/*
|
/*
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* H-TCP congestion control. The algorithm is detailed in:
|
* H-TCP congestion control. The algorithm is detailed in:
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* R.N.Shorten, D.J.Leith:
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* R.N.Shorten, D.J.Leith:
|
* "H-TCP: TCP for high-speed and long-distance networks"
|
* "H-TCP: TCP for high-speed and long-distance networks"
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* Proc. PFLDnet, Argonne, 2004.
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* Proc. PFLDnet, Argonne, 2004.
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* http://www.hamilton.ie/net/htcp3.pdf
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* http://www.hamilton.ie/net/htcp3.pdf
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*/
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*/
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|
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#include <linux/mm.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/module.h>
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#include <net/tcp.h>
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#include <net/tcp.h>
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|
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#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
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#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
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#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
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#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
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#define BETA_MAX 102 /* 0.8 with shift << 7 */
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#define BETA_MAX 102 /* 0.8 with shift << 7 */
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|
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static int use_rtt_scaling __read_mostly = 1;
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static int use_rtt_scaling __read_mostly = 1;
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module_param(use_rtt_scaling, int, 0644);
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module_param(use_rtt_scaling, int, 0644);
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MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
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MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
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|
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static int use_bandwidth_switch __read_mostly = 1;
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static int use_bandwidth_switch __read_mostly = 1;
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module_param(use_bandwidth_switch, int, 0644);
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module_param(use_bandwidth_switch, int, 0644);
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MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
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MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
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|
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struct htcp {
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struct htcp {
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u32 alpha; /* Fixed point arith, << 7 */
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u32 alpha; /* Fixed point arith, << 7 */
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u8 beta; /* Fixed point arith, << 7 */
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u8 beta; /* Fixed point arith, << 7 */
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u8 modeswitch; /* Delay modeswitch
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u8 modeswitch; /* Delay modeswitch
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until we had at least one congestion event */
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until we had at least one congestion event */
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u16 pkts_acked;
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u16 pkts_acked;
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u32 packetcount;
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u32 packetcount;
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u32 minRTT;
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u32 minRTT;
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u32 maxRTT;
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u32 maxRTT;
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u32 last_cong; /* Time since last congestion event end */
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u32 last_cong; /* Time since last congestion event end */
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u32 undo_last_cong;
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u32 undo_last_cong;
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|
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u32 undo_maxRTT;
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u32 undo_maxRTT;
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u32 undo_old_maxB;
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u32 undo_old_maxB;
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|
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/* Bandwidth estimation */
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/* Bandwidth estimation */
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u32 minB;
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u32 minB;
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u32 maxB;
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u32 maxB;
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u32 old_maxB;
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u32 old_maxB;
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u32 Bi;
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u32 Bi;
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u32 lasttime;
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u32 lasttime;
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};
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};
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static inline u32 htcp_cong_time(const struct htcp *ca)
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static inline u32 htcp_cong_time(const struct htcp *ca)
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{
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{
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return jiffies - ca->last_cong;
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return jiffies - ca->last_cong;
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}
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}
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static inline u32 htcp_ccount(const struct htcp *ca)
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static inline u32 htcp_ccount(const struct htcp *ca)
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{
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{
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return htcp_cong_time(ca) / ca->minRTT;
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return htcp_cong_time(ca) / ca->minRTT;
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}
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}
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static inline void htcp_reset(struct htcp *ca)
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static inline void htcp_reset(struct htcp *ca)
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{
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{
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ca->undo_last_cong = ca->last_cong;
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ca->undo_last_cong = ca->last_cong;
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ca->undo_maxRTT = ca->maxRTT;
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ca->undo_maxRTT = ca->maxRTT;
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ca->undo_old_maxB = ca->old_maxB;
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ca->undo_old_maxB = ca->old_maxB;
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|
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ca->last_cong = jiffies;
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ca->last_cong = jiffies;
