examples/performance-thread/pthread_shim/main.c

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2015 Intel Corporation
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <sys/types.h>
#include <string.h>
#include <sys/queue.h>
#include <stdarg.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h>
#include <sched.h>
#include <pthread.h>

#include <rte_common.h>
#include <rte_lcore.h>
#include <rte_per_lcore.h>
#include <rte_timer.h>

#include "lthread_api.h"
#include "lthread_diag_api.h"
#include "pthread_shim.h"

#define DEBUG_APP 0
#define HELLOW_WORLD_MAX_LTHREADS 10

#ifndef __GLIBC__ /* sched_getcpu() is glibc-specific */
#define sched_getcpu() rte_lcore_id()
#endif

__thread int print_count;
__thread pthread_mutex_t print_lock;

__thread pthread_mutex_t exit_lock;
__thread pthread_cond_t exit_cond;

/*
 * A simple thread that demonstrates use of a mutex, a condition
 * variable, thread local storage, explicit yield, and thread exit.
 *
 * The thread uses a mutex to protect a shared counter which is incremented
 * and then it waits on condition variable before exiting.
 *
 * The thread argument is stored in and retrieved from TLS, using
 * the pthread key create, get and set specific APIs.
 *
 * The thread yields while holding the mutex, to provide opportunity
 * for other threads to contend.
 *
 * All of the pthread API functions used by this thread are actually
 * resolved to corresponding lthread functions by the pthread shim
 * implemented in pthread_shim.c
 */
void *helloworld_pthread(void *arg);
void *helloworld_pthread(void *arg)
{
    pthread_key_t key;

    /* create a key for TLS */
    pthread_key_create(&key, NULL);

    /* store the arg in TLS */
    pthread_setspecific(key, arg);

    /* grab lock and increment shared counter */
    pthread_mutex_lock(&print_lock);
    print_count++;

    /* yield thread to give opportunity for lock contention */
    sched_yield();

    /* retrieve arg from TLS */
    uint64_t thread_no = (uint64_t) pthread_getspecific(key);

    printf("Hello - lcore = %d count = %d thread_no = %d thread_id = %p\n",
            sched_getcpu(),
            print_count,
            (int) thread_no,
            (void *)pthread_self());

    /* release the lock */
    pthread_mutex_unlock(&print_lock);

    /*
     * wait on condition variable
     * before exiting
     */
    pthread_mutex_lock(&exit_lock);
    pthread_cond_wait(&exit_cond, &exit_lock);
    pthread_mutex_unlock(&exit_lock);

    /* exit */
    pthread_exit((void *) thread_no);
}


/*
 * This is the initial thread
 *
 * It demonstrates pthread, mutex and condition variable creation,
 * broadcast and pthread join APIs.
 *
 * This initial thread must always start life as an lthread.
 *
 * This thread creates many more threads then waits a short time
 * before signalling them to exit using a broadcast.
 *
 * All of the pthread API functions used by this thread are actually
 * resolved to corresponding lthread functions by the pthread shim
 * implemented in pthread_shim.c
 *
 * After all threads have finished the lthread scheduler is shutdown
 * and normal pthread operation is restored
 */
__thread pthread_t tid[HELLOW_WORLD_MAX_LTHREADS];

static void *initial_lthread(void *args __attribute__((unused)))
{
    int lcore = (int) rte_lcore_id();
    /*
     *
     * We can now enable pthread API override
     * and start to use the pthread APIs
     */
    pthread_override_set(1);

    uint64_t i;
    int ret;

    /* initialize mutex for shared counter */
    print_count = 0;
    pthread_mutex_init(&print_lock, NULL);

    /* initialize mutex and condition variable controlling thread exit */
    pthread_mutex_init(&exit_lock, NULL);
    pthread_cond_init(&exit_cond, NULL);

    /* spawn a number of threads */
    for (i = 0; i < HELLOW_WORLD_MAX_LTHREADS; i++) {

        /*
         * Not strictly necessary but
         * for the sake of this example
         * use an attribute to pass the desired lcore
         */
        pthread_attr_t attr;
        rte_cpuset_t cpuset;

        CPU_ZERO(&cpuset);
        CPU_SET(lcore, &cpuset);
        pthread_attr_init(&attr);
        pthread_attr_setaffinity_np(&attr, sizeof(rte_cpuset_t), &cpuset);

        /* create the thread */
        ret = pthread_create(&tid[i], &attr,
                helloworld_pthread, (void *) i);
        if (ret != 0)
            rte_exit(EXIT_FAILURE, "Cannot create helloworld thread\n");
    }

    /* wait for 1s to allow threads
     * to block on the condition variable
     * N.B. nanosleep() is resolved to lthread_sleep()
     * by the shim.
     */
    struct timespec time;

    time.tv_sec = 1;
    time.tv_nsec = 0;
    nanosleep(&time, NULL);

    /* wake up all the threads */
    pthread_cond_broadcast(&exit_cond);

    /* wait for them to finish */
    for (i = 0; i < HELLOW_WORLD_MAX_LTHREADS; i++) {

        uint64_t thread_no;

        pthread_join(tid[i], (void *) &thread_no);
        if (thread_no != i)
            printf("error on thread exit\n");
    }

    pthread_cond_destroy(&exit_cond);
    pthread_mutex_destroy(&print_lock);
    pthread_mutex_destroy(&exit_lock);

    /* shutdown the lthread scheduler */
    lthread_scheduler_shutdown(rte_lcore_id());
    lthread_detach();
    return NULL;
}



/* This thread creates a single initial lthread
 * and then runs the scheduler
 * An instance of this thread is created on each thread
 * in the core mask
 */
static int
lthread_scheduler(void *args __attribute__((unused)))
{
    /* create initial thread  */
    struct lthread *lt;

    lthread_create(&lt, -1, initial_lthread, (void *) NULL);

    /* run the lthread scheduler */
    lthread_run();

    /* restore genuine pthread operation */
    pthread_override_set(0);
    return 0;
}

int main(int argc, char **argv)
{
    int num_sched = 0;

    /* basic DPDK initialization is all that is necessary to run lthreads*/
    int ret = rte_eal_init(argc, argv);

    if (ret < 0)
        rte_exit(EXIT_FAILURE, "Invalid EAL parameters\n");

    /* enable timer subsystem */
    rte_timer_subsystem_init();

#if DEBUG_APP
    lthread_diagnostic_set_mask(LT_DIAG_ALL);
#endif

    /* create a scheduler on every core in the core mask
     * and launch an initial lthread that will spawn many more.
     */
    unsigned lcore_id;

    for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
        if (rte_lcore_is_enabled(lcore_id))
            num_sched++;
    }

    /* set the number of schedulers, this forces all schedulers synchronize
     * before entering their main loop
     */
    lthread_num_schedulers_set(num_sched);

    /* launch all threads */
    rte_eal_mp_remote_launch(lthread_scheduler, (void *)NULL, CALL_MASTER);

    /* wait for threads to stop */
    RTE_LCORE_FOREACH_SLAVE(lcore_id) {
        rte_eal_wait_lcore(lcore_id);
    }

    /* clean up the EAL */
    rte_eal_cleanup();

    return 0;
}