Tools to monitor memory usage in Windows 7

To help you to appreciate the memory usage information in Windows 7 and to put the evolution of Windows resource monitoring into perspective, I thought I would begin by taking a quick look back at Windows 9x’s Resource Meter. Once you have Resource Meter up and running, you can hover the mouse pointer over the icon and you will see a pop-up display that breaks down the amount of available system resources into its three categories: System, User, and GDI, as shown in Figure A.

Figure A

Hovering the mouse pointer over the Resource Meter icon produces a display of the currently available system resources in three categories.

If you double-click the icon, you will see the Resource Meter dialog box, shown in Figure B. As you can see, this display used three gas gauge-like monitors to show you the amount of available system resources in each category.

Figure B

The Resource Meter’s display uses three gas gauge-like monitors to show you the amount of available system resources in each category.

Because resource management was horrible in the Windows 9x days, system crashes were inevitable. If you kept your eye on the Resource Meter icon, you could literally watch the amount of system resources depleted as you worked. As you can see in Figure C, the green bars would move down and change to yellow and then to red right before the system crashed.

Figure C

This is the evolution of a system crash caused by the depletion of system resources.

The Task Manager Performance tab

When you compare the Performance tab in Windows 7’s Task Manager to the one in Vista, as shown in Figure D, you’ll notice a few changes in the statistics sections. First, in the Physical Memory section, you’ll see that there is now a measurement showing the amount of available memory. While in Vista you can easily deduce the amount of available memory by subtracting the Total value from the Cached value. It is nice to be able to tell at a glance just how much physical memory is currently available to the system.

Figure D

Comparing Vista’s and 7’s Performance tab reveals a few slight, but noteworthy, changes.

Of course, the Total entry shows the amount of RAM installed in the system. The Cached entry indicates the amount of physical memory used recently for system resources. (This memory will remain in the cache in case the system resources are needed again, but it’s available should other operations need it.) The new Available entry indicates the amount of physical memory that is currently not being used. The Free entry indicates the amount of memory being used in the cache that does not contain useful information.
The Kernel Memory section now shows only the amount of Paged and Nonpaged memory. The Paged and Nonpaged entries break down the total amount of memory being used by the kernel and show you how much is coming from virtual memory and how much is coming from physical memory, respectively. The Total entry, which was essentially useless here, has been removed.
In the System section, you’ll find the same measurements found in Vista; however, the Page File item has been renamed to Commit. (Windows XP called this same measurement the Commit Charge and dedicated an entire section to it.) This measurement still shows Page File usage. Here, the first number indicates the total amount of physical and virtual memory currently in use, while the second number indicates the total amount of physical and virtual memory available on your computer.
The Handles and Threads entries are rather obscure and are actually sub-objects of processes. The Handles entry shows the number of object identifiers, or handles, that are currently in use by all the running processes. The Threads entry actually refers to the number of subprocesses running inside larger processes. The Processes entry, of course, represents the number of currently running processes. As you know, you can see each of the currently running processes by selecting the Processes tab.
The Up Time entry is still a nice piece of information that shows the amount of time that has passed since the computer has been restarted.

The Resource Monitor Memory tab

To access the Resource Monitor, just click the button on the Performance tab in Windows 7’s Task Manager. Then, select the Memory tab in the Resource Monitor. When you do, you’ll see the newly revamped interface, shown in Figure E. While the three graphs on the side are a nice new feature and show regularly updated graphs, the Physical Memory usage chart is stunning in that it provides an extremely intuitive picture of memory usage.

Figure E

The Physical Memory usage chart provides a very easy to understand picture of memory usage.

If you do the math, you can see the chart accounts for every bit of memory installed in the system. Table A identifies each section of the chart. If you subtract the amount reserved for hardware, you get the Total. If you add the Standby and Free, you get the Available to Programs total.

Table A

Hardware Reserved	Memory that is reserved for use by the BIOS and some drivers for other peripherals.
In Use	Memory used by process working sets, drivers, nonpaged pools, and operating system functions.
Modified	Memory whose contents must be to disk before it can be used for another purpose.
Standby	Memory that contains cached data and code that is not actively in use.
Free	Memory that does not contain any valuable data and that will be used first when processes or the operating system needs more memory.