1#include <pthread.h>
2#include <stdlib.h>
3#include <stddef.h>
4#include <unistd.h>
5#include <stdio.h>
6#include <time.h>
7
8int bench_nthread;
9int bench_niter;
10int grow_clock_var;
11pthread_barrier_t glow_clock_barrier;
12
13void bench(); // defined by user
14void start_thread_group(int nth, void(*f)(int tid));
15void grow_clock_worker(int tid);
16
17int main(int argc, char **argv) {
18 bench_nthread = 2;
19 if (argc > 1)
20 bench_nthread = atoi(argv[1]);
21 bench_niter = 100;
22 if (argc > 2)
23 bench_niter = atoi(argv[2]);
24
25 // Grow thread's clock.
26 int clock_size = 10;
27 if (argc > 1)
28 clock_size = 1000;
29 pthread_barrier_init(&glow_clock_barrier, 0, clock_size);
30 start_thread_group(clock_size, grow_clock_worker);
31 pthread_barrier_destroy(&glow_clock_barrier);
32 __atomic_load_n(&grow_clock_var, __ATOMIC_ACQUIRE);
33
34 timespec tp0;
35 clock_gettime(CLOCK_MONOTONIC, &tp0);
36 bench();
37 timespec tp1;
38 clock_gettime(CLOCK_MONOTONIC, &tp1);
39 unsigned long long t =
40 (tp1.tv_sec * 1000000000ULL + tp1.tv_nsec) -
41 (tp0.tv_sec * 1000000000ULL + tp0.tv_nsec);
42 fprintf(stderr, "%llu ns/iter\n", t / bench_niter);
43 fprintf(stderr, "DONE\n");
44}
45
46void start_thread_group(int nth, void(*f)(int tid)) {
47 pthread_t *th = (pthread_t*)malloc(nth * sizeof(pthread_t));
48 for (int i = 0; i < nth; i++)
49 pthread_create(&th[i], 0, (void*(*)(void*))f, (void*)(long)i);
50 for (int i = 0; i < nth; i++)
51 pthread_join(th[i], 0);
52}
53
54void grow_clock_worker(int tid) {
55 int res = pthread_barrier_wait(&glow_clock_barrier);
56 if (res == PTHREAD_BARRIER_SERIAL_THREAD)
57 __atomic_store_n(&grow_clock_var, 0, __ATOMIC_RELEASE);
58}
59
60