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Hey guys, I am here again with a problem.
In my program I need to calculate the current CPU usage.

I have searched google and found similar code across multiple websites but it just feels way too complicated for what I need to do AND my CPU never hits 100% usage with this calculation.

Not only does it look too complicated but i do not even understand the code, and when i write a program if i use code i find from google i try to understand it to become a better programmer.

So here is the code i found, if you know a better solution please help me out, and possibly try to explain it, and if there is not a better solution please help me understand this code.

Thank you all!

C#
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Threading;
using System.Diagnostics;
using ComTypes = System.Runtime.InteropServices.ComTypes;
namespace CPU_PI_Crusher
{
    public class CpuUsage
    {
        //Imports the needed DLL
        [DllImport("kernel32.dll", SetLastError = true)]
        //get needed system file time types
        static extern bool GetSystemTimes(
                    out ComTypes.FILETIME lpIdleTime,
                    out ComTypes.FILETIME lpKernelTime,
                    out ComTypes.FILETIME lpUserTime
                    );
        //Com system information vars
        ComTypes.FILETIME prevSysKernel;
        ComTypes.FILETIME prevSysUser;
        //Time span needed later on
        TimeSpan prevProcTotal;
        //time of last run
        DateTime lastRun;
        //integer object
        Int16 int16CpuUsage;
        
        //Run Count
        long longRunCount;
        /// <summary>
        /// Initilize and define all the variables above
        /// </summary>
        public CpuUsage()
        {
            int16CpuUsage = -1;
            lastRun = DateTime.MinValue;
            prevSysUser.dwHighDateTime = prevSysUser.dwLowDateTime = 0;
            prevSysKernel.dwHighDateTime = prevSysKernel.dwLowDateTime = 0;
            prevProcTotal = TimeSpan.MinValue;
            longRunCount = 0;
        }
        /// <summary>
        /// Gets the CPU Usage and return a short
        /// </summary>
        /// <returns></returns>
        public short GetUsage()
        {
            short cpuCopy = int16CpuUsage;
            if (Interlocked.Increment(ref longRunCount) == 1)
            {
                //Detect if enough time has passed
                if (!EnoughTimePassed)
                {
                    //Decrease run count
                    Interlocked.Decrement(ref longRunCount);
                    return cpuCopy;
                }
                //Define system variables
                ComTypes.FILETIME sysIdle, sysKernel, sysUser;
                TimeSpan procTime;
                //Get current process
                Process process = Process.GetCurrentProcess();
                //Timespan is the CPU time
                procTime = process.TotalProcessorTime;
                //Get the system times of the system variables
                if (!GetSystemTimes(out sysIdle, out sysKernel, out sysUser))
                {
                    Interlocked.Decrement(ref longRunCount); //decrease run count
                    return cpuCopy;
                }
                //If not the first run
                if (!IsFirstRun)
                {
                    UInt64 sysKernelDiff = SubtractTimes(sysKernel, prevSysKernel); //Gets time difference
                    UInt64 sysUserDiff = SubtractTimes(sysUser, prevSysUser); //Gets time difference
                    UInt64 sysTotal = sysKernelDiff + sysUserDiff; //total time
                    Int64 procTotal = procTime.Ticks - prevProcTotal.Ticks; //Total CPU ticks
                    //Usage greate than 0
                    if (sysTotal > 0)
                    {
                        int16CpuUsage = (short)((100.0 * procTotal) / sysTotal); //calculate usage
                    }
                }
                //Define system variables
                prevProcTotal = procTime;
                prevSysKernel = sysKernel;
                prevSysUser = sysUser;
                lastRun = DateTime.Now; //Get the current time
                cpuCopy = int16CpuUsage;
            }
            //decrease the current run time
            Interlocked.Decrement(ref longRunCount);
            //return  cpu usage
            return cpuCopy;
        }
        /// <summary>
        /// Subtract from two com type file times
        /// </summary>
        private UInt64 SubtractTimes(ComTypes.FILETIME a, ComTypes.FILETIME b)
        {
            UInt64 aInt = ((UInt64)(a.dwHighDateTime << 32)) | (UInt64)a.dwLowDateTime;
            UInt64 bInt = ((UInt64)(b.dwHighDateTime << 32)) | (UInt64)b.dwLowDateTime;
            return aInt - bInt;
        }
        /// <summary>
        /// Detect if enough time is passed
        /// </summary>
        private bool EnoughTimePassed
        {
            get
            {
                const int minimumElapsedMS = 250; //Predefined time elspase
                TimeSpan sinceLast = DateTime.Now - lastRun; //Gets the timspan between two datetimes
                return sinceLast.TotalMilliseconds > minimumElapsedMS; //calculate time from the timespan
            }
        }
        /// <summary>
        /// Getter for the FirstRun Object
        /// </summary>
        private bool IsFirstRun
        {
            get
            {
                return (lastRun == DateTime.MinValue);
            }
        }
    }
}
Posted
Updated 18-Jun-11 12:15pm
v2
Comments
Sergey Alexandrovich Kryukov 18-Jun-11 18:19pm    
Isn't it better to provide a Web link instead of the copy of the work? You did not even give a credit to the author...
--SA

1 solution

Have a look at this link.[^]
 
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Comments
thexcodec 19-Jun-11 22:28pm    
Sure that links works mate?
"Oops! Google Chrome could not connect to zamov.online.fr"
Dr.Walt Fair, PE 19-Jun-11 22:31pm    
The link works for me in Firefox.
thexcodec 20-Jun-11 12:42pm    
ya it works now. Server prob was down for a second or too. The code in the example you gave me looks a lot smaller and i understand it! ill test it and see if it works.

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