OS X Mavericks: What is Activity Monitor?

OS X's Activity Monitor is an essential tool to help you keep your system in good shape. In this report we tell you what it is and some ways to use it.

OS X Mavericks: What is Activity Monitor?


Activity Monitor lets you watch your Mac. It tracks CPU, Memory, Energy, Disk and Network activity. When you launch Activity Monitor you'll find these listed at the top center of the window -- click on any of these buttons to get information about that activity. There's a search bar while the three buttons to the top left enable you to (in order): Quit a selected process; Get information about a process; and run diagnostic tools. If you select Command-2, a floating window appears showing CPU activity. Another tip: Add Activity Monitor to your Dock and it will display system info for you.


The section beneath these controls provides you with more detailed perspective. Various active processes and applications are listed by name alongside the following:

  • %CPU: How much processor power that process is using;
  • CPU Time: The length of time a process has been running;
  • Threads: How many instructions a process is running;
  • Idle Wake Ups: Number of times a process causes the system to execute a task
  • PID: A number assigned to each process by the computer
  • User: OS X can be its own user for essential system processes -- "root, while user-generated processes like using apps are denoted by Mac user name.

You can click on any column to list items in order -- that helps identify applications or processes munching memory, for example.

You can ask Activity Monitor to track other items within the View item in Menu bar, but we won't be looking at these today. To find a little more about any column heading or statistic just move your pointer over the item and leave it there, tool tips will appear with more information


At the bottom of the application window there's a series of diagnostic windows. These change when you click the select one of the tracking items (CPU or Memory, for example) in the top of the window. You can use these tools to understand how busy your system is, how much real and virtual memory it is using, track how much Energy apps are using and track things like the size of the file cache or network activity.

To get an idea as to the health of your drive, tap Disk. This will show you how much data is being written to and read by your disk. Use this to determine which of your apps/processes are using much Virtual Memory. Such information can help you identify potential problems before you hit a wall.

To check system memory, click Memory -- you'll see which of your tasks are eating up memory and how complex those tasks are (by threads used). You usually see Safari Web Content high in this list, reflecting ads and other media found on sites you visit. While Apple's handling of this has improved in Mavericks, Safari appears to keep some content in memory for later use.

Returning to the detailed view the upper part of the info window tells you what the parent process of the process is, its user, the amount of processor (CPU) power it demands and the number of recent hangs (process stutters).

The lower part offers two or three types of information. All deliver information on Memory or Statistics. Memory tells you what memory that process is using in Real, Virtual, Shared and Private terms; while Statistics provides extremely advanced information about process behavior. Some process offer Open Files and Ports, a list of all the files the process is using.

Further reading

Hopefully you now have a slightly better understanding of Activity Monitor. To learn more, please read:

Mavericks Tips and Tricks

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Copyright © 2014 IDG Communications, Inc.

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