nvml-sys 0.0.6

/*
 * Copyright 2015-2017, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 *     * Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * benchmark_time.cpp -- benchmark_time module definitions
 */
#include "benchmark_time.hpp"
#include "os.h"
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#define NSECPSEC 1000000000

/*
 * benchmark_time_get -- get timestamp from clock source
 */
void
benchmark_time_get(benchmark_time_t *time)
{
	os_clock_gettime(CLOCK_MONOTONIC, time);
}

/*
 * benchmark_time_diff -- get time interval
 */
void
benchmark_time_diff(benchmark_time_t *d, benchmark_time_t *t1,
		    benchmark_time_t *t2)
{
	long long nsecs = (t2->tv_sec - t1->tv_sec) * NSECPSEC + t2->tv_nsec -
		t1->tv_nsec;
	assert(nsecs >= 0);
	d->tv_sec = nsecs / NSECPSEC;
	d->tv_nsec = nsecs % NSECPSEC;
}

/*
 * benchmark_time_get_secs -- get total number of seconds
 */
double
benchmark_time_get_secs(benchmark_time_t *t)
{
	return (double)t->tv_sec + (double)t->tv_nsec / NSECPSEC;
}

/*
 * benchmark_time_get_nsecs -- get total number of nanoseconds
 */
unsigned long long
benchmark_time_get_nsecs(benchmark_time_t *t)
{
	unsigned long long ret = t->tv_nsec;

	ret += t->tv_sec * NSECPSEC;

	return ret;
}

/*
 * benchmark_time_compare -- compare two moments in time
 */
int
benchmark_time_compare(const benchmark_time_t *t1, const benchmark_time_t *t2)
{
	if (t1->tv_sec == t2->tv_sec)
		return (int)((long long)t1->tv_nsec - (long long)t2->tv_nsec);
	else
		return (int)((long long)t1->tv_sec - (long long)t2->tv_sec);
}

/*
 * benchmark_time_set -- set time using number of nanoseconds
 */
void
benchmark_time_set(benchmark_time_t *time, unsigned long long nsecs)
{
	time->tv_sec = nsecs / NSECPSEC;
	time->tv_nsec = nsecs % NSECPSEC;
}

/*
 * number of samples used to calculate average time required to get a current
 * time from the system
 */
#define N_PROBES_GET_TIME 10000000UL

/*
 * benchmark_get_avg_get_time -- calculates average time required to get the
 * current time from the system in nanoseconds
 */
unsigned long long
benchmark_get_avg_get_time(void)
{
	benchmark_time_t time;
	benchmark_time_t start;
	benchmark_time_t stop;

	benchmark_time_get(&start);
	for (size_t i = 0; i < N_PROBES_GET_TIME; i++) {
		benchmark_time_get(&time);
	}
	benchmark_time_get(&stop);

	benchmark_time_diff(&time, &start, &stop);

	unsigned long long avg =
		benchmark_time_get_nsecs(&time) / N_PROBES_GET_TIME;

	return avg;
}