From 50bf3e224a2963c6dd5098f77bd7233222ebfbd2 Mon Sep 17 00:00:00 2001 From: Baruch Even Date: Mon, 20 Mar 2006 22:23:10 -0800 Subject: [PATCH] [TCP] H-TCP: Better time accounting Instead of estimating the time since the last congestion event, count it directly. Signed-off-by: Baruch Even Signed-off-by: David S. Miller --- net/ipv4/tcp_htcp.c | 44 ++++++++++++++++++++++++++------------------ 1 file changed, 26 insertions(+), 18 deletions(-) diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c index ac19252e34..1b2ff53f98 100644 --- a/net/ipv4/tcp_htcp.c +++ b/net/ipv4/tcp_htcp.c @@ -27,13 +27,12 @@ struct htcp { u16 alpha; /* Fixed point arith, << 7 */ u8 beta; /* Fixed point arith, << 7 */ u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */ - u8 ccount; /* Number of RTTs since last congestion event */ - u8 undo_ccount; + u32 last_cong; /* Time since last congestion event end */ + u32 undo_last_cong; u16 pkts_acked; u32 packetcount; u32 minRTT; u32 maxRTT; - u32 snd_cwnd_cnt2; u32 undo_maxRTT; u32 undo_old_maxB; @@ -46,21 +45,30 @@ struct htcp { u32 lasttime; }; +static inline u32 htcp_cong_time(struct htcp *ca) +{ + return jiffies - ca->last_cong; +} + +static inline u32 htcp_ccount(struct htcp *ca) +{ + return htcp_cong_time(ca)/ca->minRTT; +} + static inline void htcp_reset(struct htcp *ca) { - ca->undo_ccount = ca->ccount; + ca->undo_last_cong = ca->last_cong; ca->undo_maxRTT = ca->maxRTT; ca->undo_old_maxB = ca->old_maxB; - ca->ccount = 0; - ca->snd_cwnd_cnt2 = 0; + ca->last_cong = jiffies; } static u32 htcp_cwnd_undo(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); struct htcp *ca = inet_csk_ca(sk); - ca->ccount = ca->undo_ccount; + ca->last_cong = ca->undo_last_cong; ca->maxRTT = ca->undo_maxRTT; ca->old_maxB = ca->undo_old_maxB; return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta); @@ -78,7 +86,7 @@ static inline void measure_rtt(struct sock *sk) ca->minRTT = srtt; /* max RTT */ - if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) { + if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) { if (ca->maxRTT < ca->minRTT) ca->maxRTT = ca->minRTT; if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20)) @@ -113,7 +121,7 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked) && now - ca->lasttime >= ca->minRTT && ca->minRTT > 0) { __u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime); - if (ca->ccount <= 3) { + if (htcp_ccount(ca) <= 3) { /* just after backoff */ ca->minB = ca->maxB = ca->Bi = cur_Bi; } else { @@ -158,7 +166,7 @@ static inline void htcp_alpha_update(struct htcp *ca) { u32 minRTT = ca->minRTT; u32 factor = 1; - u32 diff = ca->ccount * minRTT; /* time since last backoff */ + u32 diff = htcp_cong_time(ca); if (diff > HZ) { diff -= HZ; @@ -223,14 +231,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, measure_rtt(sk); - /* keep track of number of round-trip times since last backoff event */ - if (ca->snd_cwnd_cnt2 >= tp->snd_cwnd) { - ca->ccount++; - ca->snd_cwnd_cnt2 -= tp->snd_cwnd; - htcp_alpha_update(ca); - } else - ca->snd_cwnd_cnt2 += ca->pkts_acked; - /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd */ @@ -238,6 +238,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt, if (tp->snd_cwnd < tp->snd_cwnd_clamp) tp->snd_cwnd++; tp->snd_cwnd_cnt = 0; + htcp_alpha_update(ca); } else tp->snd_cwnd_cnt += ca->pkts_acked; @@ -261,11 +262,18 @@ static void htcp_init(struct sock *sk) ca->alpha = ALPHA_BASE; ca->beta = BETA_MIN; ca->pkts_acked = 1; + ca->last_cong = jiffies; } static void htcp_state(struct sock *sk, u8 new_state) { switch (new_state) { + case TCP_CA_Open: + { + struct htcp *ca = inet_csk_ca(sk); + ca->last_cong = jiffies; + } + break; case TCP_CA_CWR: case TCP_CA_Recovery: case TCP_CA_Loss: -- 2.39.5