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glibc/sysdeps/unix/sysv/linux/getsysstats.c
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/* Determine various system internal values, Linux version. | |
Copyright (C) 1996-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <alloca.h> | |
#include <assert.h> | |
#include <ctype.h> | |
#include <dirent.h> | |
#include <errno.h> | |
#include <fcntl.h> | |
#include <mntent.h> | |
#include <paths.h> | |
#include <stdio.h> | |
#include <stdio_ext.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <unistd.h> | |
#include <sys/sysinfo.h> | |
#include <atomic.h> | |
#include <not-cancel.h> | |
/* How we can determine the number of available processors depends on | |
the configuration. There is currently (as of version 2.0.21) no | |
system call to determine the number. It is planned for the 2.1.x | |
series to add this, though. | |
One possibility to implement it for systems using Linux 2.0 is to | |
examine the pseudo file /proc/cpuinfo. Here we have one entry for | |
each processor. | |
But not all systems have support for the /proc filesystem. If it | |
is not available we simply return 1 since there is no way. */ | |
/* Other architectures use different formats for /proc/cpuinfo. This | |
provides a hook for alternative parsers. */ | |
#ifndef GET_NPROCS_PARSER | |
# define GET_NPROCS_PARSER(FD, BUFFER, CP, RE, BUFFER_END, RESULT) \ | |
do \ | |
{ \ | |
(RESULT) = 0; \ | |
/* Read all lines and count the lines starting with the string \ | |
"processor". We don't have to fear extremely long lines since \ | |
the kernel will not generate them. 8192 bytes are really \ | |
enough. */ \ | |
char *l; \ | |
while ((l = next_line (FD, BUFFER, &CP, &RE, BUFFER_END)) != NULL) \ | |
if (strncmp (l, "processor", 9) == 0) \ | |
++(RESULT); \ | |
} \ | |
while (0) | |
#endif | |
static char * | |
next_line (int fd, char *const buffer, char **cp, char **re, | |
char *const buffer_end) | |
{ | |
char *res = *cp; | |
char *nl = memchr (*cp, '\n', *re - *cp); | |
if (nl == NULL) | |
{ | |
if (*cp != buffer) | |
{ | |
if (*re == buffer_end) | |
{ | |
memmove (buffer, *cp, *re - *cp); | |
*re = buffer + (*re - *cp); | |
*cp = buffer; | |
ssize_t n = read_not_cancel (fd, *re, buffer_end - *re); | |
if (n < 0) | |
return NULL; | |
*re += n; | |
nl = memchr (*cp, '\n', *re - *cp); | |
while (nl == NULL && *re == buffer_end) | |
{ | |
/* Truncate too long lines. */ | |
*re = buffer + 3 * (buffer_end - buffer) / 4; | |
n = read_not_cancel (fd, *re, buffer_end - *re); | |
if (n < 0) | |
return NULL; | |
nl = memchr (*re, '\n', n); | |
**re = '\n'; | |
*re += n; | |
} | |
} | |
else | |
nl = memchr (*cp, '\n', *re - *cp); | |
res = *cp; | |
} | |
if (nl == NULL) | |
nl = *re - 1; | |
} | |
*cp = nl + 1; | |
assert (*cp <= *re); | |
return res == *re ? NULL : res; | |
} | |
int | |
__get_nprocs (void) | |
{ | |
static int cached_result = -1; | |
static time_t timestamp; | |
time_t now = time (NULL); | |
time_t prev = timestamp; | |
atomic_read_barrier (); | |
if (now == prev && cached_result > -1) | |
return cached_result; | |
/* XXX Here will come a test for the new system call. */ | |
const size_t buffer_size = __libc_use_alloca (8192) ? 8192 : 512; | |
char *buffer = alloca (buffer_size); | |
char *buffer_end = buffer + buffer_size; | |
char *cp = buffer_end; | |
char *re = buffer_end; | |
const int flags = O_RDONLY | O_CLOEXEC; | |
int fd = open_not_cancel_2 ("/sys/devices/system/cpu/online", flags); | |
char *l; | |
int result = 0; | |
if (fd != -1) | |
{ | |
l = next_line (fd, buffer, &cp, &re, buffer_end); | |
if (l != NULL) | |
do | |
{ | |
char *endp; | |
unsigned long int n = strtoul (l, &endp, 10); | |
if (l == endp) | |
{ | |
result = 0; | |
break; | |
} | |
unsigned long int m = n; | |
if (*endp == '-') | |
{ | |
l = endp + 1; | |
m = strtoul (l, &endp, 10); | |
if (l == endp) | |
