c# 获取某个进程的CPU使用百分百（类似任务管理器中显示CPU）

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Management;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace 进程监控
{
    class Program
    {
        static void Main(string[] args)
        {
            Process[] processes = Process.GetProcessesByName("taskmgr");
           
            foreach (Process instance in processes)
            {
                Console.WriteLine("");
                Console.WriteLine("ProcessName:" + instance.ProcessName);
                try
                {
                    //Console.WriteLine("提交大小\t" + instance.PagedMemorySize64 / 1024);
                    Console.WriteLine("工作设置(内存)\t" + instance.WorkingSet64 / 1024);
                    Console.WriteLine("线程数\t" + instance.Threads.Count);
                    Console.WriteLine("句柄数\t" + instance.HandleCount);

                }
                catch { }
            }

            Process p = processes[1];
            //PerformanceCounter ramCounter = new PerformanceCounter("Process", "Working Set", p.ProcessName);
            //PerformanceCounter cpuCounter = new PerformanceCounter("Process", "% Processor Time", p.ProcessName);

            var objQuery = new ObjectQuery("select * from Win32_Process WHERE ProcessID = " + p.Id);
            var moSearcher = new ManagementObjectSearcher(objQuery);
            DateTime firstSample = DateTime.MinValue, secondSample = DateTime.MinValue;

            double ProcessorUsage;
            double msPassed;
            ulong u_OldCPU = 0;
            while (true)
            {
                var gets = moSearcher.Get();
                foreach (ManagementObject mObj in gets)
                {
                    try
                    {
                        if (firstSample == DateTime.MinValue)
                        {
                            firstSample = DateTime.Now;
                            mObj.Get();
                            u_OldCPU = (ulong)mObj["UserModeTime"] + (ulong)mObj["KernelModeTime"];
                        }
                        else
                        {
                            secondSample = DateTime.Now;
                            mObj.Get();
                            ulong u_newCPU = (ulong)mObj["UserModeTime"] + (ulong)mObj["KernelModeTime"];