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#ifndef _LTTNG_GETCPU_H
#define _LTTNG_GETCPU_H
/*
* Copyright (c) 2011 - 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 <urcu/compiler.h>
#include <urcu/system.h>
#include <urcu/arch.h>
#include <config.h>
void lttng_ust_getcpu_init(void);
extern int (*lttng_get_cpu)(void);
#ifdef LTTNG_UST_DEBUG_VALGRIND
/*
* Fallback on cpu 0 if liblttng-ust is build with Valgrind support.
* get_cpu() returns the current CPU number. It may change due to
* migration, so it is only statistically accurate.
*/
static inline
int lttng_ust_get_cpu_internal(void)
{
return 0;
}
#else
/*
* sched_getcpu.
*/
#ifdef __linux__
#if !HAVE_SCHED_GETCPU
#include <sys/syscall.h>
#define __getcpu(cpu, node, cache) syscall(__NR_getcpu, cpu, node, cache)
/*
* If getcpu is not implemented in the kernel, use cpu 0 as fallback.
*/
static inline
int lttng_ust_get_cpu_internal(void)
{
int cpu, ret;
ret = __getcpu(&cpu, NULL, NULL);
if (caa_unlikely(ret < 0))
return 0;
return cpu;
}
#else /* HAVE_SCHED_GETCPU */
#include <sched.h>
/*
* If getcpu is not implemented in the kernel, use cpu 0 as fallback.
*/
static inline
int lttng_ust_get_cpu_internal(void)
{
int cpu;
cpu = sched_getcpu();
if (caa_unlikely(cpu < 0))
return 0;
return cpu;
}
#endif /* HAVE_SCHED_GETCPU */
#elif (defined(__FreeBSD__) || defined(__CYGWIN__))
/*
* FreeBSD and Cygwin do not allow query of CPU ID. Always use CPU
* number 0, with the assocated performance degradation on SMP.
*/
static inline
int lttng_ust_get_cpu_internal(void)
{
return 0;
}
#else
#error "Please add support for your OS into liblttng-ust/compat.h."
#endif
#endif
static inline
int lttng_ust_get_cpu(void)
{
int (*getcpu)(void) = CMM_LOAD_SHARED(lttng_get_cpu);
if (caa_likely(!getcpu)) {
return lttng_ust_get_cpu_internal();
} else {
return getcpu();
}
}
#endif /* _LTTNG_GETCPU_H */
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