Measuring CPU Utilization in Windows（测量CPU利用率在Windows）.pdfVIP

Measuring Processor Utilization in Windows and Windows applications Mark B. Friedman Demand Technology Software Introduction. This paper discusses the legacy technique for measuring processor utilization in Windows that is based on sampling. This technique for measuring processor utilization is efficient and generally adequate for capacity planning. However, it lacks the precision performance engineers require for application optimization and tuning, particularly over small measurement intervals. The paper then introduces newer techniques for measuring processor utilization in Windows that are event-driven. The event- driven approaches are distinguished by far greater accuracy, enabling the reconstruction of the precise path that threads, processes and processors take when they execute. Gathering event-driven measurements entails significantly higher overhead, but measurements indicate this overhead is well within acceptable bounds on today’s high powered server machines. As of this writing, Windows continues to report measurements of processor utilization based on the legacy sampling technique. The more accurate measurements that are derived using events are gaining ground, however, and can be expected to supplant the legacy measurements in the not too distant future. While computer performance junkies like me relish the prospect of obtaining more reliable and more precise processor busy metrics, the event-driven measurements do leave several very important issues in measuring CPU utilization unresolved. These include validity and reliability issues that arise when Windows is running as a guest virtual machine under VMware, Zen, or Hyper-V that impact the accuracy of most timer-based measurements. (In an aside, mitigation techniques for avoiding some of the worst measurement anomalies associated with virtualization are discussed.) A final topic concerns c