FreeBSD/Linux Kernel Cross Reference
sys/netinet/khelp/h_ertt.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2009-2010
      *      Swinburne University of Technology, Melbourne, Australia
      * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
      * All rights reserved.
      *
      * This software was developed at the Centre for Advanced Internet
     * Architectures, Swinburne University of Technology, by David Hayes, made
     * possible in part by a grant from the Cisco University Research Program Fund
     * at Community Foundation Silicon Valley.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    /*
     * The ERTT (Enhanced Round Trip Time) Khelp module calculates an estimate of
     * the instantaneous TCP RTT which, for example, is used by delay-based
     * congestion control schemes. When the module is loaded, ERTT data is
     * calculated for each active TCP connection and encapsulated within a
     * "struct ertt".
     *
     * This software was first released in 2010 by David Hayes and Lawrence Stewart
     * whilst working on the NewTCP research project at Swinburne University of
     * Technology's Centre for Advanced Internet Architectures, Melbourne,
     * Australia, which was made possible in part by a grant from the Cisco
     * University Research Program Fund at Community Foundation Silicon Valley.
     * Testing and development was further assisted by a grant from the FreeBSD
     * Foundation. More details are available at:
     *   http://caia.swin.edu.au/urp/newtcp/
     */
    
    #ifndef _NETINET_KHELP_H_ERTT_
    #define _NETINET_KHELP_H_ERTT_
    
    struct txseginfo;
    
    /* Structure used as the ertt data block. */
    struct ertt {
            /* Information about transmitted segments to aid in RTT calculation. */
            TAILQ_HEAD(txseginfo_head, txseginfo) txsegi_q;
            /* Bytes TX so far in marked RTT. */
            long            bytes_tx_in_rtt;
            /* Final version of above. */
            long            bytes_tx_in_marked_rtt;
            /* cwnd for marked RTT. */
            unsigned long   marked_snd_cwnd;
            /* Per-packet measured RTT. */
            int             rtt;
            /* Maximum RTT measured. */
            int             maxrtt;
            /* Minimum RTT measured. */
            int             minrtt;
            /* Guess if the receiver is using delayed ack. */
            int             dlyack_rx;
            /* Keep track of inconsistencies in packet timestamps. */
            int             timestamp_errors;
            /* RTT for a marked packet. */
            int             markedpkt_rtt;
            /* Flags to signal conditions between hook function calls. */
            uint32_t        flags;
    };
    
    /* Flags for struct ertt. */
    #define ERTT_NEW_MEASUREMENT            0x01
    #define ERTT_MEASUREMENT_IN_PROGRESS    0x02
    #define ERTT_TSO_DISABLED               0x04
    
    #endif /* _NETINET_KHELP_H_ERTT_ */

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