// pf_test.c - Page Fault Investigation
#include "hakmem.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define SIZE (2 * 1024 * 1024)

static void get_pf(unsigned long *soft, unsigned long *hard) {
    FILE* f = fopen("/proc/self/stat", "r");
    if (!f) { *soft = 0; *hard = 0; return; }
    
    unsigned long minflt = 0, majflt = 0;
    (void)fscanf(f, "%*d %*s %*c %*d %*d %*d %*d %*d %*u %lu %*u %lu",
                 &minflt, &majflt);
    fclose(f);
    *soft = minflt;
    *hard = majflt;
}

void test_hakmem() {
    unsigned long pf_before, pf_after, hard_before, hard_after;
    
    printf("\n=== hakmem Test ===\n");
    hak_init();
    
    get_pf(&pf_before, &hard_before);
    
    for (int i = 0; i < 10; i++) {
        void* buf = hak_alloc_cs(SIZE);
        memset(buf, 0xEF, SIZE);
        hak_free_cs(buf, SIZE);
    }
    
    get_pf(&pf_after, &hard_after);
    
    printf("Page Faults: %lu (soft), %lu (hard)\n",
           pf_after - pf_before, hard_after - hard_before);
    
    hak_shutdown();
}

void test_system() {
    unsigned long pf_before, pf_after, hard_before, hard_after;
    
    printf("\n=== system malloc Test ===\n");
    
    get_pf(&pf_before, &hard_before);
    
    for (int i = 0; i < 10; i++) {
        void* buf = malloc(SIZE);
        memset(buf, 0xEF, SIZE);
        free(buf);
    }
    
    get_pf(&pf_after, &hard_after);
    
    printf("Page Faults: %lu (soft), %lu (hard)\n",
           pf_after - pf_before, hard_after - hard_before);
}

int main() {
    printf("=== Page Fault Comparison ===\n");
    printf("Size: 2MB × 10 iterations\n");
    
    test_system();
    test_hakmem();
    
    return 0;
}