how to calculate total '% Processor Time ' ,

Hi

Please try this:

var managementObjectSearcher = new ManagementObjectSearcher(@"\\\root\CIMV2", "SELECT * FROM Win32_PerfFormattedData_PerfOS_Processor WHERE Name=\"_Total\"");

ManagementObjectCollection managementObjectCollection = managementObjectSearcher.Get();
ManagementObject managementObject = managementObjectCollection.Cast().First();

int totalTime = managementObject["PercentProcessorTime"];

For this code to work you need to add reference of System.Management.dll to your project.

Regards
AJ