acfe4c4467
from Larry Peterson &co. at Arizona: - Header prediction for ACKs did not exclude Fast Retransmit/Recovery. - srtt calculation tended to get ``stuck'' and could never decrease when below 8. It still can't, but the scaling factors are adjusted so that this artifact does not cause as bad an effect on the RTO value as it used to. The paper also points out the incr/8 error that has been long since fixed, and the problems with ACKing frequency resulting from the use of options which I suspect to be fixed already as well (as part of the T/TCP work). Obtained from: Brakmo & Peterson, ``Performance Problems in BSD4.4 TCP''
391 lines
16 KiB
C
391 lines
16 KiB
C
/*
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* Copyright (c) 1982, 1986, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_var.h 8.4 (Berkeley) 5/24/95
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* $Id: tcp_var.h,v 1.30 1996/02/27 15:12:53 bde Exp $
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*/
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#ifndef _NETINET_TCP_VAR_H_
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#define _NETINET_TCP_VAR_H_
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/*
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* Kernel variables for tcp.
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*/
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/*
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* Tcp control block, one per tcp; fields:
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*/
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struct tcpcb {
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struct tcpiphdr *seg_next; /* sequencing queue */
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struct tcpiphdr *seg_prev;
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int t_state; /* state of this connection */
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int t_timer[TCPT_NTIMERS]; /* tcp timers */
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int t_rxtshift; /* log(2) of rexmt exp. backoff */
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int t_rxtcur; /* current retransmit value */
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int t_dupacks; /* consecutive dup acks recd */
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u_int t_maxseg; /* maximum segment size */
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u_int t_maxopd; /* mss plus options */
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int t_force; /* 1 if forcing out a byte */
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u_int t_flags;
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#define TF_ACKNOW 0x0001 /* ack peer immediately */
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#define TF_DELACK 0x0002 /* ack, but try to delay it */
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#define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
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#define TF_NOOPT 0x0008 /* don't use tcp options */
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#define TF_SENTFIN 0x0010 /* have sent FIN */
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#define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
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#define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
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#define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
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#define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
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#define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
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#define TF_NEEDSYN 0x0400 /* send SYN (implicit state) */
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#define TF_NEEDFIN 0x0800 /* send FIN (implicit state) */
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#define TF_NOPUSH 0x1000 /* don't push */
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#define TF_REQ_CC 0x2000 /* have/will request CC */
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#define TF_RCVD_CC 0x4000 /* a CC was received in SYN */
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#define TF_SENDCCNEW 0x8000 /* send CCnew instead of CC in SYN */
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struct tcpiphdr *t_template; /* skeletal packet for transmit */
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struct inpcb *t_inpcb; /* back pointer to internet pcb */
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/*
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* The following fields are used as in the protocol specification.
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* See RFC783, Dec. 1981, page 21.
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*/
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/* send sequence variables */
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tcp_seq snd_una; /* send unacknowledged */
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tcp_seq snd_nxt; /* send next */
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tcp_seq snd_up; /* send urgent pointer */
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tcp_seq snd_wl1; /* window update seg seq number */
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tcp_seq snd_wl2; /* window update seg ack number */
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tcp_seq iss; /* initial send sequence number */
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u_long snd_wnd; /* send window */
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/* receive sequence variables */
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u_long rcv_wnd; /* receive window */
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tcp_seq rcv_nxt; /* receive next */
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tcp_seq rcv_up; /* receive urgent pointer */
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tcp_seq irs; /* initial receive sequence number */
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/*
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* Additional variables for this implementation.
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*/
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/* receive variables */
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tcp_seq rcv_adv; /* advertised window */
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/* retransmit variables */
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tcp_seq snd_max; /* highest sequence number sent;
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* used to recognize retransmits
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*/
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/* congestion control (for slow start, source quench, retransmit after loss) */
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u_long snd_cwnd; /* congestion-controlled window */
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u_long snd_ssthresh; /* snd_cwnd size threshold for
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* for slow start exponential to
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* linear switch
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*/
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/*
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* transmit timing stuff. See below for scale of srtt and rttvar.
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* "Variance" is actually smoothed difference.
