This answer to a related question might work:
private static string GetProcessInstanceName(int pid)
{
PerformanceCounterCategory cat = new PerformanceCounterCategory("Process");
string[] instances = cat.GetInstanceNames();
foreach (string instance in instances)
{
using (PerformanceCounter cnt = new PerformanceCounter("Process",
"ID Process", instance, true))
{
int val = (int) cnt.RawValue;
if (val == pid)
{
return instance;
}
}
}
throw new Exception("Could not find performance counter " +
"instance name for current process. This is truly strange ...");
}