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/* -*- c-file-style: "GNU" -*- */
/*
* Copyright (C) CNRS, INRIA, Université Bordeaux 1, Télécom SudParis
* See COPYING in top-level directory.
*/
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <semaphore.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdarg.h>
// Debugging part, print out only if debugging level of the system is verbose or more
int _debug = -77;
void debug(char *fmt, ...) {
if (_debug == -77) {
char *buf = getenv("EZTRACE_DEBUG");
if (buf == NULL)
_debug = 0;
else
_debug = atoi(buf);
}
if (_debug >= 0) { // debug verbose mode
va_list va;
va_start(va, fmt);
vfprintf(stdout, fmt, va);
va_end(va);
}
}
// end of debugging part
/* Number of iterations */
#define ITER 10
/* Number of threads */
#define NTH 2
typedef union {
unsigned long long tick;
struct {
unsigned low;
unsigned high;
};
} tick_t;
#define TICK_DIFF(t1, t2) \
((t2).tick - (t1).tick)
#define TIME_DIFF(t1, t2) \
((t2.tv_sec - t1.tv_sec) * 1000000 + (t2.tv_usec - t1.tv_usec))
/* Only used during thread creating to make sure that the thread
* got the correct args.
*/
sem_t thread_ready;
/* Block/unblock a thread */
sem_t sem[NTH];
pthread_mutex_t mutex;
/* Fake computation of usec microseconds */
void compute(int usec) {
struct timeval tv1, tv2;
gettimeofday(&tv1, NULL);
do {
gettimeofday(&tv2, NULL);
} while (TIME_DIFF(tv1, tv2) < usec);
}
void* f_thread(void* arg) {
int my_id = *(int*) arg;
/* Notify the main thread that we got the args */
sem_post(&thread_ready);
debug("Running thread #%d\n", my_id);
int i;
for (i = 0; i < ITER; i++) {
/* Wait until the previous thread has finished his job */
sem_wait(&sem[my_id]);
debug("[thread #%d] loop %d\n", my_id, i);
/* compute for 1ms */
pthread_mutex_lock(&mutex);
compute(50000);
pthread_mutex_unlock(&mutex);
compute(50000);
/* Wake up the next thread */
sem_post(&sem[(my_id + 1) % NTH]);
}
debug("End of thread #%d\n", my_id);
return NULL;
}
int main(int argc, char**argv) {
pthread_t tid[NTH];
int i;
pthread_mutex_init(&mutex, NULL);
sem_init(&thread_ready, 0, 0);
for (i = 0; i < NTH; i++)
sem_init(&sem[i], 0, 0);
for (i = 0; i < NTH; i++) {
pthread_create(&tid[i], NULL, f_thread, &i);
sem_wait(&thread_ready);
}
/* Unblock the first thread so that it can start working */
sem_post(&sem[0]);
for (i = 0; i < NTH; i++) {
pthread_join(tid[i], NULL);
}
return 0;
}
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