How to calculate Vusers for a TruClient test

  1. Run a Controller scenario with one virtual user.
  2. Go to the target LoadGenerator machine. If it’s a remote LoadGenerator, use a remote desktop session.
  3. Open Windows Performance Monitor. (Open the Windows search bar and look for perfmon.exe or open the Control Panel and go to “System and Security -> Administrative Tools – Performance Monitor”).
  4. Click on Performance Monitor in order to add a new counter as shown in the below image.

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  1. Add a counter for Processor Time and Working Set by process (the Web Browser that is being used by the virtual user)

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Working Set is the current size, in bytes, of the Working Set of this process. The Working Set is the set of memory pages touched recently by the threads in the process.

CPU time (or process time) is the amount of time for which a central processing unit (CPU) was used for processing instructions of a computer program or operating system. In other words, CPU utilization.

Now you are monitoring the CPU usage with one Vuser. With this information you can estimate how many Vusers you can run in this LoadGenerator.

  • Let’s say we want to keep our CPU usage under 70%. We need to monitor the average CPU usage during the test with one Vuser.
  • In this example, we see an average of 12 percent average usage. If we divide 70 / 12 that gives us 5.8. That means that we can run approximately 5 or 6 Vusers in this LG.

After completing the steps above, you will have an estimate of Vusers you will be able to run in your machine, and can estimate how many LoadGenerators you need for your test.

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