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*/
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u_int t_idle; /* inactivity time */
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int t_rtt; /* round trip time */
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tcp_seq t_rtseq; /* sequence number being timed */
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int t_srtt; /* smoothed round-trip time */
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int t_rttvar; /* variance in round-trip time */
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u_int t_rttmin; /* minimum rtt allowed */
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u_long max_sndwnd; /* largest window peer has offered */
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/* out-of-band data */
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char t_oobflags; /* have some */
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char t_iobc; /* input character */
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#define TCPOOB_HAVEDATA 0x01
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#define TCPOOB_HADDATA 0x02
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int t_softerror; /* possible error not yet reported */
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/* RFC 1323 variables */
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u_char snd_scale; /* window scaling for send window */
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u_char rcv_scale; /* window scaling for recv window */
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u_char request_r_scale; /* pending window scaling */
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u_char requested_s_scale;
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u_long ts_recent; /* timestamp echo data */
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u_long ts_recent_age; /* when last updated */
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tcp_seq last_ack_sent;
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/* RFC 1644 variables */
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tcp_cc cc_send; /* send connection count */
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tcp_cc cc_recv; /* receive connection count */
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u_long t_duration; /* connection duration */
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/* TUBA stuff */
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caddr_t t_tuba_pcb; /* next level down pcb for TCP over z */
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/* More RTT stuff */
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u_long t_rttupdated; /* number of times rtt sampled */
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};
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/*
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* Structure to hold TCP options that are only used during segment
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* processing (in tcp_input), but not held in the tcpcb.
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* It's basically used to reduce the number of parameters
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* to tcp_dooptions.
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*/
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struct tcpopt {
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u_long to_flag; /* which options are present */
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#define TOF_TS 0x0001 /* timestamp */
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#define TOF_CC 0x0002 /* CC and CCnew are exclusive */
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#define TOF_CCNEW 0x0004
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#define TOF_CCECHO 0x0008
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u_long to_tsval;
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u_long to_tsecr;
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tcp_cc to_cc; /* holds CC or CCnew */
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tcp_cc to_ccecho;
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};
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/*
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* The TAO cache entry which is stored in the protocol family specific
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* portion of the route metrics.
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*/
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struct rmxp_tao {
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tcp_cc tao_cc; /* latest CC in valid SYN */
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tcp_cc tao_ccsent; /* latest CC sent to peer */
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u_short tao_mssopt; /* peer's cached MSS */
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#ifdef notyet
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u_short tao_flags; /* cache status flags */
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#define TAOF_DONT 0x0001 /* peer doesn't understand rfc1644 */
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#define TAOF_OK 0x0002 /* peer does understand rfc1644 */
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#define TAOF_UNDEF 0 /* we don't know yet */
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#endif /* notyet */
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};
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#define rmx_taop(r) ((struct rmxp_tao *)(r).rmx_filler)
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#define intotcpcb(ip) ((struct tcpcb *)(ip)->inp_ppcb)
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#define sototcpcb(so) (intotcpcb(sotoinpcb(so)))
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/*
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* The smoothed round-trip time and estimated variance
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* are stored as fixed point numbers scaled by the values below.
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* For convenience, these scales are also used in smoothing the average
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* (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
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* With these scales, srtt has 3 bits to the right of the binary point,
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* and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
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* binary point, and is smoothed with an ALPHA of 0.75.
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*/
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#ifdef notdef
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#define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
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#define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
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#define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
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#define TCP_RTTVAR_SHIFT 2 /* shift for rttvar; 2 bits */
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#else
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#define TCP_RTT_SCALE 32 /* multiplier for srtt; 3 bits frac. */
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#define TCP_RTT_SHIFT 5 /* shift for srtt; 3 bits frac. */
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#define TCP_RTTVAR_SCALE 16 /* multiplier for rttvar; 2 bits */
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#define TCP_RTTVAR_SHIFT 4 /* shift for rttvar; 2 bits */
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#define TCP_DELTA_SHIFT 2 /* see tcp_input.c */
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#endif
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/*
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* The initial retransmission should happen at rtt + 4 * rttvar.
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* Because of the way we do the smoothing, srtt and rttvar
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* will each average +1/2 tick of bias. When we compute
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* the retransmit timer, we want 1/2 tick of rounding and
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* 1 extra tick because of +-1/2 tick uncertainty in the
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* firing of the timer. The bias will give us exactly the
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* 1.5 tick we need. But, because the bias is
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* statistical, we have to test that we don't drop below
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* the minimum feasible timer (which is 2 ticks).
