Question

I need to find a bottleneck and need to accurately as possible measure time.

Is the following code snippet the best way to measure the performance?

DateTime startTime = DateTime.Now;  // Some execution process  DateTime endTime = DateTime.Now; TimeSpan totalTimeTaken = endTime.Subtract(startTime); 

Answer 1

No, it’s not. Use the Stopwatch (in System.Diagnostics)

Stopwatch sw = Stopwatch.StartNew(); PerformWork(); sw.Stop();  Console.WriteLine('Time taken: {0}ms', sw.Elapsed.TotalMilliseconds); 

Stopwatch automatically checks for the existence of high-precision timers.

It is worth mentioning that DateTime.Now often is quite a bit slower than DateTime.UtcNow due to the work that has to be done with timezones, DST and such.

DateTime.UtcNow typically has a resolution of 15 ms. See John Chapman’s blog post about DateTime.Now precision for a great summary.

Interesting trivia: The stopwatch falls back on DateTime.UtcNow if your hardware doesn’t support a high frequency counter. You can check to see if Stopwatch uses hardware to achieve high precision by looking at the static field Stopwatch.IsHighResolution.