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      1 #include <unistd.h>
      2 #include <math.h>
      3 #include <sys/time.h>
      4 #include <time.h>
      5 
      6 #include "fio.h"
      7 #include "smalloc.h"
      8 
      9 struct timeval *fio_tv = NULL;
     10 int fio_gtod_offload = 0;
     11 static pthread_t gtod_thread;
     12 #ifdef FIO_HAVE_CPU_AFFINITY
     13 static os_cpu_mask_t fio_gtod_cpumask;
     14 #endif
     15 
     16 void fio_gtod_init(void)
     17 {
     18 	if (fio_tv)
     19 		return;
     20 
     21 	fio_tv = smalloc(sizeof(struct timeval));
     22 	if (!fio_tv)
     23 		log_err("fio: smalloc pool exhausted\n");
     24 }
     25 
     26 static void fio_gtod_update(void)
     27 {
     28 	if (fio_tv) {
     29 		struct timeval __tv;
     30 
     31 		gettimeofday(&__tv, NULL);
     32 		fio_tv->tv_sec = __tv.tv_sec;
     33 		write_barrier();
     34 		fio_tv->tv_usec = __tv.tv_usec;
     35 		write_barrier();
     36 	}
     37 }
     38 
     39 struct gtod_cpu_data {
     40 	struct fio_mutex *mutex;
     41 	unsigned int cpu;
     42 };
     43 
     44 static void *gtod_thread_main(void *data)
     45 {
     46 	struct fio_mutex *mutex = data;
     47 
     48 	fio_setaffinity(gettid(), fio_gtod_cpumask);
     49 	fio_mutex_up(mutex);
     50 
     51 	/*
     52 	 * As long as we have jobs around, update the clock. It would be nice
     53 	 * to have some way of NOT hammering that CPU with gettimeofday(),
     54 	 * but I'm not sure what to use outside of a simple CPU nop to relax
     55 	 * it - we don't want to lose precision.
     56 	 */
     57 	while (threads) {
     58 		fio_gtod_update();
     59 		nop;
     60 	}
     61 
     62 	return NULL;
     63 }
     64 
     65 int fio_start_gtod_thread(void)
     66 {
     67 	struct fio_mutex *mutex;
     68 	pthread_attr_t attr;
     69 	int ret;
     70 
     71 	mutex = fio_mutex_init(FIO_MUTEX_LOCKED);
     72 	if (!mutex)
     73 		return 1;
     74 
     75 	pthread_attr_init(&attr);
     76 	pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN);
     77 	ret = pthread_create(&gtod_thread, &attr, gtod_thread_main, mutex);
     78 	pthread_attr_destroy(&attr);
     79 	if (ret) {
     80 		log_err("Can't create gtod thread: %s\n", strerror(ret));
     81 		goto err;
     82 	}
     83 
     84 	ret = pthread_detach(gtod_thread);
     85 	if (ret) {
     86 		log_err("Can't detatch gtod thread: %s\n", strerror(ret));
     87 		goto err;
     88 	}
     89 
     90 	dprint(FD_MUTEX, "wait on startup_mutex\n");
     91 	fio_mutex_down(mutex);
     92 	dprint(FD_MUTEX, "done waiting on startup_mutex\n");
     93 err:
     94 	fio_mutex_remove(mutex);
     95 	return ret;
     96 }
     97 
     98 void fio_gtod_set_cpu(unsigned int cpu)
     99 {
    100 #ifdef FIO_HAVE_CPU_AFFINITY
    101 	fio_cpu_set(&fio_gtod_cpumask, cpu);
    102 #endif
    103 }
    104