Why should I use SpinWait?

问题

I have written two lock-free update helper methods inspired by Joseph Albahari & Marc Gravell

Looking at the 2nd implementation why would I need the SpinWait in the 1st implementation? What are the advantables/disadvantages of one over the other?

Please note this question is not about what SpinWait does but rather specific to how these two methods differ in execution.

public static void LockFreeUpdate1<T>(ref T field, Func<T, T> updater) where T : class
{
    var spinner = new SpinWait();

    T snapshot;    
    while (true)
    {
        snapshot = field;

        if (snapshot.Equals(
               Interlocked.CompareExchange(ref field, updater(snapshot), snapshot))) { return; }

        spinner.SpinOnce();
    }
}


public static void LockFreeUpdate2<T>(ref T field, Func<T, T> updater) where T : class
{
    T snapshot;
    do
    {
        snapshot = field;                

    } while(
        snapshot.Equals(
           Interlocked.CompareExchange(ref field, updater(snapshot), snapshot)));
}

来源：https://stackoverflow.com/questions/31111056/why-should-i-use-spinwait