About Counter Sets

When you create a load test, Visual Studio Team System Test Edition lets you specify a counter set. A counter set is set of performance counters that are useful to monitor during a load test run. Counter sets are part of the load test and apply to all the scenarios in it. They are organized by technology, for example, ASP.NET or SQL counter sets.

Counter sets are gathered on computers that you specify. The association between a counter set and a computer that is used during a load test is a counter set map. For example, the Web server you are testing might have ASP.NET, IIS, and .NET application counter set mappings.

By default, performance counters are collected on the controller and agents. For more information, see Controllers, Agents, and Rigs.

It is important that you add the servers under test to the list of computers on which to collect counters. That way, any important system data is collected and monitored during the load test.

The load test tools collect and graph performance data using counters over time. Counter data is collected at user-specified intervals during a load test run. You can view the counters at run time or you can view them after a load test run. At run time, you use the Load Test Monitor and after a run you use the Load Test Analyzer. For more information, see Analyzing Load Test Runs.

Counter data is gathered on the server and on any computer where a test is run. If you have set up a set of agent computers on which to run your tests, counters are gathered on those computers as well.

There are three counter categories: percentages, counts, and averages. Some examples are % CPU usage, SQL Server lock counts, and IIS requests per second.

Performance data for individual HTTP requests is reported by the computer that runs a test such as an agent computer. For requests, you might monitor data such as Average Time to First Byte, Response Time, and Requests per Second.

To ease collection of performance data on a Web server, Test Edition also provides predefined, named counter sets, based on technology for use in load tests. These sets are useful when you are analyzing a server running IIS, ASP.NET, or SQL Server. Counters not provided in the default set of counter can be added by using the Load Test Editor. It is important that you add the computers or servers under test to your load test to make sure that that you can monitor resource use on these computers. For more information, see How to: Manage Counter Sets.

Results analysis of load runs frequently requires domain-specific knowledge of a particular area in order to know what data to gather, where to set threshold rules, and how to tell when a measurement reflects a specific problem in the application. For more information, see About Threshold Rules.

When you create a load test with the Load Test Wizard, you add an initial set of counters. For more information, see How to: Specify Counter Sets.

After you create your load test, you can edit the Counter Set in the Load Test Editor. For more information, see Load Test Counter Sets.

During a load test run, the performance counter data is collected and stored in the Load Test Results Store. For more information, see About the Load Test Results Repository.

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