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Precise duration measurement

, 27 Dec 1999
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A simple class that provides high precision timing.
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    Here is a simple class used to measure the duration of functions or code parts (from some microseconds to milliseconds) using the Windows high precision timer.

    This class is very easy to use. The following code measure the duration of the Foo function:

        CDuration timer;
    
        timer.Start();
        Foo();
        timer.Stop();
    
        cout << "Foo duration: " << timer.GetDuration()/1000.0 << " milliseconds" << endl;
    

    The GetDuration() method returns the number of microseconds between calls to Start() and Stop(). This value depends on the precision of the internal timer. In a multitasking operating system like Windows, it is difficult to make very accurate duration measurement. Thus, measurement less than a few milliseconds will be correct, but longer measurement could have a difference of a tenth of a millisecond or more because of tasks switching.

    The constructor implements a calibration procedure so the following code will return 0 milliseconds:

        CDuration dur;
    
        dur.Start();
        dur.Stop();
    
        cout << "Zero duration: " << dur.GetDuration()/1000.0 << " milliseconds" << endl;
    

    If you really need no task switching during a long time, you could increment the process and thread priority in the Start() method and decrement it in Stop() .

    License

    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here

    About the Author

    Laurent Guinnard

    Switzerland Switzerland
    No Biography provided

    Comments and Discussions

     
    Questionlicense PinmemberJohnWallis4210-Jun-09 17:40 
    AnswerRe: license PinmemberLaurent.Guinnard1-Nov-09 7:01 
    Questionhow come it wont compile? Pinmemberchefmannyd16-May-09 8:05 
    AnswerRe: how come it wont compile? PinmemberDave Cross20-Jul-09 0:49 
    QuestionCan I write my own profilling code Pinmemberaamerqureshi12-Mar-07 1:02 
    GeneralTerrific.. but could use a few small functions Pinmemberhannahb3-Aug-06 6:14 
    Questionseconds or milliseconds ? PinmemberStlan25-Apr-05 3:55 
    AnswerRe: seconds or milliseconds ? PinmemberStlan25-Apr-05 3:56 
    GeneralExcellent PinmemberSimon Hughes2-Jun-04 1:56 
    GeneralThe best! PinmemberDlt7520-May-04 20:21 
    GeneralAccurate timing PinmemberBernhard Hofmann9-Sep-03 21:59 
    Hi
     
    A long time ago (Feb. 1999), I read an article by Chih-Hao Tsai of the University of Illinois at Urbana-Champaign.
     
    He was using Windows 95, so the high res timer wasn't available. Also, if anyone needs a precise timer on an older OS, they might be interested in the following. He used the multi-media timer (in winmm.lib) to get a millisecond accurate timer.
     
    His article is unfortunately no longer where it once was (http://casper.beckman.uiuc.edu/~c-tsai4/cogsci/millisecond.html). His summary was as follows:
     
    "Virtually all cognitive psychology experiments require a millisecond resolution timing routine. In the good old MS-DOS days, it was easy to achieve this by increasing the frequency of hardware interrupt IRQ0 (int 8h), at the cost of increased instability of the whole system. Today, most people have already moved from MS-DOS to Windows 95 operating system. Since Windows 95 a such a complex system, in general a programmer cannot (or is not allowed to) intrude into lower levels of the system.
     
    In fact, both the standard C run-time library and the Win32 API provide some timing functions. But we do not know how accurate they are. Two run-time library functions and two Win32 API functions from Microsoft Visual C++ Version 4.0 were tested on a Windows 95 machine with a standardized procedure for their quality (in terms of the resolution they can achieve). It was found that the two run-time library functions were basically at the same precision level: 18.2 Hz (resolution = 55 ms). The two Win32 API functions performed better than the run-time library functions, but only one of them reached near-millisecond resolution. It was concluded that only the Multimedia Timer is qualified to be used in psychological experiments.
    "
     
    I still have the code samples he wrote to test the timers as well if anyone's interested.
    GeneralCalling Start() Causes a Thread Switch PinmemberMikeAThon20-Feb-03 15:08 
    GeneralRe: Calling Start() Causes a Thread Switch Pinmemberpeterchen25-Apr-05 6:08 
    GeneralRe: Calling Start() Causes a Thread Switch PinmemberToby Opferman15-Aug-06 16:39 
    General5/5 PinmemberRalph Wetzel8-Jan-03 10:42 
    GeneralExcellent! PinmemberNitron12-Nov-02 8:16 
    GeneralSimple and concise I like it. PinmemberAnonymous4-Mar-02 9:46 

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