A large set of factors determines the normal operating range for each counter in a typical system. You must drive your system through a large number of conditions and develop a sense for normal operating ranges for your equipment. You should record these typical values in log files for future reference. Then, as you make changes to your workload or your hardware, you can refer to your earlier experience as a baseline.
In general, deciding whether or not performance values are acceptable is a subjective judgment that varies significantly with variations in user environments. The values you establish as the baseline for your organization are the best basis for comparison. You should stress test your applications before releasing them and determine the performance thresholds that cause problems. After releasing the application to a live site, you can monitor the performance and take appropriate action if these thresholds are reached.
查了半天告诉我要自己去确认。
参考地址：
http://msdn.microsoft.com/en-us/library/t58h7yx3(v=VS.90).aspx