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#ifdef notdef
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* This macro assumes that the value of TCP_RTTVAR_SCALE
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* is the same as the multiplier for rttvar.
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#else
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* This version of the macro adapted from a paper by Lawrence
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* Brakmo and Larry Peterson which outlines a problem caused
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* by insufficient precision in the original implementation,
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* which results in inappropriately large RTO values for very
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* fast networks.
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#endif
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*/
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#ifdef notdef
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#define TCP_REXMTVAL(tp) \
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(((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
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#else
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#define TCP_REXMTVAL(tp) \
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((((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT)) \
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+ ((tp)->t_rttvar) >> TCP_RTTVAR_SHIFT))
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#endif
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/* XXX
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* We want to avoid doing m_pullup on incoming packets but that
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* means avoiding dtom on the tcp reassembly code. That in turn means
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* keeping an mbuf pointer in the reassembly queue (since we might
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* have a cluster). As a quick hack, the source & destination
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* port numbers (which are no longer needed once we've located the
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* tcpcb) are overlayed with an mbuf pointer.
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*/
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#define REASS_MBUF(ti) (*(struct mbuf **)&((ti)->ti_t))
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/*
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* TCP statistics.
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* Many of these should be kept per connection,
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* but that's inconvenient at the moment.
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*/
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struct tcpstat {
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u_long tcps_connattempt; /* connections initiated */
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u_long tcps_accepts; /* connections accepted */
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u_long tcps_connects; /* connections established */
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u_long tcps_drops; /* connections dropped */
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u_long tcps_conndrops; /* embryonic connections dropped */
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u_long tcps_closed; /* conn. closed (includes drops) */
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u_long tcps_segstimed; /* segs where we tried to get rtt */
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u_long tcps_rttupdated; /* times we succeeded */
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u_long tcps_delack; /* delayed acks sent */
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u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
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u_long tcps_rexmttimeo; /* retransmit timeouts */
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u_long tcps_persisttimeo; /* persist timeouts */
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u_long tcps_keeptimeo; /* keepalive timeouts */
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u_long tcps_keepprobe; /* keepalive probes sent */
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u_long tcps_keepdrops; /* connections dropped in keepalive */
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u_long tcps_sndtotal; /* total packets sent */
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u_long tcps_sndpack; /* data packets sent */
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u_long tcps_sndbyte; /* data bytes sent */
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u_long tcps_sndrexmitpack; /* data packets retransmitted */
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u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
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u_long tcps_sndacks; /* ack-only packets sent */
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u_long tcps_sndprobe; /* window probes sent */
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u_long tcps_sndurg; /* packets sent with URG only */
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u_long tcps_sndwinup; /* window update-only packets sent */
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u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */
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u_long tcps_rcvtotal; /* total packets received */
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u_long tcps_rcvpack; /* packets received in sequence */
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u_long tcps_rcvbyte; /* bytes received in sequence */
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u_long tcps_rcvbadsum; /* packets received with ccksum errs */
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u_long tcps_rcvbadoff; /* packets received with bad offset */
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u_long tcps_rcvshort; /* packets received too short */
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u_long tcps_rcvduppack; /* duplicate-only packets received */
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u_long tcps_rcvdupbyte; /* duplicate-only bytes received */
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u_long tcps_rcvpartduppack; /* packets with some duplicate data */
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u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */
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u_long tcps_rcvoopack; /* out-of-order packets received */
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u_long tcps_rcvoobyte; /* out-of-order bytes received */
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u_long tcps_rcvpackafterwin; /* packets with data after window */
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u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */
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u_long tcps_rcvafterclose; /* packets rcvd after "close" */
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u_long tcps_rcvwinprobe; /* rcvd window probe packets */
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u_long tcps_rcvdupack; /* rcvd duplicate acks */
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u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */
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u_long tcps_rcvackpack; /* rcvd ack packets */
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u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */
