Is DateTime.Now the best way to measure a function's performance? [closed]

Answer 1

If you want something quick and dirty I would suggest using Stopwatch instead for a greater degree of precision.

Stopwatch sw = new Stopwatch();
sw.Start();
// Do Work
sw.Stop();

Console.WriteLine("Elapsed time: {0}", sw.Elapsed.TotalMilliseconds);

Alternatively, if you need something a little more sophisticated you should probably consider using a 3rd party profiler such as ANTS.

Answer 2

This article says that first of all you need to compare three alternatives, Stopwatch, DateTime.Now AND DateTime.UtcNow.

It also shows that in some cases (when performance counter doesn't exist) Stopwatch is using DateTime.UtcNow + some extra processing. Because of that it's obvious that in that case DateTime.UtcNow is the best option (because other use it + some processing)

However, as it turns out, the counter almost always exists - see Explanation about high-resolution performance counter and its existence related to .NET Stopwatch?.

Here is a performance graph. Notice how low performance cost UtcNow has compared to alternatives:

The X axis is sample data size, and the Y axis is the relative time of the example.

One thing Stopwatch is better at is that it provides higher resolution time measurements. Another is its more OO nature. However, creating an OO wrapper around UtcNow can't be hard.

Answer 3

These are all great ways to measure time, but that is only a very indirect way to find bottleneck(s).

The most direct way to find a bottneck in a thread is to get it running, and while it is doing whatever makes you wait, halt it with a pause or break key. Do this several times. If your bottleneck takes X% of time, X% is the probability that you will catch it in the act on each snapshot.

Here's a more complete explanation of how and why it works

Answer 4

Visual Studio Team System has some features that may help with this problem. Essentially you can write unit tests and mix them in different scenarios to run against your software as part of a stress or load test. This may help to identify areas of code that impact your applications performance the most.

Microsoft' Patterns and Practices group has some guidance in Visual Studio Team System Performance Testing Guidance.

Answer 5

Use the System.Diagnostics.Stopwatch class.

Stopwatch sw = new Stopwatch();
sw.Start();

// Do some code.

sw.Stop();

// sw.ElapsedMilliseconds = the time your "do some code" took.

Answer 6

The way I use within my programs is using the StopWatch class as shown here.

Stopwatch sw = new Stopwatch();
sw.Start();


// Critical lines of code

long elapsedMs = sw.Elapsed.TotalMilliseconds;