1#include <errno.h>
2#include <fcntl.h>
3#include <stdbool.h>
4#include <stdio.h>
5#include <stdlib.h>
6#include <string.h>
7#include <sys/mman.h>
8#include <sys/time.h>
9
10#include "pagingtest.h"
11
12#define LINESIZE 32
13
14int thrashing_test(int test_runs, bool cache) {
15    int fds[4] = {-1, -1, -1, -1};
16    char tmpnames[4][17] = { "thrashing1XXXXXX", "thrashing2XXXXXX", "thrashing3XXXXXX", "thrashing4XXXXXX" };
17    volatile char *bufs[4] = {0};
18    unsigned long long k;
19    int ret = -1;
20    struct timeval begin_time, end_time, elapsed_time, total_time;
21    unsigned long long filesize;
22    long num_pages;
23    long pagesize;
24
25    timerclear(&total_time);
26
27    num_pages = sysconf(_SC_PHYS_PAGES);
28    pagesize = sysconf(_SC_PAGE_SIZE);
29    if (num_pages < 0) {
30        fprintf(stderr, "failed to get the number of pages\n");
31        return -1;
32    }
33
34    filesize = num_pages * pagesize / (ARRAY_SIZE(fds) - 1);
35
36    for (size_t i = 0; i < ARRAY_SIZE(fds); i++) {
37        fds[i] = create_tmp_file(tmpnames[i], filesize);
38        if (fds[i] < 0) {
39            goto err_fd;
40        }
41    }
42
43    for (size_t i = 0; i < ARRAY_SIZE(fds); i++) {
44        bufs[i] = mmap(NULL, filesize, PROT_READ, MAP_PRIVATE, fds[i], 0);
45        if (bufs[i] == ((void *)-1)) {
46            fprintf(stderr, "Failed to mmap file: %s\n", strerror(errno));
47            goto err;
48        }
49        if (!cache) {
50            //madvise and fadvise as random to prevent prefetching
51            ret = madvise((void *)bufs[i], filesize, MADV_RANDOM) ||
52                    posix_fadvise(fds[i], 0, filesize, POSIX_FADV_RANDOM);
53            if (ret) {
54                goto err;
55            }
56        }
57    }
58
59    for (int i = 0; i < test_runs; i++) {
60        for (size_t j = 0; j < ARRAY_SIZE(fds); j++) {
61            gettimeofday(&begin_time, NULL);
62            for (k = 0; k < filesize; k += pagesize) {
63                bufs[j][k];
64            }
65            gettimeofday(&end_time, NULL);
66
67            timersub(&end_time, &begin_time, &elapsed_time);
68            timeradd(&total_time, &elapsed_time, &total_time);
69        }
70    }
71
72    printf("%scached thrashing: %llu MB/s\n", cache ? "" : "un",
73             (filesize * ARRAY_SIZE(fds) * test_runs * USEC_PER_SEC) /
74             (1024 * 1024 * (total_time.tv_sec * USEC_PER_SEC + total_time.tv_usec)));
75
76    ret = 0;
77
78err:
79    for (size_t i = 0; i < ARRAY_SIZE(bufs) && bufs[i] != NULL; i++) {
80        munmap((void *)bufs[i], filesize);
81    }
82err_fd:
83    for (size_t i = 0; i < ARRAY_SIZE(fds) && fds[i] >= 0; i++) {
84        close(fds[i]);
85    }
86    return ret;
87}
88