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}
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}
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static u32 htcp_cwnd_undo(struct sock *sk)
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static u32 htcp_cwnd_undo(struct sock *sk)
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{
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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const struct tcp_sock *tp = tcp_sk(sk);
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struct htcp *ca = inet_csk_ca(sk);
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struct htcp *ca = inet_csk_ca(sk);
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ca->last_cong = ca->undo_last_cong;
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ca->last_cong = ca->undo_last_cong;
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ca->maxRTT = ca->undo_maxRTT;
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ca->maxRTT = ca->undo_maxRTT;
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ca->old_maxB = ca->undo_old_maxB;
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ca->old_maxB = ca->undo_old_maxB;
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|
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return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
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return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
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}
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}
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static inline void measure_rtt(struct sock *sk, u32 srtt)
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static inline void measure_rtt(struct sock *sk, u32 srtt)
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{
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{
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const struct inet_connection_sock *icsk = inet_csk(sk);
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const struct inet_connection_sock *icsk = inet_csk(sk);
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struct htcp *ca = inet_csk_ca(sk);
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struct htcp *ca = inet_csk_ca(sk);
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/* keep track of minimum RTT seen so far, minRTT is zero at first */
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/* keep track of minimum RTT seen so far, minRTT is zero at first */
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if (ca->minRTT > srtt || !ca->minRTT)
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if (ca->minRTT > srtt || !ca->minRTT)
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ca->minRTT = srtt;
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ca->minRTT = srtt;
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/* max RTT */
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/* max RTT */
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if (icsk->icsk_ca_state == TCP_CA_Open) {
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if (icsk->icsk_ca_state == TCP_CA_Open) {
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if (ca->maxRTT < ca->minRTT)
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if (ca->maxRTT < ca->minRTT)
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ca->maxRTT = ca->minRTT;
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ca->maxRTT = ca->minRTT;
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if (ca->maxRTT < srtt
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if (ca->maxRTT < srtt
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&& srtt <= ca->maxRTT + msecs_to_jiffies(20))
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&& srtt <= ca->maxRTT + msecs_to_jiffies(20))
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ca->maxRTT = srtt;
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ca->maxRTT = srtt;
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}
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}
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}
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}
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static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt)
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static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt)
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{
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{
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const struct inet_connection_sock *icsk = inet_csk(sk);
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const struct inet_connection_sock *icsk = inet_csk(sk);
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const struct tcp_sock *tp = tcp_sk(sk);
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const struct tcp_sock *tp = tcp_sk(sk);
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struct htcp *ca = inet_csk_ca(sk);
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struct htcp *ca = inet_csk_ca(sk);
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u32 now = tcp_time_stamp;
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u32 now = tcp_time_stamp;
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|
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if (icsk->icsk_ca_state == TCP_CA_Open)
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if (icsk->icsk_ca_state == TCP_CA_Open)
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ca->pkts_acked = pkts_acked;
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ca->pkts_acked = pkts_acked;
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|
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if (rtt > 0)
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if (rtt > 0)
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measure_rtt(sk, usecs_to_jiffies(rtt));
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measure_rtt(sk, usecs_to_jiffies(rtt));
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|
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if (!use_bandwidth_switch)
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if (!use_bandwidth_switch)
|
return;
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return;
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|
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/* achieved throughput calculations */
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/* achieved throughput calculations */
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if (icsk->icsk_ca_state != TCP_CA_Open &&
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if (icsk->icsk_ca_state != TCP_CA_Open &&
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icsk->icsk_ca_state != TCP_CA_Disorder) {
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icsk->icsk_ca_state != TCP_CA_Disorder) {
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ca->packetcount = 0;
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ca->packetcount = 0;
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ca->lasttime = now;
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ca->lasttime = now;
|
return;
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return;
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}
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}
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|
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ca->packetcount += pkts_acked;
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ca->packetcount += pkts_acked;
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|
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if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1)
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if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1)
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&& now - ca->lasttime >= ca->minRTT
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&& now - ca->lasttime >= ca->minRTT
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&& ca->minRTT > 0) {
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&& ca->minRTT > 0) {
|
__u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);
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__u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);
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|
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if (htcp_ccount(ca) <= 3) {
|
if (htcp_ccount(ca) <= 3) {
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/* just after backoff */
