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Examining the Processor Time Counter

The Processor\% Processor Time counter determines the percentage of time the processor is busy by measuring the percentage of time the thread of the Idle process is running and then subtracting that from 100 percent. This measurement is the amount of processor utilization. Although you might sometimes see high values for the Processor\% Processor Time counter (70 percent or greater depending on your workload and environment), it might not indicate a problem; you need more data to understand this activity. For example, high processor-time values typically occur when you are starting a new process and should not cause concern.



The value that characterizes high processor utilization depends greatly on your system and workload. This chapter describes 70 percent as a typical threshold value; however, you may define your target maximum utilization at a higher or lower value. If so, substitute that target value for 70 percent in the examples provided in this section.

To illustrate, consider that Windows 2000 allows an application to consume all available processor time if no other thread is waiting. As a result, System Monitor shows processor-time rates of 100 percent. If the threads have equal or greater priority, as soon as another thread requests processor time, the thread that was consuming 100 percent of CPU time yields control so that the requesting thread can run, causing processor time to lessen. For a discussion of priority and scheduling, see "Threads in a Bottleneck" later in this chapter.

If you establish that processor-time values are consistently high during certain processes, you need to determine whether a processor bottleneck exists by examining processor queue length data. Unless you already know the characteristics of the applications running on the system, upgrading or adding processors at this point would be a premature response to persistently high processor values, even values of 90 percent or higher. First, you need to know whether processor load is keeping important work from being done. You have several options for addressing processor bottlenecks, but you need to first verify their existence.

If you begin to see values of 70 percent or more for the Processor\% Processor Time counter, investigate your processor's activity further, as follows:

  • Examine System\Processor Queue Length.

  • Identify the processes that are running when Processor\% Processor Time and System\Processor Queue Length values are highest.

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