Enterprise Library Test Guide - Willy .Net

Testing for Performance and Scalability 235
{
int start = Environment.TickCount;
serializer = new XmlSerializer(typeof(OrderedItem),"ns");
int stop = Environment.TickCount;
Console.WriteLine(" Time create serializer: {0}
milliseconds", stop - start);
}
}
}
If you examine the Visual Studio Team System profiler, you see that although the
code creates the XmlSerializer object 11 times, the program incurs the largest costs
when it first compiles the types inside the XmlSerializer object. After this, subsequent
calls use the compiled version in the cache. Table 28 lists the information from
the profiler.
Table 28: Profiler Information
Method name
Time in ms
Number of
calls
System.Xml.Serialization.XmlSerializer..ctor 795.67 11
System.Xml.Serialization.XmlSerializer.GenerateTempAssembly 645.37 1
System.Xml.Serialization.TempAssembly..ctor 644.42 1
System.Xml.Serialization.TempAssembly.GenerateAssembly 414.6 1
System.Xml.Serialization.Compiler.Compile 281.72 1
Extrapolating Workload Profiles
It is possible to extrapolate workload characterizations for the load tests, even though
you do not know the actual application that will host the application blocks or the
systems on which the application will run.
Defining a load test is one of the steps in writing a performance test plan specification.
The load test runs concurrent scenarios and records a system’s behavior. You
generate a test load by creating virtual users and a simulation that accurately reflects
how actual users use the application.
To characterize a performance test workload, you should associate the number of
concurrent users with the think times that occur between iterations.
When you create a load test for an application, you often have no data about how
many concurrent users there actually will be or the type of computer or network you
need to consider. For example, your load test may be for an application that will actually
run on a single computer with a processor and a disk subsystem or it may run
over an intranet. However, you can use Little’s Law to extrapolate from a given performance
specification or goal and calculate a realistic number of concurrent users.