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/* just after backoff */
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ca->minB = ca->maxB = ca->Bi = cur_Bi;
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ca->minB = ca->maxB = ca->Bi = cur_Bi;
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} else {
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} else {
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ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
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ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
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if (ca->Bi > ca->maxB)
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if (ca->Bi > ca->maxB)
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ca->maxB = ca->Bi;
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ca->maxB = ca->Bi;
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if (ca->minB > ca->maxB)
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if (ca->minB > ca->maxB)
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ca->minB = ca->maxB;
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ca->minB = ca->maxB;
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}
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}
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ca->packetcount = 0;
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ca->packetcount = 0;
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ca->lasttime = now;
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ca->lasttime = now;
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}
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}
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}
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}
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static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
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static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
|
{
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{
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if (use_bandwidth_switch) {
|
if (use_bandwidth_switch) {
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u32 maxB = ca->maxB;
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u32 maxB = ca->maxB;
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u32 old_maxB = ca->old_maxB;
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u32 old_maxB = ca->old_maxB;
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ca->old_maxB = ca->maxB;
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ca->old_maxB = ca->maxB;
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|
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if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
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if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
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ca->beta = BETA_MIN;
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ca->beta = BETA_MIN;
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ca->modeswitch = 0;
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ca->modeswitch = 0;
|
return;
|
return;
|
}
|
}
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}
|
}
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|
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if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
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if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
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ca->beta = (minRTT << 7) / maxRTT;
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ca->beta = (minRTT << 7) / maxRTT;
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if (ca->beta < BETA_MIN)
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if (ca->beta < BETA_MIN)
|
ca->beta = BETA_MIN;
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ca->beta = BETA_MIN;
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else if (ca->beta > BETA_MAX)
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else if (ca->beta > BETA_MAX)
|
ca->beta = BETA_MAX;
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ca->beta = BETA_MAX;
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} else {
|
} else {
|
ca->beta = BETA_MIN;
|
ca->beta = BETA_MIN;
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ca->modeswitch = 1;
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ca->modeswitch = 1;
|
}
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}
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}
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}
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static inline void htcp_alpha_update(struct htcp *ca)
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static inline void htcp_alpha_update(struct htcp *ca)
|
{
|
{
|
u32 minRTT = ca->minRTT;
|
u32 minRTT = ca->minRTT;
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u32 factor = 1;
|
u32 factor = 1;
|
u32 diff = htcp_cong_time(ca);
|
u32 diff = htcp_cong_time(ca);
|
|
|
if (diff > HZ) {
|
if (diff > HZ) {
|
diff -= HZ;
|
diff -= HZ;
|
factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
|
factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
|
}
|
}
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|
|
if (use_rtt_scaling && minRTT) {
|
if (use_rtt_scaling && minRTT) {
|
u32 scale = (HZ << 3) / (10 * minRTT);
|
u32 scale = (HZ << 3) / (10 * minRTT);
|
|
|
/* clamping ratio to interval [0.5,10]<<3 */
|
/* clamping ratio to interval [0.5,10]<<3 */
|
scale = min(max(scale, 1U << 2), 10U << 3);
|
scale = min(max(scale, 1U << 2), 10U << 3);
|
factor = (factor << 3) / scale;
|
factor = (factor << 3) / scale;
|
if (!factor)
|
if (!factor)
|
factor = 1;
|
factor = 1;
|
}
|
}
|
|
|
ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
|
ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
|
if (!ca->alpha)
|
if (!ca->alpha)
|
ca->alpha = ALPHA_BASE;
|
ca->alpha = ALPHA_BASE;
|
}
|
}
|
|
|
/*
|
/*
|
* After we have the rtt data to calculate beta, we'd still prefer to wait one
|
* After we have the rtt data to calculate beta, we'd still prefer to wait one
|
* rtt before we adjust our beta to ensure we are working from a consistent
|
* rtt before we adjust our beta to ensure we are working from a consistent
|
* data.
|
* data.
|
*
|
*
|
* This function should be called when we hit a congestion event since only at
|
* This function should be called when we hit a congestion event since only at
|
* that point do we really have a real sense of maxRTT (the queues en route
|
* that point do we really have a real sense of maxRTT (the queues en route
|
* were getting just too full now).
|
* were getting just too full now).
|
*/
|
*/
|
static void htcp_param_update(struct sock *sk)
|
static void htcp_param_update(struct sock *sk)
|
{
|
{
|
struct htcp *ca = inet_csk_ca(sk);
|
struct htcp *ca = inet_csk_ca(sk);
|
u32 minRTT = ca->minRTT;
|
u32 minRTT = ca->minRTT;
|
u32 maxRTT = ca->maxRTT;
|
u32 maxRTT = ca->maxRTT;
|
|
|
htcp_beta_update(ca, minRTT, maxRTT);
|
htcp_beta_update(ca, minRTT, maxRTT);
|
htcp_alpha_update(ca);
|
htcp_alpha_update(ca);
|
|
|
/* add slowly fading memory for maxRTT to accommodate routing changes */
|
/* add slowly fading memory for maxRTT to accommodate routing changes */
|
if (minRTT > 0 && maxRTT > minRTT)
|
if (minRTT > 0 && maxRTT > minRTT)
|
ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
|
ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
|
}
|
}
|
|
|
static u32 htcp_recalc_ssthresh(struct sock *sk)
|
static u32 htcp_recalc_ssthresh(struct sock *sk)
|
{
|
{
|
const struct tcp_sock *tp = tcp_sk(sk);
|
const struct tcp_sock *tp = tcp_sk(sk);
|
const struct htcp *ca = inet_csk_ca(sk);
|
const struct htcp *ca = inet_csk_ca(sk);
|
|
|
htcp_param_update(sk);
|
htcp_param_update(sk);
|
return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
|
return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
|
}
|
}
|
|
|
static void htcp_cong_avoid(struct sock *sk, u32 ack,
|
static void htcp_cong_avoid(struct sock *sk, u32 ack,
|
u32 in_flight, int data_acked)
|
u32 in_flight, int data_acked)
|
{
|
{
|
struct tcp_sock *tp = tcp_sk(sk);
|
struct tcp_sock *tp = tcp_sk(sk);
|
struct htcp *ca = inet_csk_ca(sk);
|
struct htcp *ca = inet_csk_ca(sk);
|
|
|
if (!tcp_is_cwnd_limited(sk, in_flight))
|
if (!tcp_is_cwnd_limited(sk, in_flight))
|
return;
|
return;
|
|
|
if (tp->snd_cwnd <= tp->snd_ssthresh)
|
if (tp->snd_cwnd <= tp->snd_ssthresh)
|
tcp_slow_start(tp);
|
tcp_slow_start(tp);
|
else {
|
else {
|
/* In dangerous area, increase slowly.
