Author: tuexen Date: Wed Feb 20 17:56:38 2019 New Revision: 344367 URL: https://svnweb.freebsd.org/changeset/base/344367
Log: Use exponential backoff for retransmitting SYN segments as specified in the TCP RFCs. Reviewed by: rrs@, Richard Scheffenegger Sponsored by: Netflix, Inc. Differential Revision: https://reviews.freebsd.org/D18974 Modified: head/sys/netinet/tcp_stacks/rack.c head/sys/netinet/tcp_syncache.c head/sys/netinet/tcp_timer.c head/sys/netinet/tcp_timer.h Modified: head/sys/netinet/tcp_stacks/rack.c ============================================================================== --- head/sys/netinet/tcp_stacks/rack.c Wed Feb 20 17:10:30 2019 (r344366) +++ head/sys/netinet/tcp_stacks/rack.c Wed Feb 20 17:56:38 2019 (r344367) @@ -2869,7 +2869,7 @@ rack_timeout_rxt(struct tcpcb *tp, struct tcp_rack *ra TCPSTAT_INC(tcps_rexmttimeo); if ((tp->t_state == TCPS_SYN_SENT) || (tp->t_state == TCPS_SYN_RECEIVED)) - rexmt = MSEC_2_TICKS(RACK_INITIAL_RTO * tcp_syn_backoff[tp->t_rxtshift]); + rexmt = MSEC_2_TICKS(RACK_INITIAL_RTO * tcp_backoff[tp->t_rxtshift]); else rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; TCPT_RANGESET(tp->t_rxtcur, rexmt, Modified: head/sys/netinet/tcp_syncache.c ============================================================================== --- head/sys/netinet/tcp_syncache.c Wed Feb 20 17:10:30 2019 (r344366) +++ head/sys/netinet/tcp_syncache.c Wed Feb 20 17:56:38 2019 (r344367) @@ -155,11 +155,11 @@ static int syncookie_cmp(struct in_conninfo *inc, str /* * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies. * 3 retransmits corresponds to a timeout with default values of - * TCPTV_RTOBASE * ( 1 + - * tcp_syn_backoff[1] + - * tcp_syn_backoff[2] + - * tcp_syn_backoff[3]) + 3 * tcp_rexmit_slop, - * 3000 ms * (1 + 1 + 1 + 1) + 3 * 200 ms = 12600 ms, + * TCPTV_RTOBASE * ( 1 + + * tcp_backoff[1] + + * tcp_backoff[2] + + * tcp_backoff[3]) + 3 * tcp_rexmit_slop, + * 3000 ms * (1 + 2 + 4 + 8) + 3 * 200 ms = 45600 ms, * the odds are that the user has given up attempting to connect by then. */ #define SYNCACHE_MAXREXMTS 3 @@ -426,7 +426,7 @@ syncache_timeout(struct syncache *sc, struct syncache_ if (sc->sc_rxmits == 0) rexmt = TCPTV_RTOBASE; else - TCPT_RANGESET(rexmt, TCPTV_RTOBASE * tcp_syn_backoff[sc->sc_rxmits], + TCPT_RANGESET(rexmt, TCPTV_RTOBASE * tcp_backoff[sc->sc_rxmits], tcp_rexmit_min, TCPTV_REXMTMAX); sc->sc_rxttime = ticks + rexmt; sc->sc_rxmits++; Modified: head/sys/netinet/tcp_timer.c ============================================================================== --- head/sys/netinet/tcp_timer.c Wed Feb 20 17:10:30 2019 (r344366) +++ head/sys/netinet/tcp_timer.c Wed Feb 20 17:56:38 2019 (r344367) @@ -233,9 +233,6 @@ tcp_slowtimo(void) VNET_LIST_RUNLOCK_NOSLEEP(); } -int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = - { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; - int tcp_backoff[TCP_MAXRXTSHIFT + 1] = { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; @@ -671,7 +668,7 @@ tcp_timer_rexmt(void * xtp) TCPSTAT_INC(tcps_rexmttimeo); if ((tp->t_state == TCPS_SYN_SENT) || (tp->t_state == TCPS_SYN_RECEIVED)) - rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; + rexmt = TCPTV_RTOBASE * tcp_backoff[tp->t_rxtshift]; else rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; TCPT_RANGESET(tp->t_rxtcur, rexmt, Modified: head/sys/netinet/tcp_timer.h ============================================================================== --- head/sys/netinet/tcp_timer.h Wed Feb 20 17:10:30 2019 (r344366) +++ head/sys/netinet/tcp_timer.h Wed Feb 20 17:56:38 2019 (r344367) @@ -199,7 +199,6 @@ extern int tcp_rexmit_slop; extern int tcp_msl; extern int tcp_ttl; /* time to live for TCP segs */ extern int tcp_backoff[]; -extern int tcp_syn_backoff[]; extern int tcp_totbackoff; extern int tcp_rexmit_drop_options; _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
