1 #include <errno.h>
2 #include <fcntl.h>
3 #include <getopt.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <sys/mman.h>
8 #include <sys/wait.h>
9 #include <unistd.h>
10
alloc_set(size_t size)11 void* alloc_set(size_t size) {
12 void* addr = NULL;
13
14 addr = malloc(size);
15 if (!addr) {
16 printf("Allocating %zd MB failed\n", size / 1024 / 1024);
17 } else {
18 memset(addr, 0, size);
19 }
20 return addr;
21 }
22
add_pressure(size_t * shared,size_t size,size_t step_size,size_t duration,const char * oom_score)23 void add_pressure(size_t* shared, size_t size, size_t step_size, size_t duration,
24 const char* oom_score) {
25 int fd, ret;
26
27 fd = open("/proc/self/oom_score_adj", O_WRONLY);
28 ret = write(fd, oom_score, strlen(oom_score));
29 if (ret < 0) {
30 printf("Writing oom_score_adj failed with err %s\n", strerror(errno));
31 }
32 close(fd);
33
34 if (alloc_set(size)) {
35 *shared = size;
36 }
37
38 while (alloc_set(step_size)) {
39 size += step_size;
40 *shared = size;
41 usleep(duration);
42 }
43 }
44
usage()45 void usage() {
46 printf("Usage: [OPTIONS]\n\n"
47 " -d N: Duration in microsecond to sleep between each allocation.\n"
48 " -i N: Number of iterations to run the alloc process.\n"
49 " -o N: The oom_score to set the child process to before alloc.\n"
50 " -s N: Number of bytes to allocate in an alloc process loop.\n");
51 }
52
main(int argc,char * argv[])53 int main(int argc, char* argv[]) {
54 pid_t pid;
55 size_t* shared;
56 int c, i = 0;
57
58 size_t duration = 1000;
59 int iterations = 0;
60 const char* oom_score = "899";
61 size_t step_size = 2 * 1024 * 1024; // 2 MB
62 size_t size = step_size;
63
64 while ((c = getopt(argc, argv, "hi:d:o:s:")) != -1) {
65 switch (c) {
66 case 'i':
67 iterations = atoi(optarg);
68 break;
69 case 'd':
70 duration = atoi(optarg);
71 break;
72 case 'o':
73 oom_score = optarg;
74 break;
75 case 's':
76 step_size = atoi(optarg);
77 break;
78 case 'h':
79 usage();
80 abort();
81 default:
82 abort();
83 }
84 }
85
86 shared = (size_t*)mmap(NULL, sizeof(size_t), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED,
87 0, 0);
88
89 while (iterations == 0 || i < iterations) {
90 *shared = 0;
91 pid = fork();
92 if (!pid) {
93 /* Child */
94 add_pressure(shared, size, step_size, duration, oom_score);
95 /* Shoud not get here */
96 exit(0);
97 } else {
98 wait(NULL);
99 printf("Child %d allocated %zd MB\n", i, *shared / 1024 / 1024);
100 size = *shared / 2;
101 }
102 i++;
103 }
104 }
105