From 442b9635c569fef038d5367a7acd906db4677ae1 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 2 Feb 2011 17:05:11 -0800 Subject: tcp: Increase the initial congestion window to 10. Signed-off-by: David S. Miller Acked-by: Nandita Dukkipati --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eb7f82ebf4a3..2f692cefd3b0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -817,7 +817,7 @@ __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst) __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); if (!cwnd) - cwnd = rfc3390_bytes_to_packets(tp->mss_cache); + cwnd = TCP_INIT_CWND; return min_t(__u32, cwnd, tp->snd_cwnd_clamp); } -- cgit v1.2.3 From c24f691b56107feeba076616982093ee2d3c8fb5 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 7 Feb 2011 12:57:04 +0000 Subject: tcp: undo_retrans counter fixes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fix a bug that undo_retrans is incorrectly decremented when undo_marker is not set or undo_retrans is already 0. This happens when sender receives more DSACK ACKs than packets retransmitted during the current undo phase. This may also happen when sender receives DSACK after the undo operation is completed or cancelled. Fix another bug that undo_retrans is incorrectly incremented when sender retransmits an skb and tcp_skb_pcount(skb) > 1 (TSO). This case is rare but not impossible. Signed-off-by: Yuchung Cheng Acked-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 5 +++-- net/ipv4/tcp_output.c | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eb7f82ebf4a3..65f6c0406245 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1222,7 +1222,7 @@ static int tcp_check_dsack(struct sock *sk, struct sk_buff *ack_skb, } /* D-SACK for already forgotten data... Do dumb counting. */ - if (dup_sack && + if (dup_sack && tp->undo_marker && tp->undo_retrans && !after(end_seq_0, prior_snd_una) && after(end_seq_0, tp->undo_marker)) tp->undo_retrans--; @@ -1299,7 +1299,8 @@ static u8 tcp_sacktag_one(struct sk_buff *skb, struct sock *sk, /* Account D-SACK for retransmitted packet. */ if (dup_sack && (sacked & TCPCB_RETRANS)) { - if (after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker)) + if (tp->undo_marker && tp->undo_retrans && + after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker)) tp->undo_retrans--; if (sacked & TCPCB_SACKED_ACKED) state->reord = min(fack_count, state->reord); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 406f320336e6..dfa5beb0c1c8 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2162,7 +2162,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) if (!tp->retrans_stamp) tp->retrans_stamp = TCP_SKB_CB(skb)->when; - tp->undo_retrans++; + tp->undo_retrans += tcp_skb_pcount(skb); /* snd_nxt is stored to detect loss of retransmitted segment, * see tcp_input.c tcp_sacktag_write_queue(). -- cgit v1.2.3 From febf081987ec445f071ed10b73e9707a88cc5cc4 Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Mon, 14 Mar 2011 07:52:12 +0000 Subject: tcp: fix RTT for quick packets in congestion control In the congestion control interface, the callback for each ACK includes an estimated round trip time in microseconds. Some algorithms need high resolution (Vegas style) but most only need jiffie resolution. If RTT is not accurate (like a retransmission) -1 is used as a flag value. When doing coarse resolution if RTT is less than a a jiffie then 0 should be returned rather than no estimate. Otherwise algorithms that expect good ack's to trigger slow start (like CUBIC Hystart) will be confused. