public void TestInstructionCounting()
{
int externalValue = 0;
PerformanceMetrics Benchmark(int iterations)
{
using var counter = new PerfCounter();
counter.Start();
for (int i = 0; i < iterations; i++)
{
externalValue += (int)Math.Sqrt(2);
}
counter.Stop();
return(counter.GetResults());
}
for (int i = 0; i < 3; i++)
{
var measurement = Benchmark(1000);
}
int baseIterations = 1;
var overhead = Benchmark(baseIterations);
Console.WriteLine($"Overhead: {overhead.Instructions}");
int iterations = 1024;
var finalMeasurement = Benchmark(iterations + baseIterations);
Console.WriteLine($"Final: {finalMeasurement.Instructions}");
var cleaned = finalMeasurement - overhead;
Console.WriteLine("Per iteration:");
Console.WriteLine($"Instructions: {cleaned.Instructions / (double)iterations:0.00}");
Console.WriteLine($"Cycles: {cleaned.Cycles / (double)iterations:0.00}");
Console.WriteLine($"Task clock: {cleaned.TaskClock / (double)iterations:0.00}");
Assert.That(overhead.Instructions, Is.GreaterThan(0));
Assert.That(finalMeasurement.Instructions, Is.GreaterThan(overhead.Instructions));
Assert.That(cleaned.Instructions, Is.GreaterThan(iterations / 32));
// uncomment the following line to see the results
Assert.Fail();
}
