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f13fb81ad3
There is no much gain in fallback to cpuinfo if sysfs is no present, usually on restricted environment neither will be present. It also simplifies the code and make all architecture use the sched_getaffinity as the sysfs fallback. Checked on sparc64-linux-gnu.
146 lines
4.0 KiB
C
146 lines
4.0 KiB
C
/* Determine various system internal values, Linux version.
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Copyright (C) 1996-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <dirent.h>
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#include <not-cancel.h>
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#include <scratch_buffer.h>
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#include <stdio.h>
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#include <stdio_ext.h>
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#include <sys/sysinfo.h>
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#include <sysdep.h>
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int
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__get_nprocs (void)
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{
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struct scratch_buffer set;
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scratch_buffer_init (&set);
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int r;
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while (true)
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{
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/* The possible error are EFAULT for an invalid buffer or ESRCH for
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invalid pid, none could happen. */
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r = INTERNAL_SYSCALL_CALL (sched_getaffinity, 0, set.length,
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set.data);
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if (r > 0)
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break;
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if (!scratch_buffer_grow (&set))
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/* Default to an SMP system in case we cannot obtain an accurate
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number. */
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return 2;
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}
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/* The scratch_buffer is aligned to max_align_t. */
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r = __sched_cpucount (r, (const cpu_set_t *) set.data);
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scratch_buffer_free (&set);
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return r;
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}
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libc_hidden_def (__get_nprocs)
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weak_alias (__get_nprocs, get_nprocs)
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/* On some architectures it is possible to distinguish between configured
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and active cpus. */
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int
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__get_nprocs_conf (void)
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{
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/* Try to use the sysfs filesystem. It has actual information about
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online processors. */
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DIR *dir = __opendir ("/sys/devices/system/cpu");
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if (dir != NULL)
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{
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int count = 0;
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struct dirent64 *d;
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while ((d = __readdir64 (dir)) != NULL)
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/* NB: the sysfs has d_type support. */
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if (d->d_type == DT_DIR && strncmp (d->d_name, "cpu", 3) == 0)
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{
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char *endp;
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unsigned long int nr = strtoul (d->d_name + 3, &endp, 10);
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if (nr != ULONG_MAX && endp != d->d_name + 3 && *endp == '\0')
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++count;
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}
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__closedir (dir);
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return count;
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}
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return 1;
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}
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libc_hidden_def (__get_nprocs_conf)
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weak_alias (__get_nprocs_conf, get_nprocs_conf)
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/* Compute (num*mem_unit)/pagesize, but avoid overflowing long int.
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In practice, mem_unit is never bigger than the page size, so after
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the first loop it is 1. [In the kernel, it is initialized to
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PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in
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kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can
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represent all the sizes measured in bytes]. */
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static long int
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sysinfo_mempages (unsigned long int num, unsigned int mem_unit)
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{
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unsigned long int ps = __getpagesize ();
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while (mem_unit > 1 && ps > 1)
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{
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mem_unit >>= 1;
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ps >>= 1;
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}
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num *= mem_unit;
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while (ps > 1)
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{
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ps >>= 1;
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num >>= 1;
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}
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return num;
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}
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/* Return the number of pages of total/available physical memory in
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the system. This used to be done by parsing /proc/meminfo, but
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that's unnecessarily expensive (and /proc is not always available).
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The sysinfo syscall provides the same information, and has been
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available at least since kernel 2.3.48. */
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long int
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__get_phys_pages (void)
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{
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struct sysinfo info;
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__sysinfo (&info);
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return sysinfo_mempages (info.totalram, info.mem_unit);
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}
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libc_hidden_def (__get_phys_pages)
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weak_alias (__get_phys_pages, get_phys_pages)
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long int
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__get_avphys_pages (void)
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{
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struct sysinfo info;
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__sysinfo (&info);
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return sysinfo_mempages (info.freeram, info.mem_unit);
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}
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libc_hidden_def (__get_avphys_pages)
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weak_alias (__get_avphys_pages, get_avphys_pages)
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