以百分比计算 CPU 使用率 UWP 应用程序 Windows 10 IOT

Question

I want to calculate CPU usage in percentage. Currently I am using ProcessDiagnosticInfo to get kernal time and user time. How can I convert this time to percentage or suggest me any other method to find it, if there is any.

private TimeSpan GetTotalCpuTime()
    {
        var totalKernelTime = new TimeSpan();
        var totalUserTime = new TimeSpan();

        var pdis = ProcessDiagnosticInfo.GetForProcesses();
        foreach (var pdi in pdis)
        {
            var cpuUsage = pdi.CpuUsage;
            var report = cpuUsage.GetReport();
            totalKernelTime += report.KernelTime;
            totalUserTime += report.UserTime;
        }

        return totalKernelTime + totalUserTime;
    }

I also know Windows 10 IoT dashboard API " /api/resourcemanager/systemperf ", it return System statistics which include CPU Usage in Percentage but credentials are required to access it, so I don't want to use it.

Answer 1

Each process spends some time in kernel mode and some time in user mode. It is important to note that we do NOT take into account the idle time. Please refer to following code.

    private static readonly Stopwatch Stopwatch = new Stopwatch();
    private static TimeSpan _oldElapsed, _oldKernelTime, _oldUserTime;
    private static int ProcessorCount { get; }
    private static double _carryOver;

    static CpuUsage()
    {
        // Stopwatch will be used to track how much time/usage has elapsed.
        Stopwatch.Start();
        // We'll divide the total used CPU time by the number of processors.
        ProcessorCount = System.Environment.ProcessorCount;
        // Run to store the initial "oldKernel/UserTime" so the first read 
        // isn't super inflated by the application's start-up.
        GetTotalCpuTime();
    }

    /// <summary>
    /// Returns the average percentage of CPU time used since the last time this call was made.
    /// </summary>
    /// <returns></returns>
    private static TimeSpan GetTotalCpuTime()
    {
        // Because we could have more than one process running, add all of them up.
        var totalKernelTime = new TimeSpan();
        var totalUserTime = new TimeSpan();

        // Grab the diagnostic infos for all existing processes.
        var pdis = ProcessDiagnosticInfo.GetForProcesses();
        foreach (var pdi in pdis)
        {
            var cpuUsage = pdi.CpuUsage;
            var report = cpuUsage.GetReport();
            totalKernelTime += report.KernelTime;
            totalUserTime += report.UserTime;
        }

        // Subtract the amount of "Total CPU Time" that was previously calculated.
        var elapsedKernelTime = totalKernelTime - _oldKernelTime;
        var elapsedUserTime = totalUserTime - _oldUserTime;

        // Track the "old" variables.
        _oldKernelTime = totalKernelTime;
        _oldUserTime = totalUserTime;

        // Between both is all of the CPU time that's been consumed by the application.
        return elapsedKernelTime + elapsedUserTime;
    }

    public static double GetPercentage()
    {
        // Because there's a small amount of time between when the "elapsed" is grabbed, 
        // and all of the process KernelTime and UserTimes are tallied, the overall CPU
        // usage will be off by a fraction of a percent, but it's nominal.  Like in the 
        // 0.001% range.
        var elapsed = Stopwatch.Elapsed;
        var elapsedTime = elapsed - _oldElapsed;

        var elapsedCpuTime = GetTotalCpuTime();

        // Divide the result by the amount of time that's elapsed since the last check to 
        // get the percentage of CPU time that has been consumed by this application.
        var ret = elapsedCpuTime / elapsedTime / ProcessorCount * 100;

        // Track the "old" variables.
        _oldElapsed = elapsed;

        // This part is completely optional.  Because the thread could be called between 
        // the time that "elapsed" is grabbed, and the CPU times are calculated, this will
        // cause a "pause" that results in spiking the "CPU usage time" over 100%.  However
        // on the next call, the difference will be "lost" (so if it the CPU percent was
        // at 100% for two calls, but this 'pause' happened, one could report 150% while
        // the next would report 50%.)  By carrying over the values above 100%, we can get
        // a slightly more accurate "average" usage.  
        ret += _carryOver;
        if (ret > 100)
        {
            _carryOver = ret - 100;
            ret = 100;
        }
        else
        {
            _carryOver = 0;
        }

        return ret;
    }

Update: You'll need to declare the appDiagnostics and packageQuery capability in your manifest.

• The appDiagnostics capability allows an app to get diagnostic information.
• The packageQuery device capability allows apps to gather information about other apps.

*.appxmanifest :

  <Capabilities>
    <Capability Name="internetClient" />
    <rescap:Capability Name="appDiagnostics" />
    <rescap:Capability Name="packageQuery" />
  </Capabilities>

Here is a blog about UWP App Diagnostics , hope that is helpful for you. In addition, you can refer to this sample .