Blame gettime-thread.c

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#include <sys/time.h>
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#include <time.h>
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#include "fio.h"
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#include "smalloc.h"
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struct timespec *fio_ts = NULL;
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int fio_gtod_offload = 0;
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static pthread_t gtod_thread;
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static os_cpu_mask_t fio_gtod_cpumask;
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void fio_gtod_init(void)
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{
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	if (fio_ts)
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		return;
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	fio_ts = smalloc(sizeof(*fio_ts));
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}
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static void fio_gtod_update(void)
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{
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	if (fio_ts) {
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		struct timeval __tv;
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		gettimeofday(&__tv, NULL);
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		fio_ts->tv_sec = __tv.tv_sec;
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		write_barrier();
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		fio_ts->tv_nsec = __tv.tv_usec * 1000;
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		write_barrier();
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	}
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}
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struct gtod_cpu_data {
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	struct fio_sem *sem;
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	unsigned int cpu;
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};
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static void *gtod_thread_main(void *data)
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{
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	struct fio_sem *sem = data;
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	int ret;
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	ret = fio_setaffinity(gettid(), fio_gtod_cpumask);
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	fio_sem_up(sem);
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	if (ret == -1) {
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		log_err("gtod: setaffinity failed\n");
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		return NULL;
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	}
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	/*
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	 * As long as we have jobs around, update the clock. It would be nice
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	 * to have some way of NOT hammering that CPU with gettimeofday(),
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	 * but I'm not sure what to use outside of a simple CPU nop to relax
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	 * it - we don't want to lose precision.
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	 */
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	while (threads) {
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		fio_gtod_update();
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		nop;
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	}
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	return NULL;
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}
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int fio_start_gtod_thread(void)
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{
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	struct fio_sem *sem;
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	pthread_attr_t attr;
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	int ret;
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	sem = fio_sem_init(FIO_SEM_LOCKED);
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	if (!sem)
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		return 1;
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	pthread_attr_init(&attr);
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	pthread_attr_setstacksize(&attr, 2 * PTHREAD_STACK_MIN);
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	ret = pthread_create(&gtod_thread, &attr, gtod_thread_main, sem);
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	pthread_attr_destroy(&attr);
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	if (ret) {
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		log_err("Can't create gtod thread: %s\n", strerror(ret));
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		goto err;
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	}
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	ret = pthread_detach(gtod_thread);
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	if (ret) {
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		log_err("Can't detach gtod thread: %s\n", strerror(ret));
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		goto err;
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	}
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	dprint(FD_MUTEX, "wait on startup_sem\n");
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	fio_sem_down(sem);
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	dprint(FD_MUTEX, "done waiting on startup_sem\n");
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err:
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	fio_sem_remove(sem);
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	return ret;
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}
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void fio_gtod_set_cpu(unsigned int cpu)
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{
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#ifdef FIO_HAVE_CPU_AFFINITY
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	fio_cpu_set(&fio_gtod_cpumask, cpu);
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#endif
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}