1 #ifndef _LIBRINGBUFFER_SMP_H
2 #define _LIBRINGBUFFER_SMP_H
7 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
27 * 4kB of per-cpu data available. Enough to hold the control structures,
28 * but not ring buffers.
30 #define PER_CPU_MEM_SIZE 4096
32 extern int __num_possible_cpus
;
35 * Get the CPU possible mask string from sysfs.
37 * buf: the buffer where the mask will be read.
38 * max_bytes: the maximum number of bytes to write in the buffer.
40 * Returns the number of bytes read or -1 on error.
42 int get_possible_cpu_mask_from_sysfs(char *buf
, size_t max_bytes
)
43 __attribute__((visibility("hidden")));
46 * Get the number of possible CPUs in the system from either
47 * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc.
49 * Returns the number of possible CPUs in the system or 0 on error.
51 int get_num_possible_cpus_fallback(void)
52 __attribute__((visibility("hidden")));
55 * Get the number of CPUs from the possible cpu mask.
57 * pmask: the mask to parse.
58 * len: the len of the mask excluding '\0'.
60 * Returns the number of possible CPUs from the mask or 0 on error.
62 int get_num_possible_cpus_from_mask(const char *pmask
, size_t len
)
63 __attribute__((visibility("hidden")));
65 extern void _get_num_possible_cpus(void);
68 * Returns the total number of CPUs in the system. If the cache is not yet
69 * initialized, get the value from "/sys/devices/system/cpu/possible" or
70 * fallback to sysconf and cache it.
72 * If all methods fail, don't populate the cache and return 0.
75 int num_possible_cpus(void)
77 if (caa_unlikely(!__num_possible_cpus
))
78 _get_num_possible_cpus();
80 return __num_possible_cpus
;
83 #define for_each_possible_cpu(cpu) \
84 for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)
86 #endif /* _LIBRINGBUFFER_SMP_H */
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