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#include <pthread.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
int bench_nthread;
int bench_niter;
int grow_clock_var;
pthread_barrier_t glow_clock_barrier;
void bench(); // defined by user
void start_thread_group(int nth, void(*f)(int tid));
void grow_clock_worker(int tid);
int main(int argc, char **argv) {
bench_nthread = 2;
if (argc > 1)
bench_nthread = atoi(argv[1]);
bench_niter = 100;
if (argc > 2)
bench_niter = atoi(argv[2]);
// Grow thread's clock.
int clock_size = 10;
if (argc > 1)
clock_size = 1000;
pthread_barrier_init(&glow_clock_barrier, 0, clock_size);
start_thread_group(clock_size, grow_clock_worker);
pthread_barrier_destroy(&glow_clock_barrier);
__atomic_load_n(&grow_clock_var, __ATOMIC_ACQUIRE);
timespec tp0;
clock_gettime(CLOCK_MONOTONIC, &tp0);
bench();
timespec tp1;
clock_gettime(CLOCK_MONOTONIC, &tp1);
unsigned long long t =
(tp1.tv_sec * 1000000000ULL + tp1.tv_nsec) -
(tp0.tv_sec * 1000000000ULL + tp0.tv_nsec);
fprintf(stderr, "%llu ns/iter\n", t / bench_niter);
fprintf(stderr, "DONE\n");
}
void start_thread_group(int nth, void(*f)(int tid)) {
pthread_t *th = (pthread_t*)malloc(nth * sizeof(pthread_t));
for (int i = 0; i < nth; i++)
pthread_create(&th[i], 0, (void*(*)(void*))f, (void*)(long)i);
for (int i = 0; i < nth; i++)
pthread_join(th[i], 0);
}
void grow_clock_worker(int tid) {
int res = pthread_barrier_wait(&glow_clock_barrier);
if (res == PTHREAD_BARRIER_SERIAL_THREAD)
__atomic_store_n(&grow_clock_var, 0, __ATOMIC_RELEASE);
}
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