1 /* Compile with: 2 * i686-pc-linux-gnu-gcc hog.c -o hog 3 */ 4 5 #include <fcntl.h> 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <string.h> 9 #include <unistd.h> 10 #include <sys/stat.h> 11 #include <sys/types.h> 12 13 #define MEGA (1 << 20) 14 #define CHUNK_SIZE MEGA /* one-megabyte chunks */ 15 #define MAX_CHUNKS 4096 16 const int n_touches = CHUNK_SIZE >> 12; /* average 1 per page */ 17 char *chunks[MAX_CHUNKS]; 18 19 20 long int estrtol(const char *s) { 21 char *end; 22 long int n; 23 n = strtol(s, &end, 10); 24 if (*end != '\0') { 25 fprintf(stderr, "hog: malformed integer %s\n", s); 26 exit(1); 27 } 28 return n; 29 } 30 31 32 int main(int ac, const char **av) { 33 int chunk; 34 int compression_factor = 3; 35 unsigned int i, c, x; 36 long int megabytes; 37 int random_fd = open("/dev/urandom", O_RDONLY); 38 char *fake_data = malloc(CHUNK_SIZE); 39 char *p; 40 41 if (ac != 2 && ac != 3) { 42 fprintf(stderr, 43 "usage: hog <megabytes> [<compression factor (default = 3)>]\n"); 44 exit(1); 45 } 46 47 megabytes = estrtol(av[1]); 48 49 if (megabytes > MAX_CHUNKS) { 50 fprintf(stderr, "hog: too many megabytes (%ld, max = %d)\n", 51 megabytes, MAX_CHUNKS); 52 } 53 54 if (ac == 3) { 55 compression_factor = estrtol(av[2]); 56 } 57 58 /* Fill fake_data with fake data so that it compresses to roughly the desired 59 * compression factor. 60 */ 61 read(random_fd, fake_data, CHUNK_SIZE / compression_factor); 62 /* Fill the rest of the fake data with ones (compresses well). */ 63 memset(fake_data + CHUNK_SIZE / compression_factor, 1, 64 CHUNK_SIZE - (CHUNK_SIZE / compression_factor)); 65 66 for (chunk = 0; chunk < megabytes; chunk++) { 67 /* Allocate */ 68 p = malloc(CHUNK_SIZE); 69 70 if (p == NULL) { 71 printf("hog: out of memory at chunk %d\n", chunk); 72 break; 73 } 74 75 /* Fill allocated memory with fake data */ 76 memcpy(p, fake_data, CHUNK_SIZE); 77 78 /* Remember allocated data. */ 79 chunks[chunk] = p; 80 } 81 82 printf("hog: idling\n", chunk); 83 while (1) 84 sleep(10); 85 } 86
