File: gettime.c

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/*
 * Clock functions
 */

#include <unistd.h>
#include <sys/time.h>

#include "fio.h"
#include "smalloc.h"

#include "hash.h"

static int clock_gettime_works = 0;
static struct timeval last_tv;
static int last_tv_valid;

static struct timeval *fio_tv;
int fio_gtod_offload = 0;
int fio_gtod_cpu = -1;

#ifdef FIO_DEBUG_TIME

#define HASH_BITS	8
#define HASH_SIZE	(1 << HASH_BITS)

static struct flist_head hash[HASH_SIZE];
static int gtod_inited;

struct gtod_log {
	struct flist_head list;
	void *caller;
	unsigned long calls;
};

static struct gtod_log *find_hash(void *caller)
{
	unsigned long h = hash_ptr(caller, HASH_BITS);
	struct flist_head *entry;

	flist_for_each(entry, &hash[h]) {
		struct gtod_log *log = flist_entry(entry, struct gtod_log,
									list);

		if (log->caller == caller)
			return log;
	}

	return NULL;
}

static struct gtod_log *find_log(void *caller)
{
	struct gtod_log *log = find_hash(caller);

	if (!log) {
		unsigned long h;

		log = malloc(sizeof(*log));
		INIT_FLIST_HEAD(&log->list);
		log->caller = caller;
		log->calls = 0;

		h = hash_ptr(caller, HASH_BITS);
		flist_add_tail(&log->list, &hash[h]);
	}

	return log;
}

static void gtod_log_caller(void *caller)
{
	if (gtod_inited) {
		struct gtod_log *log = find_log(caller);

		log->calls++;
	}
}

static void fio_exit fio_dump_gtod(void)
{
	unsigned long total_calls = 0;
	int i;

	for (i = 0; i < HASH_SIZE; i++) {
		struct flist_head *entry;
		struct gtod_log *log;

		flist_for_each(entry, &hash[i]) {
			log = flist_entry(entry, struct gtod_log, list);

			printf("function %p, calls %lu\n", log->caller,
								log->calls);
			total_calls += log->calls;
		}
	}

	printf("Total %lu gettimeofday\n", total_calls);
}

static void fio_init gtod_init(void)
{
	int i;

	for (i = 0; i < HASH_SIZE; i++)
		INIT_FLIST_HEAD(&hash[i]);

	gtod_inited = 1;
}

#endif /* FIO_DEBUG_TIME */

#ifdef FIO_DEBUG_TIME
void fio_gettime(struct timeval *tp, void *caller)
#else
void fio_gettime(struct timeval *tp, void fio_unused *caller)
#endif
{
#ifdef FIO_DEBUG_TIME
	if (!caller)
		caller = __builtin_return_address(0);

	gtod_log_caller(caller);
#endif
	if (fio_tv) {
		memcpy(tp, fio_tv, sizeof(*tp));
		return;
	} else if (!clock_gettime_works) {
gtod:
		gettimeofday(tp, NULL);
	} else {
		struct timespec ts;

		if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
			clock_gettime_works = 0;
			goto gtod;
		}

		tp->tv_sec = ts.tv_sec;
		tp->tv_usec = ts.tv_nsec / 1000;
	}

	/*
	 * If Linux is using the tsc clock on non-synced processors,
	 * sometimes time can appear to drift backwards. Fix that up.
	 */
	if (last_tv_valid) {
		if (tp->tv_sec < last_tv.tv_sec)
			tp->tv_sec = last_tv.tv_sec;
		else if (last_tv.tv_sec == tp->tv_sec &&
			 tp->tv_usec < last_tv.tv_usec)
			tp->tv_usec = last_tv.tv_usec;
	}
	last_tv_valid = 1;
	memcpy(&last_tv, tp, sizeof(*tp));
}

void fio_gtod_init(void)
{
	fio_tv = smalloc(sizeof(struct timeval));
	assert(fio_tv);
}

void fio_gtod_update(void)
{
	gettimeofday(fio_tv, NULL);
}