C#: Create CPU Usage at Custom Percentage

Question

I'm looking to test system responsiveness etc. on a few machines under certain CPU usage conditions. Unfortunately I can only create ~100% usage (infinite loop) or not enough CPU usage (I'm using C#).

Is there any way, in rough approximation, as other tasks are running on the system as well, to create CPU usage artificially at 20, 30, 40% (and so forth) steps?

I understand that there are differences between systems, obviously, as CPU's vary. It's more about algorithms/ideas on customizable CPU intensive calculations that create enough usage on a current CPU without maxing it out that I can tweak them then in some way to adjust them to create the desired percentage.

Answer 1

This then?

    DateTime lastSleep = DateTime.Now;            
    while (true)
    {
        TimeSpan span = DateTime.Now - lastSleep;
        if (span.TotalMilliseconds > 700)
        {
            Thread.Sleep(300);
            lastSleep = DateTime.Now;
        }
    }

You could use smaller numbers to get a more steady load....as long as the ratio is whatever you want. This does only use one core though, so you might have to do this in multiple threads.

Answer 2

You could add a threaded timer that wakes up on an interval and does some work. Then tweak the interval and amount of work until you approximate the load you want.

    private void button1_Click(object sender, EventArgs e)
    {
        m_timer = new Timer(DoWork);
        m_timer.Change(TimeSpan.Zero, TimeSpan.FromMilliseconds(10));
    }

    private static void DoWork(object state)
    {
        long j = 0;
        for (int i = 0; i < 2000000; i++)
        {
            j += 1;
        }
        Console.WriteLine(j);
    }

With that and tweaking the value of the loop I was able to add 20%, 60% and full load to my system. It will scale for multiple cores using additional threads for more even load.