High resolution timer in .NET

Question

I'd like to do some basic profiling of my code, but found that the DateTime.Now in C# only have a resolution of about 16 ms. There must be better time keeping constructs that I haven't yet found.

Answer 1

The System.Diagnostics.StopWatch class is awesome for profiling.

Here is a link to Vance Morrison's Code Timer Blog if you don't want to write your own measurement functions.

Answer 2

You could call down to the high-resolution performance counter in Windows. The function name is QueryPerformanceCounter in kernel32.dll.

Syntax for importing into C#:

[DllImport("Kernel32.dll")]
private static extern bool QueryPerformanceCounter(out long lpPerformanceCount);

Syntax for Windows call:

BOOL QueryPerformanceCounter(      
    LARGE_INTEGER *lpPerformanceCount
);

QueryPerformanceCounter @ MSDN

Answer 3

Here is a sample bit of code to time an operation:

Dim sw As New Stopwatch()
sw.Start()
//Insert Code To Time
sw.Stop()
Dim ms As Long = sw.ElapsedMilliseconds
Console.WriteLine("Total Seconds Elapsed: " & ms / 1000)

EDIT:

And the neat thing is that it can resume as well.

StopWatch sw = new StopWatch();
foreach(MyStuff stuff in _listOfMyStuff)
{
    sw.Start();
    stuff.DoCoolCalculation();
    sw.Stop();
}
Console.WriteLine("Total calculation time: {0}", sw.Elapsed);

The Stopwatch class will use a high-resolution counter if one is available on your system.

Answer 4

For highest resolution performance counters you can use the underlying win32 performance counters.

Add the following P/Invoke sigs:

[System.Runtime.InteropServices.DllImport("Kernel32.dll")]
public static extern bool QueryPerformanceCounter(out long perfcount);

[System.Runtime.InteropServices.DllImport("Kernel32.dll")]
public static extern bool QueryPerformanceFrequency(out long freq);

And call them using:

#region Query Performance Counter
/// <summary>
/// Gets the current 'Ticks' on the performance counter
/// </summary>
/// <returns>Long indicating the number of ticks on the performance counter</returns>
public static long QueryPerformanceCounter()
{
    long perfcount;
    QueryPerformanceCounter(out perfcount);
    return perfcount;
}
#endregion

#region Query Performance Frequency
/// <summary>
/// Gets the number of performance counter ticks that occur every second
/// </summary>
/// <returns>The number of performance counter ticks that occur every second</returns>
public static long QueryPerformanceFrequency()
{
    long freq;
    QueryPerformanceFrequency(out freq);
    return freq;
}
#endregion

Dump it all into a simple class and you're ready to go. Example (assuming a class name of PerformanceCounters):

long startCount = PerformanceCounter.QueryPerformanceCounter();
// DoStuff();
long stopCount = PerformanceCounter.QueryPerformanceCounter();
long elapsedCount = stopCount - startCount;
double elapsedSeconds = (double)elapsedCount / PerformanceCounter.QueryPerformanceFrequency();
MessageBox.Show(String.Format("Took {0} Seconds", Math.Round(elapsedSeconds, 6).ToString()));