now = time.time()
next_time = start_time + (1.0/rate) * count
time.sleep(max(0.0, next_time - now))
last_time = time.time()
latencies.append(write_file(path, count))
now = time.time()
next_time = start_time + (1.0/rate) * count
time.sleep(max(0.0, next_time - now))
last_time = time.time()
latencies.append(write_file(path, count))