Tip of the day: Use Task Manager to track memory usage

Yesterday I explained how to use Task Manager to monitor CPU performance. (For a refresher course on Task Manager, see Get to know Task Manager.) Today I explain how to use Task Manager to keep track of random access memory (RAM) usage.

First, a word of caution: Some people assume that the goal of memory management is to leave as much memory free as possible. (That attitude is especially prevalent among those who spent a long time working with the notoriously resource-challenged Windows 95/98/Me family.) In fact, for best performance your goal should be to make maximum use of RAM. Empty RAM does you no good. Windows can swap data in and out of RAM very quickly, so if memory is free, the cache manager tries to fill it up with as much data as possible. Likewise, a well-written program can and should load as much data into memory as possible so that it can respond quickly when you make a request. A really well written program will know how to discard data it doesn’t need when the system asks for extra RAM for another task.

Disk access, on the other hand, is far slower than a call to memory. So the situation you want to avoid is running so many programs at once that you run out of RAM and have to start swapping data from fast memory to the slow disk-based page file.

To see how much memory is in use, open Task Manager and click the Performance tab.

The data shown here can be confusing, and in fact much of it is completely irrelevant. For the most part, you should look at only two values here. Under the Physical Memory heading, look at the value that appears to the right of Total. In this example, I’ve got 261,616K (roughly 256 MB) of physical RAM installed. Your value may be different, and if your system uses an inexpensive “shared RAM” video adapter you may discover that you have less physical RAM than you thought.

Now look at the first value under the Commit Charge heading. The number to the right of Total here indicates how much RAM is actually in use by programs and processes. If the number here is bigger than the amount of physical RAM, your system has been forced to swap data to disk, and that’s the cause of the current performance problem.

To see how much RAM is in use by each program or process, click the Processes tab and then click the Mem Usage heading twice to sort the list in descending order. You can use this information to decide which programs to close so that you can return to normal performance. (Remember, though, it’s perfectly OK for a process to use a large amount of RAM if you’ve got the physical RAM to spare. Don’t just start closing programs that use large amounts of RAM!)

If you find yourself regularly using more memory than you have physical RAM (in other words, if the Total Commit Charge is consistently more than Total Physical RAM), it’s time to order a memory upgrade.