What Do The Numbers Mean In Windows Task Manager?

[treis]

Looking at the performance tab of Windows Task Manager I am unsure what a couple of the numbers mean. CPU Usage is obvious but I don’t know what the others mean. What is PF Usage, Totals, Physical Memory, Commit Charge and Kernal Memory?

[CaveMike]

@TaskMgr Help

Performance fields overviewThe Performance tab displays a dynamic overview of your computer’s performance. Click one of the following for more information:

CPU Usage A graph indicating the percentage of time the processor is working. This counter is a primary indicator of processor activity. View this graph to see how much processing time you are using. If your computer seems to be running slowly, this graph could display a higher percentage.

CPU Usage History A graph showing how busy the CPU has been over time. The sampling displayed in the graph depends on the value you select for the Update Speed on the View menu. Updates occur with these possible values: High = twice per second; Normal = once every two seconds; Low = once every four seconds; Paused = display doesn’t automatically update.

PF Usage The amount of paging file being used by the system. If your computer is running near the maximum, you can increase the page file size.

Page File Usage History Graph depicting the amount of page file used over time. The sampling displayed in the graph depends on the value you select for the Update Speed on the View menu.

Totals Totals for the number of handles, threads, and processes running on the computer.

Commit Charge (K) Memory allocated to programs and the operating system. Because of memory copied to the paging file, called virtual memory, the value listed under Peak may exceed the maximum physical memory. The value for Total is the same as that depicted in the Page File Usage History graph.

Physical Memory (K) The total physical memory, also called RAM, installed on your computer. Available represents the amount of free memory that is available for use. The System Cache shows the current physical memory used to map pages of open files.

Kernel Memory (K) Memory used by the operating system kernel and device drivers. Paged is memory that can be copied to the paging file, thereby freeing the physical memory. The physical memory can then be used by the operating system. Nonpaged is memory that remains resident in physical memory and will not be copied out to the paging file.

There is some info in the Task Manager help. I have attached part of it above. I suspect, however, that you are less interested in what these columns stand for and more interested in how would one use them?

For example, you mentioned page-file (PF) usage. The page-file is a special file on your hard-drive that acts as a drip-pan for your memory. Windows will let you run a lot of programs at the same time, even if you don’t have enough RAM to do it. If you run out of memory, Windows will clear up some free space by moving stuff into the page-file. The more stuff it moves, the bigger the page-file gets, and the less free space you have on your hard-drive. Since the page-file is a special file, the space for it is reserved when Windows boots. It won’t shrink or grow like a normal file. You can use this info from Task Manager to make sure that your page-file is big enough to hold what you need without being too big to waste space.

Some of the other fields are useful for diagnosing a buggy program. Developers often use these columns to debug their own programs. For example, a developer might run their program overnight. In the morning, they would check the memory usage to see if their program is “leaking” memory – in other words, reserving memory and then forgetting to unreserve it later when the memory is no longer needed.

I can try to explain any of the other fields too if you want.

[El_Zagna]

Hey, treis, yours is a question I’ve wanted to ask for some time. My CPU Usage graphs have both red and green lines. Why two? I don’t have two CPS’s.

Also my PF Usage graph hovers at 335 MB unless I’m doing graphic intense stuff. Is 335 MB where it should be?

[CaveMike]

@El Zagna

Hey, treis, yours is a question I’ve wanted to ask for some time. My CPU Usage graphs have both red and green lines. Why two? I don’t have two CPS’s.

Also my PF Usage graph hovers at 335 MB unless I’m doing graphic intense stuff. Is 335 MB where it should be?

When you have Task Manager open and you are on the Performance tab, there is a menu option: View->Show Kernel Times. If this option is enabled, the graph will include red and green lines. The green lines show total CPU usage and the red lines just show total kernel CPU usage. The kernel is a subset of Windows that makes up the core of the operating system. By enabling the red lines, you can see how much of your CPU is dedicated to kernel functions versus regular application functions. It can be useful when debugging a Windows driver. Also, if my computer seems unresponsive, I will take a peek at the red line. If there is a lot of red line CPU, it often means that an application invoked a kernel function that is eating up CPU and making the system unresponsive. It also means that it is unlikely that the app will respond until the operation is done (or times out). On the other hand, if there is not a lot of red line CPU, it usually means that the CPU is just getting eaten up by the app and it should be easy enough to kill it.

As far as the 335 MB, I don’t think there is a fixed answer. You just want your page-file to be big enough for your heaviest days. You can check the page-file size in Control Panel->System, Advanced Tab, Performance Settings button, Advanced tab again, page-file size is listed at the bottom (this is on Windows XP). As long as this is big enough to handle your graphics apps, you should be fine. I believe if it is not enough, then Windows will pop up a message about closing some applications, etc. Only then do you really need to grow the page-file size and reboot. Otherwise, you can ignore it. I am assuming that your hard-drive is much bigger than 335 MB, so you are not tight on size.