cf.c

#define UNICODE

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

double f_freq;

double
getsec(void)
{
    LARGE_INTEGER v;
    QueryPerformanceCounter(&v);

    return v.QuadPart / f_freq;
}

int main()
{
    LARGE_INTEGER freq;
    QueryPerformanceFrequency(&freq);

    f_freq = freq.QuadPart;


    double t0, t1;

    FILE *a = fopen("a.txt", "wb");
    fclose(a);

    HANDLE h = CreateFile(TEXT("a.txt"),
                          GENERIC_READ | GENERIC_WRITE,
                          0,
                          NULL,
                          OPEN_ALWAYS,
                          0,
                          NULL);

    CloseHandle(h);

    for (int i=0; i<4; i++) {
        int nloop = 4096;

        t0 = getsec();

        for (int li=0; li<nloop; li++) {
            HANDLE h = CreateFile(TEXT("a.txt"),
                                  GENERIC_READ | GENERIC_WRITE,
                                  0,
                                  NULL,
                                  OPEN_ALWAYS,
                                  0,
                                  NULL);
            CloseHandle(h);
        }

        t1 = getsec();

        printf("%f[usec]\n", ((t1-t0)/nloop)*1000000.0);
    }
}