diff options
Diffstat (limited to 'sys/netinet/tcp_output.c')
| -rw-r--r-- | sys/netinet/tcp_output.c | 88 |
1 files changed, 73 insertions, 15 deletions
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c index ead2c1a..3479c1d 100644 --- a/sys/netinet/tcp_output.c +++ b/sys/netinet/tcp_output.c @@ -105,6 +105,10 @@ int tcp_do_newreno = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, newreno, CTLFLAG_RW, &tcp_do_newreno, 0, "Enable NewReno Algorithms"); +int tcp_do_tso = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_RW, + &tcp_do_tso, 0, "Enable TCP Segmentation Offload"); + /* * Tcp output routine: figure out what should be sent and send it. */ @@ -127,6 +131,7 @@ tcp_output(struct tcpcb *tp) int i, sack_rxmit; int sack_bytes_rxmt; struct sackhole *p; + int tso = 0; #if 0 int maxburst = TCP_MAXBURST; #endif @@ -376,12 +381,34 @@ after_sack_rexmit: /* * len will be >= 0 after this point. Truncate to the maximum - * segment length and ensure that FIN is removed if the length - * no longer contains the last data byte. + * segment length or enable TCP Segmentation Offloading (if supported + * by hardware) and ensure that FIN is removed if the length no longer + * contains the last data byte. + * + * TSO may only be used if we are in a pure bulk sending state. The + * presence of TCP-MD5, SACK retransmits, SACK advertizements and + * IP options prevent using TSO. With TSO the TCP header is the same + * (except for the sequence number) for all generated packets. This + * makes it impossible to transmit any options which vary per generated + * segment or packet. + * + * The length of TSO bursts is limited to TCP_MAXWIN. That limit and + * removal of FIN (if not already catched here) are handled later after + * the exact length of the TCP options are known. */ if (len > tp->t_maxseg) { - len = tp->t_maxseg; - sendalot = 1; + if ((tp->t_flags & TF_TSO) && tcp_do_tso && + ((tp->t_flags & TF_SIGNATURE) == 0) && + tp->rcv_numsacks == 0 && sack_rxmit == 0 && + tp->t_inpcb->inp_options == NULL && + tp->t_inpcb->in6p_options == NULL && + tp->t_inpcb->inp_sp == NULL) { + tso = 1; + } else { + len = tp->t_maxseg; + sendalot = 1; + tso = 0; + } } if (sack_rxmit) { if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) @@ -397,7 +424,7 @@ after_sack_rexmit: * Sender silly window avoidance. We transmit under the following * conditions when len is non-zero: * - * - We have a full segment + * - We have a full segment (or more with TSO) * - This is the last buffer in a write()/send() and we are * either idle or running NODELAY * - we've timed out (e.g. persist timer) @@ -406,7 +433,7 @@ after_sack_rexmit: * - we need to retransmit */ if (len) { - if (len == tp->t_maxseg) + if (len >= tp->t_maxseg) goto send; /* * NOTE! on localhost connections an 'ack' from the remote @@ -702,14 +729,24 @@ send: * bump the packet length beyond the t_maxopd length. * Clear the FIN bit because we cut off the tail of * the segment. + * + * When doing TSO limit a burst to TCP_MAXWIN and set the + * flag to continue sending and prevent the last segment + * from being fractional thus making them all equal sized. */ if (len + optlen + ipoptlen > tp->t_maxopd) { - /* - * If there is still more to send, don't close the connection. - */ flags &= ~TH_FIN; - len = tp->t_maxopd - optlen - ipoptlen; - sendalot = 1; + if (tso) { + if (len > TCP_MAXWIN) { + len = TCP_MAXWIN - TCP_MAXWIN % + (tp->t_maxopd - optlen); + sendalot = 1; + } else if (tp->t_flags & TF_NEEDFIN) + sendalot = 1; + } else { + len = tp->t_maxopd - optlen - ipoptlen; + sendalot = 1; + } } /*#ifdef DIAGNOSTIC*/ @@ -947,6 +984,16 @@ send: } /* + * Enable TSO and specify the size of the segments. + * The TCP pseudo header checksum is always provided. + * XXX: Fixme: This is currently not the case for IPv6. + */ + if (tso) { + m->m_pkthdr.csum_flags = CSUM_TSO; + m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen; + } + + /* * In transmit state, time the transmission and arrange for * the retransmit. In persist state, just set snd_max. */ @@ -1119,11 +1166,22 @@ out: } if (error == EMSGSIZE) { /* - * ip_output() will have already fixed the route - * for us. tcp_mtudisc() will, as its last action, - * initiate retransmission, so it is important to - * not do so here. + * For some reason the interface we used initially + * to send segments changed to another or lowered + * its MTU. + * + * tcp_mtudisc() will find out the new MTU and as + * its last action, initiate retransmission, so it + * is important to not do so here. + * + * If TSO was active we either got an interface + * without TSO capabilits or TSO was turned off. + * Disable it for this connection as too and + * immediatly retry with MSS sized segments generated + * by this function. */ + if (tso) + tp->t_flags &= ~TF_TSO; tcp_mtudisc(tp->t_inpcb, 0); return 0; } |
