How to measure time spans in .NET?

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Steve - 29 Apr 2005 21:17 GMT

I used the QueryPerformanceCounter and QueryPerformanceFrequency methods in
my VC++ 6.0 projects to measure correct time spans, for example for timeouts,
how much time takes to execute certain method etc

I wonder whether there is something similar in .NET to measure time spans?

Meantime I still use these methods through DllImport
[DllImport("Kernel32.dll")]
private static extern bool QueryPerformanceFrequency(out long lpFrequency);

I suspect there is better approach then using DllImport. Can anyone suggest
something better?

Thanks

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Kapil Khosla [MSFT] - 02 May 2005 21:37 GMT

> I used the QueryPerformanceCounter and QueryPerformanceFrequency methods in
> my VC++ 6.0 projects to measure correct time spans, for example for timeouts,
[quoted text clipped - 10 lines]
>
> Thanks

Actually, that if you want high precision timing, I still recommend using
explicit Pinvoke the way you describe. In .NET you have access to
System.DateTime structure which is stated as 100 nanoseconds (1 / 10
millionth of a second). If that precision is good enough you should be able
to use that instead.

Thanks,
Kapil

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Carl Daniel [VC++ MVP] - 03 May 2005 02:34 GMT

> Actually, that if you want high precision timing, I still recommend
> using explicit Pinvoke the way you describe. In .NET you have access
> to System.DateTime structure which is stated as 100 nanoseconds (1 /
> 10 millionth of a second). If that precision is good enough you
> should be able to use that instead.

Just to be clear: DateTime has 100 nanosecond resolution. It does not, by
any stretch have 100 nanosecond accuracy or precision. Rather, the
precision and accuracy are on the order of +/- 5-7ms (10-15ms tick time).

-cd

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William DePalo [MVP VC++] - 03 May 2005 02:48 GMT

> Just to be clear: DateTime has 100 nanosecond resolution. It does not,
> by any stretch have 100 nanosecond accuracy or precision. Rather, the
> precision and accuracy are on the order of +/- 5-7ms (10-15ms tick time).

Absolutely right.

FWIW: while there are no guarantees as to minimum latencies on any version
of Windows (except _maybe_ CE, I dunno) you can get the precison down as low
as it will go by bracketing time sensitive sections of code with

timeBeginPeriod(1);

and

timeEndPeriod(1);

It's not at all obvious, but things like the smallest period you can Sleep()
change in the presence of those two inoccuous looking lines.

Regards,
Will

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How to measure time spans in .NET?

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