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/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
* Copyright (c) 2020 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
*
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "opal_config.h"
#include <time.h>
#ifdef HAVE_SCHED_H
# include <sched.h>
#endif
#include "opal/constants.h"
#include "opal/mca/threads/pthreads/threads_pthreads.h"
#include "opal/mca/threads/thread.h"
static void opal_thread_pthreads_yield_sched_yield(void);
static void opal_thread_pthreads_yield_nanosleep(void);
typedef enum {
OPAL_PTHREADS_YIELD_SCHED_YIELD = 0,
OPAL_PTHREADS_YIELD_NANOSLEEP
} opal_threads_pthreads_yield_strategy_t;
static mca_base_var_enum_value_t yield_strategy_values[] = {{OPAL_PTHREADS_YIELD_SCHED_YIELD,
"sched_yield"},
{OPAL_PTHREADS_YIELD_NANOSLEEP,
"nanosleep"},
{0, NULL}};
/* Number of nanoseconds to nanosleep, if enabled */
static uint64_t yield_nsleep_nanosecs;
/* The time to nanosleep, if enabled */
static struct timespec yield_nsleep_time = {.tv_sec = 0, .tv_nsec = 1};
static opal_threads_pthreads_yield_strategy_t yield_strategy = OPAL_PTHREADS_YIELD_SCHED_YIELD;
opal_threads_pthreads_yield_fn_t *opal_threads_pthreads_yield_fn
= &opal_thread_pthreads_yield_sched_yield;
int opal_threads_pthreads_yield_init(const mca_base_component_t *component)
{
mca_base_var_enum_t *yield_strategy_enumerator;
mca_base_var_enum_create("pthread_yield_strategies", yield_strategy_values,
&yield_strategy_enumerator);
(void) mca_base_component_var_register(component, "yield_strategy",
"Pthread yield strategy to use", MCA_BASE_VAR_TYPE_INT,
yield_strategy_enumerator, 0, 0, OPAL_INFO_LVL_3,
MCA_BASE_VAR_SCOPE_LOCAL, &yield_strategy);
switch (yield_strategy) {
case OPAL_PTHREADS_YIELD_NANOSLEEP:
opal_threads_pthreads_yield_fn = &opal_thread_pthreads_yield_nanosleep;
break;
default:
/* use initial value */
break;
}
OBJ_RELEASE(yield_strategy_enumerator);
yield_nsleep_nanosecs = (yield_nsleep_time.tv_sec * 1E9) + yield_nsleep_time.tv_nsec;
(void) mca_base_component_var_register(
component, "nanosleep_time",
"Number of nanoseconds to sleep when using nanosleep as the pthread yield strategy",
MCA_BASE_VAR_TYPE_UINT64_T, NULL, 0, 0, OPAL_INFO_LVL_3, MCA_BASE_VAR_SCOPE_LOCAL,
&yield_nsleep_nanosecs);
yield_nsleep_time.tv_sec = yield_nsleep_nanosecs / 1E9;
yield_nsleep_time.tv_nsec = yield_nsleep_nanosecs - (uint64_t)(yield_nsleep_time.tv_sec * 1E9);
return OPAL_SUCCESS;
}
void opal_thread_pthreads_yield_sched_yield(void)
{
#ifdef HAVE_SCHED_H
sched_yield();
#endif
}
void opal_thread_pthreads_yield_nanosleep(void)
{
nanosleep(&yield_nsleep_time, NULL);
}
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