Run with intervals 100, 1000, 10000 as a command line input

usleep.cpp

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include <unistd.h>
#include <stdint.h>

#ifdef __APPLE__
#include <mach/mach_time.h>
#else
struct mach_timebase_info_data_t
{
    long numer, denom;
};

void mach_timebase_info(mach_timebase_info_data_t* out)
{
    out->numer = out->denom = 1;
}

uint64_t mach_absolute_time()
{
    struct timespec ts = {};
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return long(ts.tv_sec) * long(1e9) + ts.tv_nsec;
}
#endif

int main(int argc, char** argv)
{
	if (argc < 2)
	{
		printf("Usage: %s interval\n", argv[0]);
		return 1;
	}

	int interval = atoi(argv[1]);

	mach_timebase_info_data_t timebase = {};
	mach_timebase_info(&timebase);

	clock_t last_clock = clock();
	uint64_t last_time = mach_absolute_time();

	for (int i = 0; i < 100; ++i)
	{
		usleep(interval);

		clock_t cur_clock = clock();
		uint64_t cur_time = mach_absolute_time();

		printf("time delta %.1f us, clock delta %.0f us\n",
			double(cur_time - last_time) * double(timebase.numer) / double(timebase.denom) * 1e-3,
			double(cur_clock - last_clock) / double(CLOCKS_PER_SEC) * 1e6);

		last_clock = cur_clock;
		last_time = cur_time;
	}
}