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 65f6c0406245..e16b17efcf57 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3350,7 +3350,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, net_invalid_timestamp())) rtt_us = ktime_us_delta(ktime_get_real(), last_ackt); - else if (ca_seq_rtt > 0) + else if (ca_seq_rtt >= 0) rtt_us = jiffies_to_usecs(ca_seq_rtt); } -- cgit v1.2.3 From 67d4120a1793138bc9f4a6eb61d0fc5298ed97e0 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 14 Mar 2011 10:57:03 +0000 Subject: tcp: avoid cwnd moderation in undo In the current undo logic, cwnd is moderated after it was restored to the value prior entering fast-recovery. It was moderated first in tcp_try_undo_recovery then again in tcp_complete_cwr. Since the undo indicates recovery was false, these moderations are not necessary. If the undo is triggered when most of the outstanding data have been acknowledged, the (restored) cwnd is falsely pulled down to a small value. This patch removes these cwnd moderations if cwnd is undone a) during fast-recovery b) by receiving DSACKs past fast-recovery Signed-off-by: Yuchung Cheng Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index da782e7ab16d..e72af7e31d1c 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2659,7 +2659,7 @@ static void DBGUNDO(struct sock *sk, const char *msg) #define DBGUNDO(x...) do { } while (0) #endif -static void tcp_undo_cwr(struct sock *sk, const int undo) +static void tcp_undo_cwr(struct sock *sk, const int undo_ssthresh) { struct tcp_sock *tp = tcp_sk(sk); @@ -2671,14 +2671,13 @@ static void tcp_undo_cwr(struct sock *sk, const int undo) else tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1); - if (undo && tp->prior_ssthresh > tp->snd_ssthresh) { + if (undo_ssthresh && tp->prior_ssthresh > tp->snd_ssthresh) { tp->snd_ssthresh = tp->prior_ssthresh; TCP_ECN_withdraw_cwr(tp); } } else { tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh); } - tcp_moderate_cwnd(tp); tp->snd_cwnd_stamp = tcp_time_stamp; } @@ -2822,8 +2821,11 @@ static int tcp_try_undo_loss(struct sock *sk) static inline void tcp_complete_cwr(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); - tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh); - tp->snd_cwnd_stamp = tcp_time_stamp; + /* Do not moderate cwnd if it's already undone in cwr or recovery */ + if (tp->undo_marker && tp->snd_cwnd > tp->snd_ssthresh) { + tp->snd_cwnd = tp->snd_ssthresh; + tp->snd_cwnd_stamp = tcp_time_stamp; + } tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR); } -- cgit v1.2.3 From f6152737a95bd6c22f0c664b20831aefd48085a8 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 22 Mar 2011 19:37:11 -0700 Subject: tcp: Make undo_ssthresh arg to tcp_undo_cwr() a bool. Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e72af7e31d1c..bef9f04c22ba 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2659,7 +2659,7 @@ static void DBGUNDO(struct sock *sk, const char *msg) #define DBGUNDO(x...) do { } while (0) #endif -static void tcp_undo_cwr(struct sock *sk, const int undo_ssthresh) +static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh) { struct tcp_sock *tp = tcp_sk(sk); @@ -2698,7 +2698,7 @@ static int tcp_try_undo_recovery(struct sock *sk) * or our original transmission succeeded. */ DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans"); - tcp_undo_cwr(sk, 1); + tcp_undo_cwr(sk, true); if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) mib_idx = LINUX_MIB_TCPLOSSUNDO; else @@ -2725,7 +2725,7 @@ static void tcp_try_undo_dsack(struct sock *sk) if (tp->undo_marker && !tp->undo_retrans) { DBGUNDO(sk, "D-SACK"); - tcp_undo_cwr(sk, 1); + tcp_undo_cwr(sk, true); tp->undo_marker = 0; NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO); } @@ -2778,7 +2778,7 @@ static int tcp_try_undo_partial(struct sock *sk, int acked) tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1); DBGUNDO(sk, "Hoe"); - tcp_undo_cwr(sk, 0); + tcp_undo_cwr(sk, false); NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO); /* So... Do not make Hoe's retransmit yet. @@ -2807,7 +2807,7 @@ static int tcp_try_undo_loss(struct sock *sk) DBGUNDO(sk, "partial loss"); tp->lost_out = 0; - tcp_undo_cwr(sk, 1); + tcp_undo_cwr(sk, true); NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO); inet_csk(sk)->icsk_retransmits = 0; tp->undo_marker = 0; @@ -3496,7 +3496,7 @@ static void tcp_undo_spur_to_response(struct sock *sk, int flag) if (flag & FLAG_ECE) tcp_ratehalving_spur_to_response(sk); else - tcp_undo_cwr(sk, 1); + tcp_undo_cwr(sk, true); } /* F-RTO spurious RTO detection algorithm (RFC4138) -- cgit v1.2.3