Why is my C# program faster in a profiler?

by

Luaan posted the solution in the comments above, it’s the system wide timer resolution. Default resolution is 15.6 ms, the profiler sets the resolution to 1ms.

I had the exact same problem, very slow execution that would speed up when the profiler was opened. The problem went away on my PC but popped back up on other PCs seemingly at random. We also noticed the problem disappeared when running a Join Me window in Chrome.

My application transmits a file over a CAN bus. The app loads a CAN message with eight bytes of data, transmits it and waits for an acknowledgment. With the timer set to 15.6ms each round trip took exactly 15.6ms and the entire file transfer would take about 14 minutes. With the timer set to 1ms round trip time varied but would be as low as 4ms and the entire transfer time would drop to less than two minutes.

You can verify your system timer resolution as well as find out which program increased the resolution by opening a command prompt as administrator and entering:

powercfg -energy duration 5

The output file will have the following in it somewhere:

Platform Timer Resolution:Platform Timer Resolution
The default platform timer resolution is 15.6ms (15625000ns) and should be used whenever the system is idle. If the timer resolution is increased, processor power management technologies may not be effective. The timer resolution may be increased due to multimedia playback or graphical animations.
Current Timer Resolution (100ns units) 10000
Maximum Timer Period (100ns units) 156001

My current resolution is 1 ms (10,000 units of 100nS) and is followed by a list of the programs that requested the increased resolution.

This information as well as more detail can be found here: https://randomascii.wordpress.com/2013/07/08/windows-timer-resolution-megawatts-wasted/

Here is some code to increase the timer resolution (originally posted as the answer to this question: how to set timer resolution from C# to 1 ms?):

public static class WinApi
{
    /// <summary>TimeBeginPeriod(). See the Windows API documentation for details.</summary>

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Interoperability", "CA1401:PInvokesShouldNotBeVisible"), System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2118:ReviewSuppressUnmanagedCodeSecurityUsage"), SuppressUnmanagedCodeSecurity]
    [DllImport("winmm.dll", EntryPoint = "timeBeginPeriod", SetLastError = true)]

    public static extern uint TimeBeginPeriod(uint uMilliseconds);

    /// <summary>TimeEndPeriod(). See the Windows API documentation for details.</summary>

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Interoperability", "CA1401:PInvokesShouldNotBeVisible"), System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2118:ReviewSuppressUnmanagedCodeSecurityUsage"), SuppressUnmanagedCodeSecurity]
    [DllImport("winmm.dll", EntryPoint = "timeEndPeriod", SetLastError = true)]

    public static extern uint TimeEndPeriod(uint uMilliseconds);
}

Use it like this to increase resolution :WinApi.TimeBeginPeriod(1);

And like this to return to the default :WinApi.TimeEndPeriod(1);

The parameter passed to TimeEndPeriod() must match the parameter that was passed to TimeBeginPeriod().

More Related Contents:

  1. Best way to reverse a string
  2. What’s the fastest way to read a text file line-by-line?
  3. Is DateTime.Now the best way to measure a function’s performance? [closed]
  4. String vs. StringBuilder
  5. How slow are .NET exceptions?
  6. How costly is .NET reflection?
  7. Performance differences between debug and release builds
  8. C# Sort and OrderBy comparison
  9. How to get object size in memory? [duplicate]
  10. Does C# optimize the concatenation of string literals?
  11. Is String.Contains() faster than String.IndexOf()?
  12. LINQ: Not Any vs All Don’t
  13. Best .NET memory and performance profiler? [closed]
  14. Exact time measurement for performance testing [duplicate]
  15. String interning in .Net Framework – What are the benefits and when to use interning
  16. Float vs Double Performance
  17. Why is LINQ .Where(predicate).First() faster than .First(predicate)?
  18. Performance of “direct” virtual call vs. interface call in C#
  19. SQLite .NET performance, how to speed up things?
  20. How does extern work in C#?
  21. How performant is StackFrame?
  22. How to force a number to be in a range in C#? [duplicate]
  23. How accurate is System.Diagnostics.Stopwatch?
  24. Warm-up when calling methods in C#
  25. Why is processing a sorted array slower than an unsorted array?
  26. Is it better to execute many sql commands with one connection, or reconnect every time?
  27. XmlSerializer Performance Issue when Specifying XmlRootAttribute
  28. Array bounds check efficiency in .net 4 and above
  29. Fastest implementation of log2(int) and log2(float)
  30. Does any one know of a faster method to do String.Split()?

Leave a Comment