|
/* In dangerous area, increase slowly.
|
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
|
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
|
*/
|
*/
|
if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
|
if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
|
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
|
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
|
tp->snd_cwnd++;
|
tp->snd_cwnd++;
|
tp->snd_cwnd_cnt = 0;
|
tp->snd_cwnd_cnt = 0;
|
htcp_alpha_update(ca);
|
htcp_alpha_update(ca);
|
} else
|
} else
|
tp->snd_cwnd_cnt += ca->pkts_acked;
|
tp->snd_cwnd_cnt += ca->pkts_acked;
|
|
|
ca->pkts_acked = 1;
|
ca->pkts_acked = 1;
|
}
|
}
|
}
|
}
|
|
|
static void htcp_init(struct sock *sk)
|
static void htcp_init(struct sock *sk)
|
{
|
{
|
struct htcp *ca = inet_csk_ca(sk);
|
struct htcp *ca = inet_csk_ca(sk);
|
|
|
memset(ca, 0, sizeof(struct htcp));
|
memset(ca, 0, sizeof(struct htcp));
|
ca->alpha = ALPHA_BASE;
|
ca->alpha = ALPHA_BASE;
|
ca->beta = BETA_MIN;
|
ca->beta = BETA_MIN;
|
ca->pkts_acked = 1;
|
ca->pkts_acked = 1;
|
ca->last_cong = jiffies;
|
ca->last_cong = jiffies;
|
}
|
}
|
|
|
static void htcp_state(struct sock *sk, u8 new_state)
|
static void htcp_state(struct sock *sk, u8 new_state)
|
{
|
{
|
switch (new_state) {
|
switch (new_state) {
|
case TCP_CA_Open:
|
case TCP_CA_Open:
|
{
|
{
|
struct htcp *ca = inet_csk_ca(sk);
|
struct htcp *ca = inet_csk_ca(sk);
|
ca->last_cong = jiffies;
|
ca->last_cong = jiffies;
|
}
|
}
|
break;
|
break;
|
case TCP_CA_CWR:
|
case TCP_CA_CWR:
|
case TCP_CA_Recovery:
|
case TCP_CA_Recovery:
|
case TCP_CA_Loss:
|
case TCP_CA_Loss:
|
htcp_reset(inet_csk_ca(sk));
|
htcp_reset(inet_csk_ca(sk));
|
break;
|
break;
|
}
|
}
|
}
|
}
|
|
|
static struct tcp_congestion_ops htcp = {
|
static struct tcp_congestion_ops htcp = {
|
.init = htcp_init,
|
.init = htcp_init,
|
.ssthresh = htcp_recalc_ssthresh,
|
.ssthresh = htcp_recalc_ssthresh,
|
.cong_avoid = htcp_cong_avoid,
|
.cong_avoid = htcp_cong_avoid,
|
.set_state = htcp_state,
|
.set_state = htcp_state,
|
.undo_cwnd = htcp_cwnd_undo,
|
.undo_cwnd = htcp_cwnd_undo,
|
.pkts_acked = measure_achieved_throughput,
|
.pkts_acked = measure_achieved_throughput,
|
.owner = THIS_MODULE,
|
.owner = THIS_MODULE,
|
.name = "htcp",
|
.name = "htcp",
|
};
|
};
|
|
|
static int __init htcp_register(void)
|
static int __init htcp_register(void)
|
{
|
{
|
BUILD_BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
|
BUILD_BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
|
BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
|
BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
|
return tcp_register_congestion_control(&htcp);
|
return tcp_register_congestion_control(&htcp);
|
}
|
}
|
|
|
static void __exit htcp_unregister(void)
|
static void __exit htcp_unregister(void)
|
{
|
{
|
tcp_unregister_congestion_control(&htcp);
|
tcp_unregister_congestion_control(&htcp);
|
}
|
}
|
|
|
module_init(htcp_register);
|
module_init(htcp_register);
|
module_exit(htcp_unregister);
|
module_exit(htcp_unregister);
|
|
|
MODULE_AUTHOR("Baruch Even");
|
MODULE_AUTHOR("Baruch Even");
|
MODULE_LICENSE("GPL");
|
MODULE_LICENSE("GPL");
|
MODULE_DESCRIPTION("H-TCP");
|
MODULE_DESCRIPTION("H-TCP");
|
|
|