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u_long tcps_rcvwinupd; /* rcvd window update packets */
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u_long tcps_pawsdrop; /* segments dropped due to PAWS */
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u_long tcps_predack; /* times hdr predict ok for acks */
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u_long tcps_preddat; /* times hdr predict ok for data pkts */
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u_long tcps_pcbcachemiss;
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u_long tcps_cachedrtt; /* times cached RTT in route updated */
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u_long tcps_cachedrttvar; /* times cached rttvar updated */
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u_long tcps_cachedssthresh; /* times cached ssthresh updated */
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u_long tcps_usedrtt; /* times RTT initialized from route */
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u_long tcps_usedrttvar; /* times RTTVAR initialized from rt */
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u_long tcps_usedssthresh; /* times ssthresh initialized from rt*/
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u_long tcps_persistdrop; /* timeout in persist state */
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u_long tcps_badsyn; /* bogus SYN, e.g. premature ACK */
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u_long tcps_mturesent; /* resends due to MTU discovery */
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u_long tcps_listendrop; /* listen queue overflows */
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};
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/*
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* Names for TCP sysctl objects
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*/
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#define TCPCTL_DO_RFC1323 1 /* use RFC-1323 extensions */
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#define TCPCTL_DO_RFC1644 2 /* use RFC-1644 extensions */
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#define TCPCTL_MSSDFLT 3 /* MSS default */
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#define TCPCTL_STATS 4 /* statistics (read-only) */
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#define TCPCTL_RTTDFLT 5 /* default RTT estimate */
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#define TCPCTL_KEEPIDLE 6 /* keepalive idle timer */
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#define TCPCTL_KEEPINTVL 7 /* interval to send keepalives */
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#define TCPCTL_SENDSPACE 8 /* send buffer space */
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#define TCPCTL_RECVSPACE 9 /* receive buffer space */
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#define TCPCTL_MAXID 10
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#define TCPCTL_NAMES { \
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{ 0, 0 }, \
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{ "rfc1323", CTLTYPE_INT }, \
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{ "rfc1644", CTLTYPE_INT }, \
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{ "mssdflt", CTLTYPE_INT }, \
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{ "stats", CTLTYPE_STRUCT }, \
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{ "rttdflt", CTLTYPE_INT }, \
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{ "keepidle", CTLTYPE_INT }, \
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{ "keepintvl", CTLTYPE_INT }, \
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{ "sendspace", CTLTYPE_INT }, \
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{ "recvspace", CTLTYPE_INT }, \
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}
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#ifdef KERNEL
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extern struct inpcbhead tcb; /* head of queue of active tcpcb's */
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extern struct inpcbinfo tcbinfo;
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extern struct tcpstat tcpstat; /* tcp statistics */
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extern int tcp_mssdflt; /* XXX */
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extern u_long tcp_now; /* for RFC 1323 timestamps */
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void tcp_canceltimers __P((struct tcpcb *));
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struct tcpcb *
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tcp_close __P((struct tcpcb *));
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void tcp_ctlinput __P((int, struct sockaddr *, void *));
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int tcp_ctloutput __P((int, struct socket *, int, int, struct mbuf **));
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struct tcpcb *
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tcp_drop __P((struct tcpcb *, int));
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void tcp_drain __P((void));
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void tcp_fasttimo __P((void));
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struct rmxp_tao *
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tcp_gettaocache __P((struct inpcb *));
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void tcp_init __P((void));
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void tcp_input __P((struct mbuf *, int));
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void tcp_mss __P((struct tcpcb *, int));
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int tcp_mssopt __P((struct tcpcb *));
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void tcp_mtudisc __P((struct inpcb *, int));
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struct tcpcb *
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tcp_newtcpcb __P((struct inpcb *));
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int tcp_output __P((struct tcpcb *));
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void tcp_quench __P((struct inpcb *, int));
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void tcp_respond __P((struct tcpcb *,
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struct tcpiphdr *, struct mbuf *, u_long, u_long, int));
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struct rtentry *
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tcp_rtlookup __P((struct inpcb *));
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void tcp_setpersist __P((struct tcpcb *));
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void tcp_slowtimo __P((void));
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struct tcpiphdr *
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tcp_template __P((struct tcpcb *));
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struct tcpcb *
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tcp_timers __P((struct tcpcb *, int));
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void tcp_trace __P((int, int, struct tcpcb *, struct tcpiphdr *, int));
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int tcp_usrreq __P((struct socket *,
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int, struct mbuf *, struct mbuf *, struct mbuf *));
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extern u_long tcp_sendspace;
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extern u_long tcp_recvspace;
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#endif /* KERNEL */
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#endif /* _NETINET_TCP_VAR_H_ */
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