bbr_log_to_start
bbr_log_to_start(struct tcp_bbr *bbr, uint32_t cts, uint32_t to, int32_t pacing_delay,
bbr_log_to_start(bbr, cts, hpts_timeout, pacing_delay, 1);
bbr_log_to_start(bbr, cts, hpts_timeout, pacing_delay, 0);