diff options
| -rw-r--r-- | include/linux/tcp.h | 6 | ||||
| -rw-r--r-- | include/net/tcp.h | 11 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 37 |
3 files changed, 35 insertions, 19 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index bc35e4709e8..a0513210798 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -197,7 +197,8 @@ struct tcp_sock { u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */ syn_data:1, /* SYN includes data */ syn_fastopen:1, /* SYN includes Fast Open option */ - syn_data_acked:1;/* data in SYN is acked by SYN-ACK */ + syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ + is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */ u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */ /* RTT measurement */ @@ -209,6 +210,8 @@ struct tcp_sock { u32 packets_out; /* Packets which are "in flight" */ u32 retrans_out; /* Retransmitted packets out */ + u32 max_packets_out; /* max packets_out in last window */ + u32 max_packets_seq; /* right edge of max_packets_out flight */ u16 urg_data; /* Saved octet of OOB data and control flags */ u8 ecn_flags; /* ECN status bits. */ @@ -230,7 +233,6 @@ struct tcp_sock { u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ u32 snd_cwnd_used; u32 snd_cwnd_stamp; - u32 lsnd_pending; /* packets inflight or unsent since last xmit */ u32 prior_cwnd; /* Congestion window at start of Recovery. */ u32 prr_delivered; /* Number of newly delivered packets to * receiver in Recovery. */ diff --git a/include/net/tcp.h b/include/net/tcp.h index f5d6ca4a9d2..e80abe4486c 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -971,8 +971,9 @@ static inline u32 tcp_wnd_end(const struct tcp_sock *tp) /* We follow the spirit of RFC2861 to validate cwnd but implement a more * flexible approach. The RFC suggests cwnd should not be raised unless - * it was fully used previously. But we allow cwnd to grow as long as the - * application has used half the cwnd. + * it was fully used previously. And that's exactly what we do in + * congestion avoidance mode. But in slow start we allow cwnd to grow + * as long as the application has used half the cwnd. * Example : * cwnd is 10 (IW10), but application sends 9 frames. * We allow cwnd to reach 18 when all frames are ACKed. @@ -985,7 +986,11 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); - return tp->snd_cwnd < 2 * tp->lsnd_pending; + /* If in slow start, ensure cwnd grows to twice what was ACKed. */ + if (tp->snd_cwnd <= tp->snd_ssthresh) + return tp->snd_cwnd < 2 * tp->max_packets_out; + + return tp->is_cwnd_limited; } static inline void tcp_check_probe_timer(struct sock *sk) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3d61c52bdf7..d463c35db33 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1402,11 +1402,19 @@ static void tcp_cwnd_application_limited(struct sock *sk) tp->snd_cwnd_stamp = tcp_time_stamp; } -static void tcp_cwnd_validate(struct sock *sk, u32 unsent_segs) +static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) { struct tcp_sock *tp = tcp_sk(sk); - tp->lsnd_pending = tp->packets_out + unsent_segs; + /* Track the maximum number of outstanding packets in each + * window, and remember whether we were cwnd-limited then. + */ + if (!before(tp->snd_una, tp->max_packets_seq) || + tp->packets_out > tp->max_packets_out) { + tp->max_packets_out = tp->packets_out; + tp->max_packets_seq = tp->snd_nxt; + tp->is_cwnd_limited = is_cwnd_limited; + } if (tcp_is_cwnd_limited(sk)) { /* Network is feed fully. */ @@ -1660,7 +1668,8 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, * * This algorithm is from John Heffner. */ -static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) +static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, + bool *is_cwnd_limited) { struct tcp_sock *tp = tcp_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); @@ -1724,6 +1733,9 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) if (!tp->tso_deferred) tp->tso_deferred = 1 | (jiffies << 1); + if (cong_win < send_win && cong_win < skb->len) + *is_cwnd_limited = true; + return true; send_now: @@ -1881,9 +1893,10 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, { struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; - unsigned int tso_segs, sent_pkts, unsent_segs = 0; + unsigned int tso_segs, sent_pkts; int cwnd_quota; int result; + bool is_cwnd_limited = false; sent_pkts = 0; @@ -1908,6 +1921,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, cwnd_quota = tcp_cwnd_test(tp, skb); if (!cwnd_quota) { + is_cwnd_limited = true; if (push_one == 2) /* Force out a loss probe pkt. */ cwnd_quota = 1; @@ -1924,8 +1938,9 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, nonagle : TCP_NAGLE_PUSH)))) break; } else { - if (!push_one && tcp_tso_should_defer(sk, skb)) - goto compute_unsent_segs; + if (!push_one && + tcp_tso_should_defer(sk, skb, &is_cwnd_limited)) + break; } /* TCP Small Queues : @@ -1950,14 +1965,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, * there is no smp_mb__after_set_bit() yet */ smp_mb__after_clear_bit(); - if (atomic_read(&sk->sk_wmem_alloc) > limit) { - u32 unsent_bytes; - -compute_unsent_segs: - unsent_bytes = tp->write_seq - tp->snd_nxt; - unsent_segs = DIV_ROUND_UP(unsent_bytes, mss_now); + if (atomic_read(&sk->sk_wmem_alloc) > limit) break; - } } limit = mss_now; @@ -1997,7 +2006,7 @@ repair: /* Send one loss probe per tail loss episode. */ if (push_one != 2) tcp_schedule_loss_probe(sk); - tcp_cwnd_validate(sk, unsent_segs); + tcp_cwnd_validate(sk, is_cwnd_limited); return false; } return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk)); |