MS_IN_USEC
(bbr->r_ctl.rc_min_rto_ms * MS_IN_USEC),
sec = cts / MS_IN_USEC;
msec = cts - (MS_IN_USEC * sec);
return ((sec * USECS_IN_SECOND) + (msec * MS_IN_USEC));
t *= MS_IN_USEC;
rtt *= MS_IN_USEC;
rtt *= MS_IN_USEC;
#define USEC_TO_MSEC(x) (x / MS_IN_USEC)
#define BBR_TIME_TO_MILLI(a) (a / MS_IN_USEC)
#define BBR_TS_TO_MS(t) ((t+999)/MS_IN_USEC)