calc_rate(rate_time, io_bytes, rate_io_bytes, rate);
memcpy(&rate_prev_time, &now, sizeof(now));
add_agg_sample(rate[DDIR_READ], DDIR_READ);
calc_rate(rate_time, io_bytes, rate_io_bytes, rate);
memcpy(&rate_prev_time, &now, sizeof(now));
add_agg_sample(rate[DDIR_READ], DDIR_READ);