I want record the memory usage of my program. Here is a example.

#include <stdio.h>
#include <windows.h>
#include <psapi.h>

void getMemInfo(){
    PROCESS_MEMORY_COUNTERS_EX pmc;
    GetProcessMemoryInfo(GetCurrentProcess(), (PROCESS_MEMORY_COUNTERS *)&pmc, sizeof(pmc));
    SIZE_T virtualMemUsedByMe = pmc.PrivateUsage;
    SIZE_T physMemUsedByMe = pmc.WorkingSetSize;
    printf("%ld, %ldn", virtualMemUsedByMe, physMemUsedByMe);
}
int main()
{
    double a[1000];
    
    getMemInfo();
    double *b = malloc(sizeof(double)*1000);
    
    getMemInfo();
    free(b);

    getMemInfo();
    return 0;
}

I compile it and run it three times;

Well. Now I have few questions.

• Why does the usage of my program [or my program output] change every time? Did I use the wrong parameters of pmc?
• How to record the memory usage of c program in time before and after allocating new memory?
• I want to optimize a c project. So I should use which parameter of pmc as a benchmark？

Refer:

• Collecting Memory Usage Information For a Process
• c++ – How to determine CPU and memory consumption from inside a process – Stack Overflow