CPU Usage in Task Manager using Performance Counters

Question

[My Attempts]

Already went through

1. How to get the CPU Usage in C#? But "_Total" Instance of Processor would give me total consumption of CPU as opposed to specifc application or 'process'

2. In a C# Program, I am trying to get the CPU usage percentage of the application but it always shows 100

3. What exactly is CPU Time in task manager? , explains it but does not say how to retrive this value.

After referring http://social.technet.microsoft.com/wiki/contents/articles/12984.understanding-processor-processor-time-and-process-processor-time.aspx

I got that

TotalProcessorTimeCounter = new PerformanceCounter("Process", "% Processor Time", processName);

has a baseline of (No.of Logical CPU*100) Basically, this does not give me a scale of 100% over CPU consumed.

Tried digging around task manager and found that Task manger->Processor-> CPU Usage is on a scale of 100.

Processor\% Processor Time object does not take process name as input. it only has '_Total' as an input.

[Question]

How do I get this data(CPU consumption) using performance counters over a scale of 100 for a particular process for a multi-core system?

Answer 1

After reading this performance counter document https://social.technet.microsoft.com/wiki/contents/articles/12984.understanding-processor-processor-time-and-process-processor-time.aspx I realized that the correct approach to getting this value is actually to take 100 and subtract the idle time of all processors.

% Processor Time is the percentage of elapsed time that the processor spends to execute a non-Idle thread.

var allIdle = new PerformanceCounter(
    "Processor", 
    "% Idle Time", 
    "_Total"
);

int cpu = 100 - allIdle;

This gives a value very close to what Task Manager displays and perhaps is only different at some points due to rounding or the specific time of when the counter is polled.

Answer 2

If you use this, you can get the same result with the task manager :

cpuCounter = new PerformanceCounter(
        "Processor Information",
        "% Processor Utility",
        "_Total",
        true
    );

Answer 3

This gives me the exact figure you get on Task Manager (in the Details tab), is this what you want?

// Declare the counter somewhere
var process_cpu = new PerformanceCounter(
                                   "Process", 
                                   "% Processor Time", 
                                   Process.GetCurrentProcess().ProcessName
                                        );
// Read periodically
var processUsage = process_cpu.NextValue() / Environment.ProcessorCount;