| 1 | /* |
| 2 | * libringbuffer/smp.c |
| 3 | * |
| 4 | * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * Dual LGPL v2.1/GPL v2 license. |
| 7 | */ |
| 8 | |
| 9 | #define _GNU_SOURCE |
| 10 | #include <unistd.h> |
| 11 | #include "usterr.h" |
| 12 | #include <pthread.h> |
| 13 | #include "smp.h" |
| 14 | |
| 15 | int __num_possible_cpus; |
| 16 | |
| 17 | void _get_num_possible_cpus(void) |
| 18 | { |
| 19 | int result; |
| 20 | |
| 21 | /* On Linux, when some processors are offline |
| 22 | * _SC_NPROCESSORS_CONF counts the offline |
| 23 | * processors, whereas _SC_NPROCESSORS_ONLN |
| 24 | * does not. If we used _SC_NPROCESSORS_ONLN, |
| 25 | * getcpu() could return a value greater than |
| 26 | * this sysconf, in which case the arrays |
| 27 | * indexed by processor would overflow. |
| 28 | */ |
| 29 | result = sysconf(_SC_NPROCESSORS_CONF); |
| 30 | if (result == -1) |
| 31 | return; |
| 32 | __num_possible_cpus = result; |
| 33 | } |