How to ger RAM and CPU usage of a function?

Question

Lets say, I have a function (or functions) which takes a long time (wall time) to execute, for example:

#include "stdafx.h" #include <math.h> #include <windows.h> void fun() { long sum = 0L; for (long long i = 1; i < 10000000; i++){ sum += log((double)i); } } double cputimer() { FILETIME createTime; FILETIME exitTime; FILETIME kernelTime; FILETIME userTime; if ( GetProcessTimes( GetCurrentProcess( ), &createTime, &exitTime, &kernelTime, &userTime ) != -1 ) { SYSTEMTIME userSystemTime; if ( FileTimeToSystemTime( &userTime, &userSystemTime ) != -1 ) return (double)userSystemTime.wHour * 3600.0 + (double)userSystemTime.wMinute * 60.0 + (double)userSystemTime.wSecond + (double)userSystemTime.wMilliseconds / 1000.0; } } int _tmain(int argc, _TCHAR* argv[]) { double start, stop; start = cputimer(); fun(); stop = cputimer(); printf("Time taken: %f [seconds]\n", stop - start); return 0; }

I would like to measure a CPU load of this function and RAM usage that this function call uses. Is that possible? How can I do this? Im interested in Windows and Linux solutions.

Michael Krelin - hacker · Accepted Answer · 2013-10-19 19:14:12Z

2

On POSIX you can try using getrusage in the manner similar to how you check the wall time. Not sure about windows.

answered Oct 19, 2013 at 19:14

Michael Krelin - hacker

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4 Comments

Brian Brown Over a year ago

yup I know getrusage - I used to measure CPU time. But how about CPU load?

Michael Krelin - hacker Over a year ago

There's no such thing as cpu load of function. It is metric pertaining to cpu.

Brian Brown Over a year ago

So CPU load can be obtained for a process only, not a function itself? How about checking CPU load before and after function call and do the subtraction after?

Michael Krelin - hacker Over a year ago

I think cpu time delta is the metric you're looking for. After all it's about how much cpu your function uses.

Rahul Tripathi · Accepted Answer · 2013-10-19 19:14:08Z

1

There is GetProcessTimes function for windows which can give you the CPU time. Also check the Process Status API

Also there is SIGAR which is platform independent.

On Linux you can try with getrusage

answered Oct 19, 2013 at 19:14

Rahul Tripathi

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17 Comments

Brian Brown Over a year ago

But it all will give me memory per process, not per function call, right?

Michael Krelin - hacker Over a year ago

Memory is not allocated to function. You can either compare before and after or you can link with your own alloc.

Rahul Tripathi Over a year ago

@MichaelKrelin-hacker:- Very correct! Was about to write the same :)

Brian Brown Over a year ago

@Michael Krelin - hacker: OK, I see. What do you mean by 'my own alloc'?

Michael Krelin - hacker Over a year ago

@RahulTripathi, which comes down to cpu time since number of cores is too constant and wall time is too variable ;)

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