In this PowerUp Miraz Jordan monitors her Mac’s activity. First published June 2006. Some details may be a bit dated.
I work my Macs hard. Every single day my MacBook Pro handles email, web and newsfeeds, PDFs, text documents, Word documents and Excel spreadsheets, screenshots, photos and timesheets. It plays my music and podcasts, transfers files to websites, shares my Bookmarks with Del.icio.us and sometimes plays movies from the Internet or DVDs.
It handles my accounts, address book and calendar. It records sound, reaches through the network to control my Mac mini. From time to time it shows me what’s in the night sky.
I often require it to carry out a dozen of these tasks at the same time, and sometimes I worry that it’s all too much, so I use Activity Monitor in the Applications > Utilities folder to keep an eye on what’s going on.
You know if you open up an application such as Safari, but your Mac may be carrying out other processes silently such as checking whether iCal has any alarms ready to fire or if a spelling suggestion is needed.
Activity Monitor can show All Processes or group them in various ways from the pop-up at top right of the window. Click on a column heading to sort by that column.
Using CPU and memory
While processes are running they take up some of the CPU time and some of the RAM (memory). These numbers fluctuate. Set iTunes to playing, for example, and watch it use more and less of the CPU as the music changes.
Some applications gradually suck up all the Real Memory if you leave them running, even if they aren’t actually doing anything. Try sorting on the Real Memory column and keep a watch on how the memory is being used.
Force Quit a process
Sometimes an application or other process hangs and you want to Force Quit it.
The Apple menu item or a key combination will do that, but you can also do it from the Activity Monitor.
Click on the name of the process, then click the Quit Process button You are unable to Quit some processes initiated by the System.
Sharing the memory
The best money you can spend on a computer is to give it more RAM, the working space for your computer. It’s like a kitchen bench: you can easily make a cheese sandwich on a tiny bench, but to make a three course dinner for 10 you’d better have plenty of room.
Each process you have running takes up a certain amount of RAM. In theory, with Mac OS X, it takes just as much as it needs, when it needs it and then gives it back.
But just as in real life where the last family member to make a sandwich didn’t put the bread away or wash the knife, some processes aren’t so well behaved.
Click on the System Tab near the bottom of the Activity Monitor window to see how the computer’s memory is being used.
The pie chart in my screenshot shows that I have 2 Gigabytes of RAM.
The list on the left shows almost 175Mb is being used for ‘wired’ memory — that’s memory that’s actually in use. It can’t be swapped out for virtual memory.
Virtual memory is hard disk space that can be used temporarily as memory. That’s like using the kitchen table to peel the spuds if the bench is too full to do it there.
There’s another 999Mb also supposedly in use. If necessary that can be swapped out to virtual memory.
699Mb is inactive. Something was using that, but not right this minute. That can be swapped (paged) to virtual memory. The 1.83Gb figure is the total of the left column. There’s a meagre 171Mb actually free.
Memory is a shared resource on your Mac. The applications you have running should not all need the whole lot at the same time, just as in a city it’s not expected that every driver will be on the same road at the same moment.
But every time Aucklanders suffer gridlock they know they need more roads. Activity Monitor can show you if you’re running more applications at one time than your Mac can comfortably handle. The solution may be more RAM, a newer Mac, or even to work a bit less.
First published in Macguide magazine Issue #27 May / June 2006 and republished with permission. This article may have been modified from the original.