rack_get_output_gain
log.u_bbr.pacing_gain = rack_get_output_gain(rack, rsm);
gain = rack_get_output_gain(rack, NULL);
log.u_bbr.pacing_gain = rack_get_output_gain(rack, NULL);
log.u_bbr.pacing_gain = rack_get_output_gain(rack, NULL);
log.u_bbr.pacing_gain = rack_get_output_gain(rack, NULL);
log.u_bbr.pacing_gain = rack_get_output_gain(rack, rsm);
gain = (uint64_t)rack_get_output_gain(rack, rsm);