#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define CHUNK (16UL * 1024 * 1024)   /* 16MB chunks */
#define NCHUNK 320                    /* ~5GB total, forces swap on 4GB box */

int main(void) {
    char *p[NCHUNK];
    for (unsigned long i = 0; i < NCHUNK; i++) {
        p[i] = malloc(CHUNK);
        if (!p[i]) { fprintf(stderr, "oom at %lu\n", i); break; }
        memset(p[i], (int)(i & 0xff), CHUNK);
        if ((i & 15) == 0) { fprintf(stderr, "touched %lu MB\n", (i+1) * 16); usleep(20000); }
    }
    /* keep it resident-ish busy then exit */
    sleep(2);
    return 0;
}