1 #include <errno.h>
2 #include <fcntl.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <string.h>
6 #include <sys/mman.h>
7 #include <sys/time.h>
8
9 #include "pagingtest.h"
10
11 #define LINESIZE 32
12
thrashing_test(int test_runs)13 int thrashing_test(int test_runs) {
14 int fds[4] = {-1, -1, -1, -1};
15 char tmpnames[4][17] = { "thrashing1XXXXXX", "thrashing2XXXXXX", "thrashing3XXXXXX", "thrashing4XXXXXX" };
16 volatile char *bufs[4] = {0};
17 long long k;
18 int ret = -1;
19 struct timeval begin_time, end_time, elapsed_time, total_time;
20 unsigned long long filesize;
21 long num_pages;
22 long pagesize;
23
24 timerclear(&total_time);
25
26 num_pages = sysconf(_SC_PHYS_PAGES);
27 pagesize = sysconf(_SC_PAGE_SIZE);
28 if (num_pages < 0) {
29 fprintf(stderr, "failed to get the number of pages\n");
30 return -1;
31 }
32
33 filesize = num_pages * pagesize / (ARRAY_SIZE(fds) - 1);
34
35 for (size_t i = 0; i < ARRAY_SIZE(fds); i++) {
36 fds[i] = create_tmp_file(tmpnames[i], filesize);
37 if (fds[i] < 0) {
38 goto err_fd;
39 }
40 }
41
42 for (size_t i = 0; i < ARRAY_SIZE(fds); i++) {
43 bufs[i] = mmap(NULL, filesize, PROT_READ, MAP_PRIVATE, fds[i], 0);
44 if (bufs[i] == ((void *)-1)) {
45 fprintf(stderr, "Failed to mmap file: %s\n", strerror(errno));
46 goto err;
47 }
48 }
49
50 for (int i = 0; i < test_runs; i++) {
51 for (size_t j = 0; j < ARRAY_SIZE(fds); j++) {
52 gettimeofday(&begin_time, NULL);
53 //Unfortunately when under memory pressure, fadvise and madvise stop working...
54 //Read backwards to prevent mmap prefetching
55 for (k = ((filesize - 1) & ~(pagesize - 1)); k >= 0; k -= pagesize) {
56 bufs[j][k];
57 }
58 gettimeofday(&end_time, NULL);
59
60 timersub(&end_time, &begin_time, &elapsed_time);
61 timeradd(&total_time, &elapsed_time, &total_time);
62 }
63 }
64
65 printf("thrashing: %llu MB/s\n", (filesize * ARRAY_SIZE(fds) * test_runs * USEC_PER_SEC) /
66 (1024 * 1024 * (total_time.tv_sec * USEC_PER_SEC + total_time.tv_usec)));
67
68 ret = 0;
69
70 err:
71 for (size_t i = 0; i < ARRAY_SIZE(bufs) && bufs[i] != NULL; i++) {
72 munmap((void *)bufs[i], filesize);
73 }
74 err_fd:
75 for (size_t i = 0; i < ARRAY_SIZE(fds) && fds[i] >= 0; i++) {
76 close(fds[i]);
77 }
78 return ret;
79 }
80