[lttng-ust.git] / libringbuffer / smp.h

#ifndef _LIBRINGBUFFER_SMP_H
#define _LIBRINGBUFFER_SMP_H

/*
 * libringbuffer/smp.h
 *
 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "getcpu.h"

/*
 * 4kB of per-cpu data available. Enough to hold the control structures,
 * but not ring buffers.
 */
#define PER_CPU_MEM_SIZE	4096

extern int __num_possible_cpus;

#define LTTNG_UST_CPUMASK_SIZE 4096

/*
 * Get the CPU possible mask string from sysfs.
 *
 * buf: the buffer where the mask will be read.
 * max_bytes: the maximum number of bytes to write in the buffer.
 *
 * Returns the number of bytes read or -1 on error.
 */
int get_possible_cpu_mask_from_sysfs(char *buf, size_t max_bytes)
	__attribute__((visibility("hidden")));

/*
 * Get the number of possible CPUs in the system from either
 * sysconf(_SC_NPROCESSORS_CONF) or some other mechanism depending on the libc.
 *
 * Returns the number of possible CPUs in the system or 0 on error.
 */
int get_num_possible_cpus_fallback(void)
	__attribute__((visibility("hidden")));

/*
 * Get the number of CPUs from the possible cpu mask.
 *
 * pmask: the mask to parse.
 * len: the len of the mask excluding '\0'.
 *
 * Returns the number of possible CPUs from the mask or 0 on error.
 */
int get_num_possible_cpus_from_mask(const char *pmask, size_t len)
	__attribute__((visibility("hidden")));

extern void _get_num_possible_cpus(void);

/*
 * Returns the total number of CPUs in the system. If the cache is not yet
 * initialized, get the value from "/sys/devices/system/cpu/possible" or
 * fallback to sysconf and cache it.
 *
 * If all methods fail, don't populate the cache and return 0.
 */
static inline
int num_possible_cpus(void)
{
	if (caa_unlikely(!__num_possible_cpus))
		_get_num_possible_cpus();

	return __num_possible_cpus;
}

#define for_each_possible_cpu(cpu)		\
	for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)

#endif /* _LIBRINGBUFFER_SMP_H */
Commit	Line	Data
a6352fd4 MD	1	#ifndef _LIBRINGBUFFER_SMP_H
	2	#define _LIBRINGBUFFER_SMP_H
	3
	4	/*
	5	* libringbuffer/smp.h
	6	*
e92f3e28	7	* Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
a6352fd4	8	*
e92f3e28 MD	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
a6352fd4 MD	22	*/
a6352fd4 MD	23
2b2d6ff7	24	#include "getcpu.h"
a6352fd4 MD	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;
f1d40e23	33
bb6e798c MJ	34	#define LTTNG_UST_CPUMASK_SIZE 4096
bb6e798c MJ	35
f1d40e23 MJ	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
a6352fd4 MD	67	extern void _get_num_possible_cpus(void);
a6352fd4 MD	68
f1d40e23 MJ	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	*/
a6352fd4 MD	76	static inline
	77	int num_possible_cpus(void)
	78	{
f1d40e23	79	if (caa_unlikely(!__num_possible_cpus))
a6352fd4	80	_get_num_possible_cpus();
f1d40e23	81
a6352fd4 MD	82	return __num_possible_cpus;
	83	}
	84
a6352fd4 MD	85	#define for_each_possible_cpu(cpu) \
	86	for ((cpu) = 0; (cpu) < num_possible_cpus(); (cpu)++)
	87
	88	#endif /* _LIBRINGBUFFER_SMP_H */