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Measure execution cycles of a code..

Posted on 2000-03-10
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Last Modified: 2013-11-15
I am now writing a code in C.
I want to measure execution speed of a code for as high resolution as possible.
I've tried to read PC timer (mc146818) datasheet, its registers can only give 1 second resolution.
Interrupt 1A can only gives 1/100 second resolution.
If it is possible, I want to get the result as a number of clock cycles.
Anybody can point me out about this?

Thanks,
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Question by:wayud
7 Comments
 
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by:alexo
ID: 2604570
If you program under windows, check the following functions:
  QueryPerformanceCounter()
  QueryPerformanceFrequency()

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alexo earned 100 total points
ID: 2604604
Otherwise, there are pentium-specific instructions that you may use to get high resolution timing.
Check RDTSC
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Expert Comment

by:3rsrichard
ID: 2604729
I can suggest two possible solutions
1) If you can run your program on a machine using Windows NT you can use the Administrative Tools - Performance Monitor to get something related to what you want.

The problem with trying to use the hardware timers is that the answer you get will be based on a specific set of hardware.  Another approach is to compile the code, get a listing, and count the number of instructions being executed.  Or if you have a debugger which keeps track of the number of lines executed that would do it.
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Expert Comment

by:Zoppo
ID: 2604951
Hi wayud,

Have you tried 'clock'? It's resolution seems to be at least 20ms. Use it like this:

#include <time.h>

clock_t end, start = clock();
// do lengthy processing
end = clock();

hope that helps,

ZOPPO
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Expert Comment

by:Wyn
ID: 2605210
->If you program under windows, check the following functions:
  QueryPerformanceCounter()
  QueryPerformanceFrequency()
=================================
Fully agree.
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Expert Comment

by:jhance
ID: 2605249
Another approach is to run the instructions in question 10, 100, 1000, etc. times (whatever is needed to get a meaningful result with the timer available) and then scale the result.
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Author Comment

by:wayud
ID: 2606973
Thank you for all of you..
This is what I really need.
I'll try it now.
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