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