C# Test running configuration(*.runsettings)

By default Visual studio will run tests in 1 thread. I want to run it in parallel. I have *.runsettings file with code below:

  <?xml version="1.0" encoding="utf-8"?>
    <RunSettings>
      <RunConfiguration>
        <MaxCpuCount>4</MaxCpuCount>
      </RunConfiguration>
    </RunSettings>

When I rebuild solution or run the tests I'm getting the error below in OUTPUT window:

Invalid settings 'RunConfiguration'. Unexpected XmlElement: 'MaxCpuCount'.

I copy pasted the code for *.runsettings from MSDN doc.

I'm using Visual studio 2015.

Thanks for your help.