1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/sysinfo.h>
// 8 bytes page tables + 64 bytes mem map
// However may be mem_map (struct page) is already excluded?
#define BYTES_PER_PAGE 8
int main(int argc, char *argv[]) {
int err;
size_t size;
void *buf;
FILE *f;
struct sysinfo info;
if (argc < 2) {
printf("Usage: %s [+]<GB>\n", argv[0]);
printf(" + : lock this amount of memory\n");
printf(" = : total memory after lock\n");
printf(" - : free memory after lock [default]\n");
exit(0);
}
f = fopen("/proc/sys/vm/drop_caches", "w");
if (!f) {
printf("Failed to drop caches...\n");
exit(-1);
}
fprintf(f, "3\n");
fclose(f);
err = sysinfo(&info);
if (err) {
printf("sysinfo failed with errno: %i\n", errno);
exit(-1);
}
if ((argv[1][0] < '0')||(argv[1][0] > '9'))
size = atol(argv[1]+1) * 1024 * 1024 * 1024;
else
size = atol(argv[1]) * 1024 * 1024 * 1024;
if (argv[1][0]=='+') {
} else if (argv[1][0]=='=') {
size_t page_size = getpagesize();
size_t pages;
size_t page_tables;
pages = (info.totalram * info.mem_unit) / page_size;
page_tables = pages * BYTES_PER_PAGE;
printf("Detected %zu units of memory, unit size %u\n", info.totalram, info.mem_unit);
printf("Expected size of page tables: %zu MB, \n", page_tables / 1024 / 1024);
printf("Leaving aside %zu bytes\n", size);
if (info.totalram * info.mem_unit < size) {
printf("Requested more memory (%zu GB) when available (%zu GB)\n", size / 1024 / 1024 / 1024, info.totalram * info.mem_unit / 1024 / 1024 / 1024);
exit(-1);
}
size = info.totalram * info.mem_unit - size - page_tables;
} else {
if (info.freeram*info.mem_unit < size) {
printf("Requested more memory (%zu GB) when is currently free (%zu GB)\n", size / 1024 / 1024 / 1024, info.freeram * info.mem_unit / 1024 / 1024 / 1024);
exit(-1);
}
size = info.freeram * info.mem_unit - size;
}
if (!size) exit(0);
printf("Trying to get %zu bytes\n", size);
buf = malloc(size);
if (!buf) {
printf("Allocation failed\n");
exit(-1);
}
err = mlock(buf, size);
if (err) {
printf("Locking memory failed, errno: %i\n", errno);
exit(-1);
}
printf("Locked %zu GB memory\n", size/1024/1024/1024);
while (1) sleep(60);
}
|