{ | |
result = 0; | |
break; | |
} | |
} | |
result += m - n + 1; | |
l = endp; | |
while (l < re && isspace (*l)) | |
++l; | |
} | |
while (l < re); | |
close_not_cancel_no_status (fd); | |
if (result > 0) | |
goto out; | |
} | |
cp = buffer_end; | |
re = buffer_end; | |
result = 1; | |
/* The /proc/stat format is more uniform, use it by default. */ | |
fd = open_not_cancel_2 ("/proc/stat", flags); | |
if (fd != -1) | |
{ | |
result = 0; | |
while ((l = next_line (fd, buffer, &cp, &re, buffer_end)) != NULL) | |
/* The current format of /proc/stat has all the cpu* entries | |
at the front. We assume here that stays this way. */ | |
if (strncmp (l, "cpu", 3) != 0) | |
break; | |
else if (isdigit (l[3])) | |
++result; | |
close_not_cancel_no_status (fd); | |
} | |
else | |
{ | |
fd = open_not_cancel_2 ("/proc/cpuinfo", flags); | |
if (fd != -1) | |
{ | |
GET_NPROCS_PARSER (fd, buffer, cp, re, buffer_end, result); | |
close_not_cancel_no_status (fd); | |
} | |
} | |
out: | |
cached_result = result; | |
atomic_write_barrier (); | |
timestamp = now; | |
return result; | |
} | |
weak_alias (__get_nprocs, get_nprocs) | |
/* On some architectures it is possible to distinguish between configured | |
and active cpus. */ | |
int | |
__get_nprocs_conf (void) | |
{ | |
/* XXX Here will come a test for the new system call. */ | |
/* Try to use the sysfs filesystem. It has actual information about | |
online processors. */ | |
DIR *dir = __opendir ("/sys/devices/system/cpu"); | |
if (dir != NULL) | |
{ | |
int count = 0; | |
struct dirent64 *d; | |
while ((d = __readdir64 (dir)) != NULL) | |
/* NB: the sysfs has d_type support. */ | |
if (d->d_type == DT_DIR && strncmp (d->d_name, "cpu", 3) == 0) | |
{ | |
char *endp; | |
unsigned long int nr = strtoul (d->d_name + 3, &endp, 10); | |
if (nr != ULONG_MAX && endp != d->d_name + 3 && *endp == '\0') | |
++count; | |
} | |
__closedir (dir); | |
return count; | |
} | |
int result = 1; | |
#ifdef GET_NPROCS_CONF_PARSER | |
/* If we haven't found an appropriate entry return 1. */ | |
FILE *fp = fopen ("/proc/cpuinfo", "rce"); | |
if (fp != NULL) | |
{ | |
char buffer[8192]; | |
/* No threads use this stream. */ | |
__fsetlocking (fp, FSETLOCKING_BYCALLER); | |
GET_NPROCS_CONF_PARSER (fp, buffer, result); | |
fclose (fp); | |
} | |
#else | |
result = __get_nprocs (); | |
#endif | |
return result; | |
} | |
weak_alias (__get_nprocs_conf, get_nprocs_conf) | |
/* Compute (num*mem_unit)/pagesize, but avoid overflowing long int. | |
In practice, mem_unit is never bigger than the page size, so after | |
the first loop it is 1. [In the kernel, it is initialized to | |
PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in | |
kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can | |
represent all the sizes measured in bytes]. */ | |
static long int | |
sysinfo_mempages (unsigned long int num, unsigned int mem_unit) | |
{ | |
unsigned long int ps = __getpagesize (); | |
while (mem_unit > 1 && ps > 1) | |
{ | |
mem_unit >>= 1; | |
ps >>= 1; | |
} | |
num *= mem_unit; | |
while (ps > 1) | |
{ | |
ps >>= 1; | |
num >>= 1; | |
} | |
return num; | |
} | |
/* Return the number of pages of total/available physical memory in | |
the system. This used to be done by parsing /proc/meminfo, but | |
that's unnecessarily expensive (and /proc is not always available). | |
The sysinfo syscall provides the same information, and has been | |
available at least since kernel 2.3.48. */ | |
long int | |
__get_phys_pages (void) | |
{ | |
struct sysinfo info; | |
__sysinfo (&info); | |
return sysinfo_mempages (info.totalram, info.mem_unit); | |
} | |
weak_alias (__get_phys_pages, get_phys_pages) | |
long int | |
__get_avphys_pages (void) | |
{ | |
struct sysinfo info; | |
__sysinfo (&info); | |
return sysinfo_mempages (info.freeram, info.mem_unit); | |
} | |
weak_alias (__get_avphys_pages, get_avphys_pages) |