Sharing the memory
Mac Tip #286/25-April-2007
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 in a tiny space, but to make a three course dinner for 10 you’d better have plenty of room.
Each process running on your Mac takes up a certain amount of RAM. In theory each one takes just as much RAM 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. [Last week’s Tip, How much of the Hard Disk is used?, introduced Activity Monitor.]
The pie chart in the 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.
There’s another 999Mb Active — also supposedly in use. If necessary that can be swapped out to virtual memory.
Virtual memory is hard disk space that can be used temporarily as memory. That’s like sitting at the kitchen table to peel the spuds if the bench is too full to do it there.
699Mb is Inactive. Something was using it, 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 just as Aucklanders suffering gridlock 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, to Quit applications you’re not currently using, or even to work a bit less.
Next week: How much of the Hard Disk is used?