rw-win.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;
}

void test(int SZ)
{
    char data[SZ];
    LARGE_INTEGER freq;
    QueryPerformanceFrequency(&freq);

    f_freq = freq.QuadPart;


    double t0, t1;

    FILE *a = fopen("a.txt", "wb");
    fwrite(data, 1, SZ, a);
    fclose(a);

    HANDLE h = CreateFile(TEXT("a.txt"),
                          GENERIC_READ | GENERIC_WRITE,
                          0,
                          NULL,
                          OPEN_ALWAYS,
                          0,
                          NULL);
    for (int i=0; i<4; i++) {
        int nloop = 4096;

        t0 = getsec();

        for (int li=0; li<nloop; li++) {
	    DWORD rdsz;
	    OVERLAPPED ov;
	    memset(&ov, 0, sizeof(ov));
	    ReadFile(h, data, SZ, &rdsz, &ov);
        }

        t1 = getsec();

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


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

        t0 = getsec();

        for (int li=0; li<nloop; li++) {
	    DWORD rdsz;
	    OVERLAPPED ov;
	    memset(&ov, 0, sizeof(ov));
	    WriteFile(h, data, SZ, &rdsz, &ov);
        }

        t1 = getsec();

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

    CloseHandle(h);
}


int main()
{
    test(1);
    test(1024);
    test(1024*1024);
}