Display multiple cores performance in WPF

Question

I want to use Dynamic Data Display library to display the CPU performance with WPF.

Here is the code.

using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Media;
using System.Windows.Threading;
using Microsoft.Research.DynamicDataDisplay;
using Microsoft.Research.DynamicDataDisplay.DataSources;

namespace WpfPerformance
{
    public partial class MainWindow : Window
    {
        private ObservableDataSource<Point> dataSource = new ObservableDataSource<Point>();
        private PerformanceCounter cpuPerformance = new PerformanceCounter();
        private DispatcherTimer timer = new DispatcherTimer();
        private int i = 0;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void AnimatedPlot(object sender, EventArgs e)
        {
            cpuPerformance.CategoryName = "Processor";
            cpuPerformance.CounterName = "% Processor Time";
            cpuPerformance.InstanceName = "_Total";

            double x = i;
            double y = cpuPerformance.NextValue();

            Point point = new Point(x, y);
            dataSource.AppendAsync(base.Dispatcher, point);

            cpuUsageText.Text = String.Format("{0:0}%", y);
            i++;
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            plotter.AddLineGraph(dataSource, Colors.Green, 2, "Percentage");
            timer.Interval = TimeSpan.FromSeconds(1);
            timer.Tick += new EventHandler(AnimatedPlot);
            timer.IsEnabled = true;
            plotter.Viewport.FitToView();
        }
    }
}

The result likes the image below.

However the code is for one cpu only. For the modern machine, the machine has many cores. What I want is to display the cores performance.

So my idea is to use tasks to handle cores.

private PerformanceCounter[] cpuPerformance = new PerformanceCounter[System.Environment.ProcessorCount];

For each core, I want to use a task to do the performance show. The updated code is

public partial class MainWindow : Window
{
    //private ObservableDataSource<Point> dataSource = new ObservableDataSource<Point>();
    private PerformanceCounter[] cpuPerformance = new PerformanceCounter[System.Environment.ProcessorCount];
    private DispatcherTimer timer = new DispatcherTimer();
    private int i = 0;

    public MainWindow()
    {
        InitializeComponent();
    }
    private async void AnimatedPlot(object sender, EventArgs e)
    {
        var t = new Task[cpuPerformance.Length];
        for (int j = 0; j < cpuPerformance.Length; j++)
        {
            t[j] = new Task(() =>
            {
                ObservableDataSource<Point> dataSource = new ObservableDataSource<Point>();
                plotter.AddLineGraph(dataSource, Colors.Green, j+1, "Percentage");
                cpuPerformance[j] = new PerformanceCounter("Processor", "% Processor Time", j.ToString());
                double x = i;
                double y = cpuPerformance[j].NextValue();

                Point point = new Point(x, y);
                dataSource.AppendAsync(base.Dispatcher, point);

                cpuUsageText.Text = String.Format("{0:0}%", y);
                i++;
            }
            );
        }
        await Task.WhenAll(t);
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {

        timer.Interval = TimeSpan.FromSeconds(1);
        timer.Tick += new EventHandler(AnimatedPlot);
        timer.IsEnabled = true;
        plotter.Viewport.FitToView();
    }
}

But I get nothing to display. Help me to figure out what is wrong.

Answer 1

a couple of things:

In your "single core" example you're instantiating PerformanceCounter once. In your multi core you're doing it every time you want to update the graph.

Then again, I wonder if you're using it correctly. It almost seems like you're assuming that these tasks would run on the different cores and that's what makes them count that cores performance.

I'm not accustomed to that library but I'd do this:

1. get rid of the tasks.

2. instantiate the PerformanceCounters once in the constructor

3. read up on how to use the PerformanceCounter class correctly.