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d346d886a4
Add a check to prevent CCID-2 from increasing the cwnd greater than the Sequence Window. When the congestion window becomes bigger than the Sequence Window, CCID-2 will attempt to keep more data in the network than the DCCP Sequence Window code considers possible. This results in the Sequence Window code issuing a Sync, thereby inducing needless overhead. Further, if this occurs at the sender, CCID-2 will never detect the problem because the Acks it receives will indicate no losses. I have seen this cause a drop of 1/3rd in throughput for a connection. Also add code to adjust the Sequence Window to be about 5 times the number of packets in the network (RFC 4340, 7.5.2) and to adjust the Ack Ratio so that the remote Sequence Window will hold about 5 times the number of packets in the network. This allows the congestion window to increase correctly without being limited by the Sequence Window. Signed-off-by: Samuel Jero <sj323707@ohio.edu> Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
134 lines
3.9 KiB
C
134 lines
3.9 KiB
C
/*
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* Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef _DCCP_CCID2_H_
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#define _DCCP_CCID2_H_
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#include <linux/timer.h>
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#include <linux/types.h>
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#include "../ccid.h"
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#include "../dccp.h"
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/*
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* CCID-2 timestamping faces the same issues as TCP timestamping.
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* Hence we reuse/share as much of the code as possible.
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*/
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#define ccid2_time_stamp tcp_time_stamp
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/* NUMDUPACK parameter from RFC 4341, p. 6 */
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#define NUMDUPACK 3
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struct ccid2_seq {
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u64 ccid2s_seq;
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u32 ccid2s_sent;
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int ccid2s_acked;
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struct ccid2_seq *ccid2s_prev;
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struct ccid2_seq *ccid2s_next;
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};
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#define CCID2_SEQBUF_LEN 1024
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#define CCID2_SEQBUF_MAX 128
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/*
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* Multiple of congestion window to keep the sequence window at
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* (RFC 4340 7.5.2)
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*/
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#define CCID2_WIN_CHANGE_FACTOR 5
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/**
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* struct ccid2_hc_tx_sock - CCID2 TX half connection
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* @tx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5
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* @tx_packets_acked: Ack counter for deriving cwnd growth (RFC 3465)
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* @tx_srtt: smoothed RTT estimate, scaled by 2^3
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* @tx_mdev: smoothed RTT variation, scaled by 2^2
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* @tx_mdev_max: maximum of @mdev during one flight
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* @tx_rttvar: moving average/maximum of @mdev_max
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* @tx_rto: RTO value deriving from SRTT and RTTVAR (RFC 2988)
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* @tx_rtt_seq: to decay RTTVAR at most once per flight
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* @tx_cwnd_used: actually used cwnd, W_used of RFC 2861
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* @tx_expected_wnd: moving average of @tx_cwnd_used
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* @tx_cwnd_stamp: to track idle periods in CWV
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* @tx_lsndtime: last time (in jiffies) a data packet was sent
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* @tx_rpseq: last consecutive seqno
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* @tx_rpdupack: dupacks since rpseq
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* @tx_av_chunks: list of Ack Vectors received on current skb
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*/
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struct ccid2_hc_tx_sock {
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u32 tx_cwnd;
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u32 tx_ssthresh;
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u32 tx_pipe;
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u32 tx_packets_acked;
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struct ccid2_seq *tx_seqbuf[CCID2_SEQBUF_MAX];
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int tx_seqbufc;
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struct ccid2_seq *tx_seqh;
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struct ccid2_seq *tx_seqt;
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/* RTT measurement: variables/principles are the same as in TCP */
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u32 tx_srtt,
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tx_mdev,
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tx_mdev_max,
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tx_rttvar,
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tx_rto;
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u64 tx_rtt_seq:48;
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struct timer_list tx_rtotimer;
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/* Congestion Window validation (optional, RFC 2861) */
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u32 tx_cwnd_used,
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tx_expected_wnd,
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tx_cwnd_stamp,
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tx_lsndtime;
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u64 tx_rpseq;
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int tx_rpdupack;
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u32 tx_last_cong;
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u64 tx_high_ack;
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struct list_head tx_av_chunks;
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};
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static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc)
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{
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return hc->tx_pipe >= hc->tx_cwnd;
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}
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/*
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* Convert RFC 3390 larger initial window into an equivalent number of packets.
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* This is based on the numbers specified in RFC 5681, 3.1.
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*/
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static inline u32 rfc3390_bytes_to_packets(const u32 smss)
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{
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return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
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}
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/**
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* struct ccid2_hc_rx_sock - Receiving end of CCID-2 half-connection
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* @rx_num_data_pkts: number of data packets received since last feedback
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*/
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struct ccid2_hc_rx_sock {
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u32 rx_num_data_pkts;
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};
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static inline struct ccid2_hc_tx_sock *ccid2_hc_tx_sk(const struct sock *sk)
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{
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return ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
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}
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static inline struct ccid2_hc_rx_sock *ccid2_hc_rx_sk(const struct sock *sk)
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{
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return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
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}
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#endif /* _DCCP_CCID2_H_ */
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