Performance Monitor provides counters that collect, average, and display data about computers running Windows NT. Performance Monitor collects data on various aspects of hardware and software performance, such as use, demand, and available space. You activate a Performance Monitor counter by adding it to a chart or report or by adding an object to a log. Performance Monitor begins collecting data immediately.

In this chapter, counters are associated with an object in the following format:

Object: Counter

For example, the % Processor Time counter of the Process object would appear as Process: % Processor Time to distinguish it from Processor: % Processor Time or Thread: % Processor Time.

Tip

To display the definition for each counter, choose the Explain button in the Add To dialog box. The Explain button works only when you are monitoring current activity, not logs.

There are three types of counters:

• Instantaneous counters display the most recent measurement.

For example, Process: Thread Count displays the number of threads found in the most recent measurement.

• Averaging counters, whose names include per second or percent, measure a value over time and display the average of the last two measurements. When you start these counters, you must wait for the second measurement to be taken before any values are displayed.

For example, Memory: Pages/sec, shows the average number of memory pages found in the last two reads during the second measured.

• Difference counters subtract the last measurement from the previous one and display the difference if it is positive. If it is negative, they display a zero.

Performance Monitor doesn't include any difference counters in its basic set, but they might be included in other applications that use Performance Monitor, and you can write them yourself. For information on writing performance counters, see the Microsoft Windows NT 4.0 Software Developer's Kit.

Performance Monitor includes default counters for each object. For instance, when you open the Add To dialog box, the Processor: % Processor Time counter is selected because this counter is used most often. Each object has a default counter which is highlighted when you select the object. These counters were selected as defaults because they are excellent indicators of the object's activity.

Some hardware and applications designed for Windows NT come with their own counters. Many of these extensible counters are installed automatically with the product, but some are installed separately. In addition, there are a few specialized counters on the compact disc in the Microsoft Windows NT Resource Kit. See your product documentation and Performance Monitor Help for detailed instructions on adding extensible counters.