| 1 | #ifndef _LIBRINGBUFFER_SMP_H |
| 2 | #define _LIBRINGBUFFER_SMP_H |
| 3 | |
| 4 | /* |
| 5 | * libringbuffer/smp.h |
| 6 | * |
| 7 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU Lesser General Public |
| 11 | * License as published by the Free Software Foundation; only |
| 12 | * version 2.1 of the License. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 17 | * Lesser General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 22 | */ |
| 23 | |
| 24 | #include "getcpu.h" |
| 25 | |
| 26 | /* |
| 27 | * 4kB of per-cpu data available. Enough to hold the control structures, |
| 28 | * but not ring buffers. |
| 29 | */ |
| 30 | #define PER_CPU_MEM_SIZE 4096 |
| 31 | |
| 32 | extern int __num_possible_cpus; |
| 33 | |
| 34 | #define LTTNG_UST_CPUMASK_SIZE 4096 |
| 35 | |
| 36 | /* |
| 37 | * Get the CPU possible mask string from sysfs. |
| 38 | * |
| 39 | * buf: the buffer where the mask will be read. |
| 40 | * max_bytes: the maximum number of bytes to write in the buffer. |
| 41 | * |
| 42 | * Returns the number of bytes read or -1 on error. |
| 43 | */ |
| 44 | int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes) |
| 45 | __attribute__((visibility("hidden"))); |
| 46 | |
| 47 | /* |
| 48 | * Get the number of possible CPUs in the system from either |
| 49 | * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc. |
| 50 | * |
| 51 | * Returns the number of possible CPUs in the system or 0 on error. |
| 52 | */ |
| 53 | int get_num_possible_cpus_fallback(void) |
| 54 | __attribute__((visibility("hidden"))); |
| 55 | |
| 56 | /* |
| 57 | * Get the number of CPUs from the possible cpu mask. |
| 58 | * |
| 59 | * pmask: the mask to parse. |
| 60 | * len: the len of the mask excluding '\0'. |
| 61 | * |
| 62 | * Returns the number of possible CPUs from the mask or 0 on error. |
| 63 | */ |
| 64 | int get_num_possible_cpus_from_mask(const char *pmask, size_t len) |
| 65 | __attribute__((visibility("hidden"))); |
| 66 | |
| 67 | extern void _get_num_possible_cpus(void); |
| 68 | |
| 69 | /* |
| 70 | * Returns the total number of CPUs in the system. If the cache is not yet |
| 71 | * initialized, get the value from "/sys/devices/system/cpu/possible" or |
| 72 | * fallback to sysconf and cache it. |
| 73 | * |
| 74 | * If all methods fail, don't populate the cache and return 0. |
| 75 | */ |
| 76 | static inline |
| 77 | int num_possible_cpus(void) |
| 78 | { |
| 79 | if (caa_unlikely(!__num_possible_cpus)) |
| 80 | _get_num_possible_cpus(); |
| 81 | |
| 82 | return __num_possible_cpus; |
| 83 | } |
| 84 | |
| 85 | #define for_each_possible_cpu(cpu) \ |
| 86 | for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++) |
| 87 | |
| 88 | #endif /* _LIBRINGBUFFER_SMP_H */ |