1 /* Determine various system internal values, Linux version.
2 Copyright (C) 1996-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
29 #include <stdio_ext.h>
33 #include <sys/sysinfo.h>
36 #include <not-cancel.h>
39 /* How we can determine the number of available processors depends on
40 the configuration. There is currently (as of version 2.0.21) no
41 system call to determine the number. It is planned for the 2.1.x
42 series to add this, though.
44 One possibility to implement it for systems using Linux 2.0 is to
45 examine the pseudo file /proc/cpuinfo. Here we have one entry for
48 But not all systems have support for the /proc filesystem. If it
49 is not available we simply return 1 since there is no way. */
52 /* Other architectures use different formats for /proc/cpuinfo. This
53 provides a hook for alternative parsers. */
54 #ifndef GET_NPROCS_PARSER
55 # define GET_NPROCS_PARSER(FD, BUFFER, CP, RE, BUFFER_END, RESULT) \
59 /* Read all lines and count the lines starting with the string \
60 "processor". We don't have to fear extremely long lines since \
61 the kernel will not generate them. 8192 bytes are really \
64 while ((l = next_line (FD, BUFFER, &CP, &RE, BUFFER_END)) != NULL) \
65 if (strncmp (l, "processor", 9) == 0) \
73 next_line (int fd
, char *const buffer
, char **cp
, char **re
,
74 char *const buffer_end
)
77 char *nl
= memchr (*cp
, '\n', *re
- *cp
);
82 if (*re
== buffer_end
)
84 memmove (buffer
, *cp
, *re
- *cp
);
85 *re
= buffer
+ (*re
- *cp
);
88 ssize_t n
= __read_nocancel (fd
, *re
, buffer_end
- *re
);
94 nl
= memchr (*cp
, '\n', *re
- *cp
);
95 while (nl
== NULL
&& *re
== buffer_end
)
97 /* Truncate too long lines. */
98 *re
= buffer
+ 3 * (buffer_end
- buffer
) / 4;
99 n
= __read_nocancel (fd
, *re
, buffer_end
- *re
);
103 nl
= memchr (*re
, '\n', n
);
109 nl
= memchr (*cp
, '\n', *re
- *cp
);
121 return res
== *re
? NULL
: res
;
128 static int cached_result
= -1;
129 static time_t timestamp
;
131 time_t now
= time_now ();
132 time_t prev
= timestamp
;
133 atomic_read_barrier ();
134 if (now
== prev
&& cached_result
> -1)
135 return cached_result
;
137 /* XXX Here will come a test for the new system call. */
139 const size_t buffer_size
= __libc_use_alloca (8192) ? 8192 : 512;
140 char *buffer
= alloca (buffer_size
);
141 char *buffer_end
= buffer
+ buffer_size
;
142 char *cp
= buffer_end
;
143 char *re
= buffer_end
;
145 const int flags
= O_RDONLY
| O_CLOEXEC
;
146 int fd
= __open_nocancel ("/sys/devices/system/cpu/online", flags
);
151 l
= next_line (fd
, buffer
, &cp
, &re
, buffer_end
);
156 unsigned long int n
= strtoul (l
, &endp
, 10);
163 unsigned long int m
= n
;
167 m
= strtoul (l
, &endp
, 10);
178 while (l
< re
&& isspace (*l
))
183 __close_nocancel_nostatus (fd
);
192 /* Default to an SMP system in case we cannot obtain an accurate
196 /* The /proc/stat format is more uniform, use it by default. */
197 fd
= __open_nocancel ("/proc/stat", flags
);
202 while ((l
= next_line (fd
, buffer
, &cp
, &re
, buffer_end
)) != NULL
)
203 /* The current format of /proc/stat has all the cpu* entries
204 at the front. We assume here that stays this way. */
205 if (strncmp (l
, "cpu", 3) != 0)
207 else if (isdigit (l
[3]))
210 __close_nocancel_nostatus (fd
);
214 fd
= __open_nocancel ("/proc/cpuinfo", flags
);
217 GET_NPROCS_PARSER (fd
, buffer
, cp
, re
, buffer_end
, result
);
218 __close_nocancel_nostatus (fd
);
223 cached_result
= result
;
224 atomic_write_barrier ();
229 libc_hidden_def (__get_nprocs
)
230 weak_alias (__get_nprocs
, get_nprocs
)
233 /* On some architectures it is possible to distinguish between configured
236 __get_nprocs_conf (void)
238 /* XXX Here will come a test for the new system call. */
240 /* Try to use the sysfs filesystem. It has actual information about
241 online processors. */
242 DIR *dir
= __opendir ("/sys/devices/system/cpu");
248 while ((d
= __readdir64 (dir
)) != NULL
)
249 /* NB: the sysfs has d_type support. */
250 if (d
->d_type
== DT_DIR
&& strncmp (d
->d_name
, "cpu", 3) == 0)
253 unsigned long int nr
= strtoul (d
->d_name
+ 3, &endp
, 10);
254 if (nr
!= ULONG_MAX
&& endp
!= d
->d_name
+ 3 && *endp
== '\0')
265 #ifdef GET_NPROCS_CONF_PARSER
266 /* If we haven't found an appropriate entry return 1. */
267 FILE *fp
= fopen ("/proc/cpuinfo", "rce");
272 /* No threads use this stream. */
273 __fsetlocking (fp
, FSETLOCKING_BYCALLER
);
274 GET_NPROCS_CONF_PARSER (fp
, buffer
, result
);
278 result
= __get_nprocs ();
283 libc_hidden_def (__get_nprocs_conf
)
284 weak_alias (__get_nprocs_conf
, get_nprocs_conf
)
287 /* Compute (num*mem_unit)/pagesize, but avoid overflowing long int.
288 In practice, mem_unit is never bigger than the page size, so after
289 the first loop it is 1. [In the kernel, it is initialized to
290 PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in
291 kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can
292 represent all the sizes measured in bytes]. */
294 sysinfo_mempages (unsigned long int num
, unsigned int mem_unit
)
296 unsigned long int ps
= __getpagesize ();
298 while (mem_unit
> 1 && ps
> 1)
312 /* Return the number of pages of total/available physical memory in
313 the system. This used to be done by parsing /proc/meminfo, but
314 that's unnecessarily expensive (and /proc is not always available).
315 The sysinfo syscall provides the same information, and has been
316 available at least since kernel 2.3.48. */
318 __get_phys_pages (void)
323 return sysinfo_mempages (info
.totalram
, info
.mem_unit
);
325 libc_hidden_def (__get_phys_pages
)
326 weak_alias (__get_phys_pages
, get_phys_pages
)
329 __get_avphys_pages (void)
334 return sysinfo_mempages (info
.freeram
, info
.mem_unit
);
336 libc_hidden_def (__get_avphys_pages
)
337 weak_alias (__get_avphys_pages
, get_avphys_pages
)