Activity Monitor: View your computer’s processor activity

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View your computer’s processor activity

Most of the time your computer’s processor, or CPU, is using only a small percentage of its processing power. However, when you use applications that require intensive calculations, or if you use multiple applications at one time, your processor may be working near its maximum capacity.

You can use Activity Monitor to see how different types of processes are using your processor’s time. You can view your processor’s current use or a recent history of its use.

View the current processor activity

You can view your computer’s current processor activity in a window or in tiny bar graphs. Activity Monitor displays one graph for each processor in your computer.

  1. Open Activity Monitor, in the Utilities folder in Launchpad.
  2. Do one of the following:
    • Choose Window > CPU Usage.

      The graphs appear in a separate window.

    • Choose Window > Floating CPU Window.

      The graphs appear in the bottom-left corner of the screen. You can drag them wherever you want. You can also choose whether to display the graphs horizontally or vertically.

View processor activity over time in the Activity Monitor window

In the Activity Monitor window, you can view CPU graphs that show your computer processor’s use over time. If your computer has four or fewer processor cores, you see multiple graphs, one for each processor core. If your computer has more than four processor cores, you see a single graph with the aggregate use.

  1. Open Activity Monitor, in the Utilities folder in Launchpad.
  2. Click CPU in the bar at the bottom of the Activity Monitor window.

    The following types of processes are displayed:

    Option Description
    % User: The percentage of the CPU’s time that’s being used by applications and processes that you opened or by the subprocesses that those applications and processes opened.
    % System: The percentage of the CPU’s time used by the processes opened by Mac OS X or the subprocesses opened by those processes.
    % Idle: The percentage of the CPU’s time that isn’t being used.

View processor activity over time in a separate window

In a separate window, you can view CPU graphs that show your computer processor’s use over time. You see one graph for each processor core, no matter how many processor cores you have.

  1. Open Activity Monitor, in the Utilities folder in Launchpad.
  2. Choose Window > CPU History.

    A new window opens with the graphs.

View processor activity over time in the Dock

In the Dock, the icon for Activity Monitor can display CPU graphs that show your computer processor’s use over time. If your computer has four or fewer processor cores, you see multiple graphs, one for each processor core. If your computer has more than four processor cores, you see a single graph with the aggregate use.

  1. Open Activity Monitor, in the Utilities folder in Launchpad.
  2. Choose View > Dock Icon > Show CPU History.

Change the color of items in the CPU graph

You can change a CPU graph’s colors in the Activity Monitor window. The colors are used in the CPU graphs that appear in the Activity Monitor window, in Activity Monitor’s Dock icon, or in a separate window.

  1. Open Activity Monitor, in the Utilities folder in Launchpad.
  2. Click CPU in the bar at the bottom of the Activity Monitor window.
  3. Click the color box next to each item.
Last Modified: Sep 3, 2015
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