Monday, August 24, 2009

System Performance - CPU Counters

  • % Processor Time.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.
  • System : Processor Queue Length. Oddly enough, this processor counter shows up under the System object, but not without good reason. There is only 1 queue for tasks that need to go to the processor, even if there is more than one CPU. Thus, counter provides a measure of the instantaneous size of the queue for all processors at the moment that the measurement was taken. The resulting value is a measure of how many threads are in the Ready state waiting to be processed. When dealing with queues, if the value exceeds 2 for a sustained period, you are definitely having a problem with the resource in question.
  • Processor : % User Time. The value of this counter helps to determine the kind of processing that is affecting the system. Of course the resulting value is the total amount of non-idle time that was spent on User mode operations. This generally means application code.

  • Processor : %Privilege Time. This is the amount of time the processor was busy with Kernel mode operations. If the processor is very busy and this mode is high, it is usually an indication of some type of NT service having difficulty, although user mode programs can make calls to the Kernel mode NT components to occasionally cause this type of performance issue.

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