From a128e1c2f3d98794c7341f357628d1e7f737da23 Mon Sep 17 00:00:00 2001 From: Neal Cardwell Date: Sat, 5 Aug 2017 11:49:50 -0400 Subject: [PATCH 03/19] net-tcp_bbr: v2: snapshot packets in flight at transmit time and pass in rate_sample CC algorithms may want to snapshot the number of packets in flight at transmit time and pass in rate_sample, to understand the relationship between inflight and losses or ECN signals, to try to find the highest inflight value that has acceptable levels of loss/ECN marking. We split out the code to set an skb's tx.in_flight field into its own function, so that this code can be used for the TCP_REPAIR "fake send" code path that inserts skbs into the rtx queue without sending them. Effort: net-tcp_bbr Origin-9xx-SHA1: b3eb4f2d20efab4ca001f32c9294739036c493ea Origin-9xx-SHA1: e880fc907d06ea7354333f60f712748ebce9497b Origin-9xx-SHA1: 330f825a08a6fe92cef74d799cc468864c479f63 Change-Id: I7314047d0ff14dd261a04b1969a46dc658c8836a Signed-off-by: Alexandre Frade --- include/net/tcp.h | 6 ++++++ net/ipv4/tcp_output.c | 1 + net/ipv4/tcp_rate.c | 20 ++++++++++++++++++++ 3 files changed, 27 insertions(+) --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -998,6 +998,10 @@ struct tcp_skb_cb { u32 first_tx_mstamp; /* when we reached the "delivered" count */ u32 delivered_mstamp; +#define TCPCB_IN_FLIGHT_BITS 20 +#define TCPCB_IN_FLIGHT_MAX ((1U << TCPCB_IN_FLIGHT_BITS) - 1) + u32 in_flight:20, /* packets in flight at transmit */ + unused2:12; } tx; /* only used for outgoing skbs */ union { struct inet_skb_parm h4; @@ -1154,6 +1158,7 @@ struct rate_sample { u64 prior_mstamp; /* starting timestamp for interval */ u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */ + u32 tx_in_flight; /* packets in flight at starting timestamp */ s32 delivered; /* number of packets delivered over interval */ s32 delivered_ce; /* number of packets delivered w/ CE marks*/ long interval_us; /* time for tp->delivered to incr "delivered" */ @@ -1276,6 +1281,7 @@ static inline void tcp_ca_event(struct s void tcp_set_ca_state(struct sock *sk, const u8 ca_state); /* From tcp_rate.c */ +void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb); void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, struct rate_sample *rs); --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2770,6 +2770,7 @@ static bool tcp_write_xmit(struct sock * skb_set_delivery_time(skb, tp->tcp_wstamp_ns, SKB_CLOCK_MONOTONIC); list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); tcp_init_tso_segs(skb, mss_now); + tcp_set_tx_in_flight(sk, skb); goto repair; /* Skip network transmission */ } --- a/net/ipv4/tcp_rate.c +++ b/net/ipv4/tcp_rate.c @@ -34,6 +34,24 @@ * ready to send in the write queue. */ +void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb) +{ + struct tcp_sock *tp = tcp_sk(sk); + u32 in_flight; + + /* Check, sanitize, and record packets in flight after skb was sent. */ + in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb); + if (WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX, + "insane in_flight %u cc %s mss %u " + "cwnd %u pif %u %u %u %u\n", + in_flight, inet_csk(sk)->icsk_ca_ops->name, + tp->mss_cache, tp->snd_cwnd, + tp->packets_out, tp->retrans_out, + tp->sacked_out, tp->lost_out)) + in_flight = TCPCB_IN_FLIGHT_MAX; + TCP_SKB_CB(skb)->tx.in_flight = in_flight; +} + /* Snapshot the current delivery information in the skb, to generate * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered(). */ @@ -67,6 +85,7 @@ void tcp_rate_skb_sent(struct sock *sk, TCP_SKB_CB(skb)->tx.delivered = tp->delivered; TCP_SKB_CB(skb)->tx.delivered_ce = tp->delivered_ce; TCP_SKB_CB(skb)->tx.is_app_limited = tp->app_limited ? 1 : 0; + tcp_set_tx_in_flight(sk, skb); } /* When an skb is sacked or acked, we fill in the rate sample with the (prior) @@ -96,6 +115,7 @@ void tcp_rate_skb_delivered(struct sock rs->prior_mstamp = scb->tx.delivered_mstamp; rs->is_app_limited = scb->tx.is_app_limited; rs->is_retrans = scb->sacked & TCPCB_RETRANS; + rs->tx_in_flight = scb->tx.in_flight; rs->last_end_seq = scb->end_seq; /* Record send time of most recently ACKed packet: */