What Is Activity Monitor (or How to Take Your Mac's Pulse)
Pages: 1, 2, 3, 4

For more detail on the hard disk's role in everything, the Disk Activity tab is the place to look. Here you can see exactly how much data is being, or has been, swapped in and out of virtual memory.

The Disk Usage tab is simple enough. It shows you how much of your hard disk space is being used, and how much is free. If the Space Free section of the pie chart is getting worryingly narrow, you probably need to archive some files off the hard disk, prune your music and movie collections, and maybe consider buying another disk to free up more space. Don't forget that the computer depends on the hard disk for virtual memory; if it starts getting too full, the whole system will slow down.

Finally, the Network tab displays a graph of the amount of data going in and out of your machine over the network. Next time you're downloading some huge .torrent file from somewhere, you should see it show up clearly as a spike on this graph.

What Can I Use All of This For?

The most useful things you can do with Activity Monitor are (1) keep a close eye on your computer's performance, and (2) zap applications or processes that have frozen or crashed.

If performance matters, and you like to know what kind of strain the processor is under at all times, you can tell Activity Monitor to display various indicators for you. Under the Window menu you'll find three different CPU usage displays which you can have floating constantly on your desktop if you wish.

What's more, the humble Activity Monitor icon in the Dock can be set to display any of these graphs, or the network activity or memory usage pie chart. Just go to View -> Dock Icon, and select the process you want to monitor on the Dock.

Even if the processor and memory activity don't interest you, the ability to see what kind of network traffic is coming in and out of your machine might be useful, especially if you're still on a dialup connection.

And if you don't even care about network usage, or indeed any other performance indicator, Activity Monitor can still be a useful tool for finding problem apps and force-quitting them.

Tiger users who never paid much attention to Activity Monitor before might want to revisit it for keeping an eye on their Dashboard Widgets. More than once I've spotted a Widget that I don't use much, gobbling up loads of CPU. I can then take the Widget off my active Dashboard until I actually need it.

Much of what Activity Monitor does can also be done with top, a Unix program run in Terminal. If you're happy using command-line apps, top is probably a quicker way to spot the process IDs of misbehaving apps, which can then be stopped using the kill command. But if the command line puts you off, Activity Monitor's friendlier approach might be a better bet.

Giles Turnbull is a freelance writer and editor. He has been writing on and about the Internet since 1997. He has a web site at http://gilest.org.

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Showing messages 1 through 7 of 7.

• wired | active | inactive | free
  2005-10-05 01:41:30  jkkmmck [Reply | View]
  
  
  Was hoping to find out more about these four categories of memory...
• wired | active | inactive | free
  2007-07-18 18:46:45  9us [Reply | View]
  
  
  http://docs.info.apple.com/article.html?artnum=107918
• wired | active | inactive | free
  2005-10-06 19:53:05  mikeunicode [Reply | View]
  
  
  As I understand it, please correct me if I'm wrong...
  
  - Wired: Memory an application or OS requests to be "pinned" or Never swapped out for any reason. You might use this area for interprocess communication or internal system tables, maybe the swap tables.
  - Active memory, normal memory that qualifies the parameters of the LRU( least recently used algorithm ). Recently accessed memory is keept on board, memory that ages by not being accessed has a LRU number and will eventually move to the INACTIVE catagory.
  - Inactive, ready to be swapped out if necessary.
  - Free, in 10.3 Apple seems to have keept open 200 meg of free memory. In 10.4 Apple seems to have bumped that up to 300 meg.
  

• VM versus swap
  2005-10-04 18:33:40  hayne [Reply | View]
  
  
  The article says "The VM Size figure is the amount of hard disk space being used for virtual memory or swap file".
  
  This is glossing over the difference between the virtual memory and the swap file(s). The size shown for VM in Activity Monitor (and in 'top') is the total of the amounts of virtual memory allocated by the processes. But not all of this virtual memory is represented in the swap file(s). The system only writes the portion of VM that is actually used to the swap file(s) when more RAM is needed for something else. So the size of the swap file(s) is generally much less than the size shown for VM in Activity Monitor.
  
  You can see what swap files you have at the moment by looking in the folder /var/vm
  And you can see the total size of the swap files by running the following command in a Terminal window:
  
  /usr/bin/du -hc /var/vm/swap*
• VM versus swap
  2005-10-05 11:51:18  lucbelanger [Reply | View]
  
  
  In Tiger you can just use the sysctl utility on the CLI
  
  sysctl vm
  
  which give a better idea of your VM usage than the "du" solution
  
  vm.loadavg: 0.41 0.67 0.50
  vm.swapusage: total = 128.00M used = 78.31M free = 49.69M
  
  
• VM versus swap
  2005-10-08 01:08:58  sjk [Reply | View]
  
  
  vm.swapusage reminds me of the missing swapmode in pstat (pre-10.4):
  
  % pstat -T
  520/12288 files
  10619 vnodes
  swapmode is not (yet) available under Mach
  
  Anyone know how to obtain the files and vnode info on 10.4 since the pstat command is gone?
• VM versus swap
  2005-10-05 01:29:58  Giles Turnbull | [Reply | View]
  
  
  Good point, hayne, thanks.