Getting % Processor Time for Process By PID

I had to search and search on how to do this, and now hopefully no one else will. It’s fairly easy to get the % CPU Usage for a process using the System.Diagnostics.PerformanceCounter (as long as you remember to sleep a second so you can get the a correct value and divide by the number of CPUs). That looks like this:

PerformanceCounter pc = new PerformanceCounter("Process", "% Processor Time", processName, true);
pc.NextValue();
Thread.Sleep(1000);
int cpuPercent = (int)ppc.PerformanceCounter.NextValue() / Environment.ProcessorCount;

The PerformanceCounter constructor accepts the processName, but it doesn’t accept a process id, so if you had multiple processes with the same name (w3wp, svchost, etc.) you can’t get the value for a specific process easily. If there are multiple processes with the same name running, they’ll have names like “w3wp#1” and “w3wp#2”, where the 1 and the 2 are completely unrelated to ProcessId. I ended up creating this method to get the performance counter process name for a given process. You could be extra fancy and make it an extension method on the Process Class, but this works for now:

private string GetPerformanceCounterProcessName(int pid)
{
   return GetPerformanceCounterProcessName(pid, System.Diagnostics.Process.GetProcessById(pid).ProcessName);
}

private string GetPerformanceCounterProcessName(int pid, string processName)
{
   int nameIndex = 1;
   string value = processName;
   string counterName = processName + "#" + nameIndex;
   PerformanceCounter pc = new PerformanceCounter("Process", "ID Process", counterName, true);

   while (true)
   {
       try
        {
           if (pid == (int)pc.NextValue())
           {
               value = counterName;
               break;
           }
           else
            {
               nameIndex++;
               counterName = processName + "#" + nameIndex;
               pc = new PerformanceCounter("Process", "ID Process", counterName, true);
           }
       }
       catch (SystemException ex)
       {
           if (ex.Message == "Instance '" + counterName + "' does not exist in the specified Category.")
           {
               break;
           }
           else
            {
               throw;
           }
       }
   }

   return value;
}

Then calling it would look like this:

PerformanceCounter pc = new PerformanceCounter("Process", "% Processor Time", GetPerformanceCounterProcessName(PID), true);
pc.NextValue();
Thread.Sleep(1000);
int cpuPercent = (int)ppc.PerformanceCounter.NextValue() / Environment.ProcessorCount;