Running Tasks and Applications

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Each application runs one or more tasks in the Task Manager. You should close unused tasks to free up system resources. Some tasks are required to operate Windows NT, and others are applications themselves. Windows NT services are also shown as tasks, but cannot be closed with the Task Manager. Windows NT services should be closed using the Services icon in the Control Panel. (See the preceding section, “Running Windows NT Services.”)

You should close applications when they are not in use or at least minimized. Surprisingly, an application running in a window takes up significantly more memory than the same application that is minimized. When moving from one application to another, do not use the Alt+Tab or the Taskbar button; they just move the selected application to the foreground.

To see the effects of memory consumption of full-screen versus minimized applications, follow these steps:

1.	Start the Task Manager and view the Processes tab.
2.	Select Start, Programs, Accessories, WordPad.
3.	With the application maximized, return to the Task Manager. Note the amount of memory being used from the Mem Usage column.
4.	Minimize WordPad and compare the memory usage in the Task Manager.

Not all applications run as effectively under Windows NT Workstation 4.0. DOS, 16-bit, 32-bit, OS/2, and Unix applications are treated very differently on the system. A 32-bit application designed to run on Windows NT performs better and more efficiently than any other type. That is because only 32-bit applications run in the main subsystem without additional effort. 32-bit applications are designed to take advantage of the Pentium processor, and they are most likely multithreaded. For all other types, Windows NT emulates their native operating system environment. This emulation requires more system resources to maintain, but offers better compatibility.

All DOS applications are run in an NTVDM. This is a Windows NT Virtual DOS Machine that represents all the aspects of single computer. The DOS application believes it is the only application running on the computer. All 16-bit applications run in a WOW on top of an NTVDM. WOW stands for Windows on Windows. The WOW is meant to represent Windows 3.1/3.11.

OS/2 and Unix-based applications run in their respective subsystems that start along with the application. The Task Manager shows these NTVDMs and other subsystems in use along with their memory requirements.

Running applications as foreground tasks will have a higher priority on the workstation and seem to be more responsive to the user. Windows NT Workstation 4.0 offers a foreground/background priority setting. All applications are written with a set of base priorities for each of its threads. The base priority of the thread is used to determine how much CPU time that it can have in relation to other threads. A thread running at a priority of 12 runs before a thread with a priority of 8. Windows NT dynamically modifies the priority of threads to ensure all threads get some time on the CPU.

Priorities range from 1 to 31 and are set by the programmer. A normal thread level is 8 for most user-based application tasks. Most operating system tasks run at a priority above 15. Although the user cannot change the exact value of the thread’s priority, it can be boosted.

A simple method to change the overall responsiveness of foreground versus background tasks is to set the Application Performance Boost found in the System icon’s Performance tab. A Maximum boost increases the thread’s priority by two levels when running in the foreground. The Minimum boost increases the priority by one and the None boost does not increase the thread priority at all (see Figure 6.20).

You can boost individual applications by using the command line. The command line is accessed through the Start menu by choosing Command Prompt in the Programs menu. An alternative way is to use Start/Run and type CMD.

Four start command switches used to change the priority of a given application. They all use the Start command and are listed in Table 6.14.

To start the Notepad application with a priority of 13, follow these steps:

1.	From the Start menu, choose Programs, Command Prompt.
2.	Type Start/High Notepad.exe.

You can see a process’ current priority with utilities such as the Process Monitor and Process Viewer from the Windows NT Resource Kit. See the section entitled “Using Resource Kit Utilities” earlier in this chapter. The only situation in which the option of running applications in a higher priority level will manifest itself is on a system where the CPU is very busy. The same example could be repeated using the /Realtime switch.