Rdtsc performance test

using System;
using System.Diagnostics;
using System.Threading;

namespace nettest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine($"Rdtsc ticksPerMillisecond: {ticksPerMillisecond}");

            MethodA_UtcNow();
            MethodB_RdtscP();
            MethodC_Rdtsc();
            MethodD_StopwatchGetTimestamp();
            MethodE_EnvironmentTickCount();
            MethodX_SimpleCount();
        }

        private static void MethodA_UtcNow()
        {
            long cnt = 0;
            var doneTime = DateTime.UtcNow.AddSeconds(1).Ticks;
            var startDT = DateTime.Now;
            while (DateTime.UtcNow.Ticks <= doneTime)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("UtcNow      Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        private static void MethodE_EnvironmentTickCount()
        {
            long cnt = 0;
            int doneTick = Environment.TickCount + 1000;
            var startDT = DateTime.Now;
            while (Environment.TickCount <= doneTick)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("TickCount   Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        static ulong ticksPerMillisecond = CalibrateTSCTicksPerMillisecond();

        private static ulong CalibrateTSCTicksPerMillisecond()
        {
            ulong rate = 0;
            ulong n = 100;
            for (ulong i = 0; i < n; i++)
            {
                ulong res = CountTSCTicksPerMillisecond();
                if (i == 0 || res < rate)
                    rate = res;
            }
            return rate;
        }

        private static ulong CountTSCTicksPerMillisecond()
        {
            ulong tsc1 = Rdtsc.TimestampP();
            long ticks2 = DateTime.UtcNow.Ticks + TimeSpan.TicksPerMillisecond;
            while (DateTime.UtcNow.Ticks < ticks2) ;
            ulong tsc2 = Rdtsc.TimestampP();
            return tsc2 - tsc1;
        }

        private static void MethodC_Rdtsc()
        {
            long cnt = 0;
            ulong doneTick = Rdtsc.Timestamp() + ticksPerMillisecond * 1000;
            var startDT = DateTime.Now;
            while (Rdtsc.Timestamp() <= doneTick)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("Rdtsc       Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        private static void MethodB_RdtscP()
        {
            long cnt = 0;
            ulong doneTick = Rdtsc.TimestampP() + ticksPerMillisecond * 1000;
            var startDT = DateTime.Now;
            while (Rdtsc.TimestampP() <= doneTick)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("RdtscP      Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        private static void MethodD_StopwatchGetTimestamp()
        {
            long cnt = 0;
            long doneTick = Stopwatch.GetTimestamp() + TimeSpan.TicksPerMillisecond * 1000;
            var startDT = DateTime.Now;
            while (Stopwatch.GetTimestamp() <= doneTick)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("Stopwatch   Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        private static void MethodX_SimpleCount()
        {
            readyEvent.Reset();
            Thread counter = new Thread(CountBool);
            Thread waiter = new Thread(WaitBool);
            counter.Start();
            waiter.Start();
            waiter.Join();
            counter.Join();
        }

        private static void CountBool()
        {
            long cnt = 0;
            readyEvent.WaitOne();
            var startDT = DateTime.Now;
            while (!done)
            {
                cnt++;
            }
            var endDT = DateTime.Now;
            Console.WriteLine("SimpleCount Time Taken: {0,30} Total Counted: {1,20}", endDT.Subtract(startDT), cnt);
        }

        private static volatile bool done = false;
        private static ManualResetEvent readyEvent = new ManualResetEvent(false);

        private static void WaitBool()
        {
            readyEvent.Set();
            Thread.Sleep(TimeSpan.FromSeconds(1));
            done = true;
        }

    }
}