src/common/smp.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _UST_COMMON_SMP_H
   8 #define _UST_COMMON_SMP_H
   9
  10 /*
  11  * Get the CPU possible mask string from sysfs.
  12  *
  13  * buf: the buffer where the mask will be read.
  14  * max_bytes: the maximum number of bytes to write in the buffer.
  15  *
  16  * Returns the number of bytes read or -1 on error.
  17  */
  18 int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
  19         __attribute__((visibility("hidden")));
  20
  21 /*
  22  * Get the number of possible CPUs in the system from either
  23  * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc.
  24  *
  25  * Returns the number of possible CPUs in the system or 0 on error.
  26  */
  27 int get_num_possible_cpus_fallback(void)
  28         __attribute__((visibility("hidden")));
  29
  30 /*
  31  * Get the number of CPUs from the possible cpu mask.
  32  *
  33  * pmask: the mask to parse.
  34  * len: the len of the mask excluding '\0'.
  35  *
  36  * Returns the number of possible CPUs from the mask or 0 on error.
  37  */
  38 int get_num_possible_cpus_from_mask(const char *pmask, size_t len)
  39         __attribute__((visibility("hidden")));
  40
  41 /*
  42  * Returns the total number of CPUs in the system. If the cache is not yet
  43  * initialized, get the value from "/sys/devices/system/cpu/possible" or
  44  * fallback to sysconf and cache it.
  45  *
  46  * If all methods fail, don't populate the cache and return 0.
  47  */
  48 int num_possible_cpus(void)
  49         __attribute__((visibility("hidden")));
  50
  51 #define for_each_possible_cpu(cpu)              \
  52         for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)
  53
  54 #endif /* _UST_COMMON_SMP_H */