110 lines
4.4 KiB
Diff
110 lines
4.4 KiB
Diff
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From 25856231832186fe13189b986cc0e91860c18201 Mon Sep 17 00:00:00 2001
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From: Neal Cardwell <ncardwell@google.com>
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Date: Sat, 5 Aug 2017 11:49:50 -0400
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Subject: [PATCH 03/19] net-tcp_bbr: v2: snapshot packets in flight at transmit
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time and pass in rate_sample
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CC algorithms may want to snapshot the number of packets in flight at
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transmit time and pass in rate_sample, to understand the relationship
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between inflight and losses or ECN signals, to try to find the highest
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inflight value that has acceptable levels of loss/ECN marking.
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We split out the code to set an skb's tx.in_flight field into its own
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function, so that this code can be used for the TCP_REPAIR "fake send"
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code path that inserts skbs into the rtx queue without sending them.
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Effort: net-tcp_bbr
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Origin-9xx-SHA1: b3eb4f2d20efab4ca001f32c9294739036c493ea
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Origin-9xx-SHA1: e880fc907d06ea7354333f60f712748ebce9497b
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Origin-9xx-SHA1: 330f825a08a6fe92cef74d799cc468864c479f63
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Change-Id: I7314047d0ff14dd261a04b1969a46dc658c8836a
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Signed-off-by: Alexandre Frade <kernel@xanmod.org>
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---
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include/net/tcp.h | 6 ++++++
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net/ipv4/tcp_output.c | 1 +
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net/ipv4/tcp_rate.c | 20 ++++++++++++++++++++
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3 files changed, 27 insertions(+)
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--- a/include/net/tcp.h
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+++ b/include/net/tcp.h
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@@ -981,6 +981,10 @@ struct tcp_skb_cb {
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u32 first_tx_mstamp;
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/* when we reached the "delivered" count */
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u32 delivered_mstamp;
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+#define TCPCB_IN_FLIGHT_BITS 20
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+#define TCPCB_IN_FLIGHT_MAX ((1U << TCPCB_IN_FLIGHT_BITS) - 1)
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+ u32 in_flight:20, /* packets in flight at transmit */
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+ unused2:12;
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} tx; /* only used for outgoing skbs */
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union {
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struct inet_skb_parm h4;
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@@ -1136,6 +1140,7 @@ struct rate_sample {
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u64 prior_mstamp; /* starting timestamp for interval */
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u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
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u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
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+ u32 tx_in_flight; /* packets in flight at starting timestamp */
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s32 delivered; /* number of packets delivered over interval */
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s32 delivered_ce; /* number of packets delivered w/ CE marks*/
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long interval_us; /* time for tp->delivered to incr "delivered" */
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@@ -1258,6 +1263,7 @@ static inline void tcp_ca_event(struct s
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void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
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/* From tcp_rate.c */
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+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb);
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void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
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void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
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struct rate_sample *rs);
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -2765,6 +2765,7 @@ static bool tcp_write_xmit(struct sock *
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skb_set_delivery_time(skb, tp->tcp_wstamp_ns, SKB_CLOCK_MONOTONIC);
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list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
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tcp_init_tso_segs(skb, mss_now);
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+ tcp_set_tx_in_flight(sk, skb);
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goto repair; /* Skip network transmission */
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}
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--- a/net/ipv4/tcp_rate.c
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+++ b/net/ipv4/tcp_rate.c
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@@ -34,6 +34,24 @@
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* ready to send in the write queue.
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*/
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+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb)
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+{
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+ struct tcp_sock *tp = tcp_sk(sk);
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+ u32 in_flight;
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+
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+ /* Check, sanitize, and record packets in flight after skb was sent. */
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+ in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb);
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+ if (WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX,
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+ "insane in_flight %u cc %s mss %u "
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+ "cwnd %u pif %u %u %u %u\n",
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+ in_flight, inet_csk(sk)->icsk_ca_ops->name,
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+ tp->mss_cache, tp->snd_cwnd,
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+ tp->packets_out, tp->retrans_out,
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+ tp->sacked_out, tp->lost_out))
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+ in_flight = TCPCB_IN_FLIGHT_MAX;
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+ TCP_SKB_CB(skb)->tx.in_flight = in_flight;
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+}
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+
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/* Snapshot the current delivery information in the skb, to generate
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* a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
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*/
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@@ -67,6 +85,7 @@ void tcp_rate_skb_sent(struct sock *sk,
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TCP_SKB_CB(skb)->tx.delivered = tp->delivered;
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TCP_SKB_CB(skb)->tx.delivered_ce = tp->delivered_ce;
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TCP_SKB_CB(skb)->tx.is_app_limited = tp->app_limited ? 1 : 0;
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+ tcp_set_tx_in_flight(sk, skb);
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}
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/* When an skb is sacked or acked, we fill in the rate sample with the (prior)
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@@ -96,6 +115,7 @@ void tcp_rate_skb_delivered(struct sock
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rs->prior_mstamp = scb->tx.delivered_mstamp;
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rs->is_app_limited = scb->tx.is_app_limited;
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rs->is_retrans = scb->sacked & TCPCB_RETRANS;
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+ rs->tx_in_flight = scb->tx.in_flight;
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rs->last_end_seq = scb->end_seq;
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/* Record send time of most recently ACKed packet: */
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