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
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <unistd.h>
#include "alloc-util.h"
#include "cgroup-util.h"
#include "limits-util.h"
#include "memory-util.h"
#include "parse-util.h"
#include "process-util.h"
#include "procfs-util.h"
#include "string-util.h"
uint64_t physical_memory(void) {
_cleanup_free_ char *root = NULL, *value = NULL;
uint64_t mem, lim;
size_t ps;
long sc;
int r;
/* We return this as uint64_t in case we are running as 32bit process on a 64bit kernel with huge amounts of
* memory.
*
* In order to support containers nicely that have a configured memory limit we'll take the minimum of the
* physically reported amount of memory and the limit configured for the root cgroup, if there is any. */
sc = sysconf(_SC_PHYS_PAGES);
assert(sc > 0);
ps = page_size();
mem = (uint64_t) sc * (uint64_t) ps;
r = cg_get_root_path(&root);
if (r < 0) {
log_debug_errno(r, "Failed to determine root cgroup, ignoring cgroup memory limit: %m");
return mem;
}
r = cg_all_unified();
if (r < 0) {
log_debug_errno(r, "Failed to determine root unified mode, ignoring cgroup memory limit: %m");
return mem;
}
if (r > 0) {
r = cg_get_attribute("memory", root, "memory.max", &value);
if (r == -ENOENT) /* Field does not exist on the system's top-level cgroup, hence don't
* complain. (Note that it might exist on our own root though, if we live
* in a cgroup namespace, hence check anyway instead of not even
* trying.) */
return mem;
if (r < 0) {
log_debug_errno(r, "Failed to read memory.max cgroup attribute, ignoring cgroup memory limit: %m");
return mem;
}
if (streq(value, "max"))
return mem;
} else {
r = cg_get_attribute("memory", root, "memory.limit_in_bytes", &value);
if (r < 0) {
log_debug_errno(r, "Failed to read memory.limit_in_bytes cgroup attribute, ignoring cgroup memory limit: %m");
return mem;
}
}
r = safe_atou64(value, &lim);
if (r < 0) {
log_debug_errno(r, "Failed to parse cgroup memory limit '%s', ignoring: %m", value);
return mem;
}
if (lim == UINT64_MAX)
return mem;
/* Make sure the limit is a multiple of our own page size */
lim /= ps;
lim *= ps;
return MIN(mem, lim);
}
uint64_t physical_memory_scale(uint64_t v, uint64_t max) {
uint64_t p, m, ps;
/* Shortcut two special cases */
if (v == 0)
return 0;
if (v == max)
return physical_memory();
assert(max > 0);
/* Returns the physical memory size, multiplied by v divided by max. Returns UINT64_MAX on overflow. On success
* the result is a multiple of the page size (rounds down). */
ps = page_size();
assert(ps > 0);
p = physical_memory() / ps;
assert(p > 0);
if (v > UINT64_MAX / p)
return UINT64_MAX;
m = p * v;
m /= max;
if (m > UINT64_MAX / ps)
return UINT64_MAX;
return m * ps;
}
uint64_t system_tasks_max(void) {
uint64_t a = TASKS_MAX, b = TASKS_MAX, c = TASKS_MAX;
_cleanup_free_ char *root = NULL;
int r;
/* Determine the maximum number of tasks that may run on this system. We check three sources to
* determine this limit:
*
* a) kernel.threads-max sysctl: the maximum number of tasks (threads) the kernel allows.
*
* This puts a direct limit on the number of concurrent tasks.
*
* b) kernel.pid_max sysctl: the maximum PID value.
*
* This limits the numeric range PIDs can take, and thus indirectly also limits the number of
* concurrent threads. It's primarily a compatibility concept: some crappy old code used a signed
* 16bit type for PIDs, hence the kernel provides a way to ensure the PIDs never go beyond
* INT16_MAX by default.
*
* Also note the weird definition: PIDs assigned will be kept below this value, which means
* the number of tasks that can be created is one lower, as PID 0 is not a valid process ID.
*
* c) pids.max on the root cgroup: the kernel's configured maximum number of tasks.
*
* and then pick the smallest of the three.
*
* By default pid_max is set to much lower values than threads-max, hence the limit people come into
* contact with first, as it's the lowest boundary they need to bump when they want higher number of
* processes.
*/
r = procfs_get_threads_max(&a);
if (r < 0)
log_debug_errno(r, "Failed to read kernel.threads-max, ignoring: %m");
r = procfs_get_pid_max(&b);
if (r < 0)
log_debug_errno(r, "Failed to read kernel.pid_max, ignoring: %m");
else if (b > 0)
/* Subtract one from pid_max, since PID 0 is not a valid PID */
b--;
r = cg_get_root_path(&root);
if (r < 0)
log_debug_errno(r, "Failed to determine cgroup root path, ignoring: %m");
else {
/* We'll have the "pids.max" attribute on the our root cgroup only if we are in a
* CLONE_NEWCGROUP namespace. On the top-level namespace this attribute is missing, hence
* suppress any message about that */
r = cg_get_attribute_as_uint64("pids", root, "pids.max", &c);
if (r < 0 && r != -ENODATA)
log_debug_errno(r, "Failed to read pids.max attribute of root cgroup, ignoring: %m");
}
return MIN3(a, b, c);
}
uint64_t system_tasks_max_scale(uint64_t v, uint64_t max) {
uint64_t t, m;
/* Shortcut two special cases */
if (v == 0)
return 0;
if (v == max)
return system_tasks_max();
assert(max > 0);
/* Multiply the system's task value by the fraction v/max. Hence, if max==100 this calculates percentages
* relative to the system's maximum number of tasks. Returns UINT64_MAX on overflow. */
t = system_tasks_max();
assert(t > 0);
if (v > UINT64_MAX / t) /* overflow? */
return UINT64_MAX;
m = t * v;
return m / max;
}
|
