Testing the performance of a C++ app -


I'm trying to find a way to test how long a block of C ++ code is to run Takes up I'm using it to compare code with different algorithms and to compare under different languages, so ideally I need a time in seconds / milliseconds. In Java, I am using something like this: 

  long startTime = System.currentTimeMillis (); Ceremony (); Long Roast Time = System Courantime Milliseau (); Long-term time = stoptime - starttime;

Is there a good way to get accurate time in C ++ (or should I use some other methods of benchmarking?)

Use the best counter available on your platform, back to time for portability. I am using QueryPerformanceCounter, but see comments in other answers.

General advice:

Inner loop must run at least 20 times the resolution to make your clock, resolve error & lt; 5% (Therefore, while using time (your internal loop should run at least 20 seconds)

Repeat these measures, to see if they are continuous

I Using an additional outer loop , ten times running, ignoring the fastest and least slow measurement for calculating average and deviation, deviation is accessible when comparing two implementations. Gets: If you have a 2.0 algorithm +/- 5, and another 2.2 +/- .5 , The difference in calling one of them "fast" is not important (maximum and minimum should still be displayed). Therefore, IMHO should have a valid performance measurement look like this: 

  10000 x 2.0 +/- 0.2 ms (minimum = 1.2, max = 12.6), 10 repetition

If you know what you are doing, clean the cache And thread threads can make your measurement stronger.

However, this is the pifalls There is no more "stable" measurement, less realistic. Data and instruction will vary strongly with the implementation time on the basis of the cash situation. I'm lazy here, using Max = Price to judge the first run penalty, it will not be enough for some scenarios.


Comments

Post a Comment

Popular posts from this blog

python - Overriding the save method in Django ModelForm -

I'm having trouble overriding a ModelForm save method. I get this error I'm: Exception type: TypeErier Exception Value: Save () found an unexpected keyword argument 'committed' My intentions include a form 3 fields Submit several values ​​for, then create an object for each combination of those areas, and to save each object file models.py class collarsult type (models.Model): id = model. AutoField (db_column = 'icontact_result_code_type_id', primary_key = true) callResult = models.ForeignKey ( 'CallResult', db_column = 'icontact_result_code_id') campaign = models.ForeignKey ( 'campaign', db_column = 'icampaign_id') CALLTYPE = models.ForeignKey ( 'CALLTYPE', db_column = 'icall_type_id') agent = models.BooleanField (db_column = 'bagent', default = true) teamLeader = models.BooleanField (db_column = 'bTeamLeader', default = true) active = models.BooleanField (db_column = Django.form...
Read more

html - CSS autoheight, but fit content to height of div -

I have a div in which there are three children- div in the left and middle div: float: left while true: float: true because it is my layout Actually will spoil, I've used ClearFix Hack: .cf {zoom: 1; }. Cf: First,. Cf: {content: ""; Display: Table; }. Cf: After {clear: both; } It still works, but I want to be the right div an indicator. So it should fill 100% of the parent unit of height. How can I complete this? PS is the full code: & Lt; / Div & gt; & Lt; Div class = "mobile_content" & gt; & Lt; H5 & gt; {{Data.titel}} & lt; / H5> & Lt; Table & gt; & Lt; TR & gt; & Lt; Th & gt; Komponist: & lt; / Th & gt; & Lt; TD & gt; {{Data.komponist}} & lt; / TD & gt; & Lt; / TR & gt; & Lt; TR & gt; & Lt; Th & gt; Instrument: & lt; / Th & gt; & Lt; TD & gt; {{Data.instrumente}} & lt; / TD & gt; & Lt; / TR & gt;...
Read more

qt - How to prevent QAudioInput from automatically boosting the master volume to 100%? -

I have been trying to use Qt5 multimedia to record audio with QAudioInput, however, when I see If QAudioInput is started, it increases the master volume of my sound device to 100%. How can I prevent QAudioInput from changing the master volume? My current development platform is Linux with PalsAdio (with flat audio disabled). How can I use QAudioInput : QAudioDeviceInfo device_info = QAudioDeviceInfo :: defaultInputDevice (); QAudio format format; Format.setSampleRate (44100); Format.setChannelCount (1); Format.setSampleSize (16); Format.setCodec ("Audio / PCM"); Format.setSampleType (QAudioFormat :: SignedInt); Format.setByteOrder (QAudioFormat :: LittleEndian); Std :: cout & lt; & Lt; Device_info.deviceName (). ToUtf8 (). ConstData () & lt; & Lt; Std :: endl; QAudioInput * default_device = new QAudioInput (device_info, format); QIODevice * default_io_device = default_device-> Start (); a QAudioInput.setVolume () method is not you I ...
Read more