[RFC PATCH v2 net-next 2/3] tcp: add in_flight to tcp_skb_cb
From: Lawrence Brakmo <hidden>
Date: 2015-07-22 04:21:43
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
Based on comments by Neal Cardwell to tcp_nv patch: AFAICT this patch would not require an increase in the size of sk_buff cb[] if it were to take advantage of the fact that the tcp_skb_cb header.h4 and header.h6 fields are only used in the packet reception code path, and this in_flight field is only used on the transmit side. So the in_flight field could be placed in a struct that is itself placed in a union with the "header" union. That way the sender code can remember the in_flight value without requiring any extra space. And in the future other sender-side info could be stored in the "tx" struct, if needed. Signed-off-by: Lawrence Brakmo <redacted> --- include/net/tcp.h | 13 ++++++++++--- net/ipv4/tcp_input.c | 5 ++++- net/ipv4/tcp_output.c | 4 +++- 3 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 26e7651..2e62efe 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h@@ -755,11 +755,17 @@ struct tcp_skb_cb { /* 1 byte hole */ __u32 ack_seq; /* Sequence number ACK'd */ union { - struct inet_skb_parm h4; + struct { + /* bytes in flight when this packet was sent */ + __u32 in_flight; + } tx; /* only used for outgoing skbs */ + union { + struct inet_skb_parm h4; #if IS_ENABLED(CONFIG_IPV6) - struct inet6_skb_parm h6; + struct inet6_skb_parm h6; #endif - } header; /* For incoming frames */ + } header; /* For incoming skbs */ + }; }; #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
@@ -837,6 +843,7 @@ union tcp_cc_info; struct ack_sample { u32 pkts_acked; s32 rtt_us; + u32 in_flight; }; struct tcp_congestion_ops {
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4f641f6..aca4ae5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c@@ -3068,6 +3068,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, long ca_rtt_us = -1L; struct sk_buff *skb; u32 pkts_acked = 0; + u32 last_in_flight = 0; bool rtt_update; int flag = 0;
@@ -3107,6 +3108,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, if (!first_ackt.v64) first_ackt = last_ackt; + last_in_flight = TCP_SKB_CB(skb)->tx.in_flight; reord = min(pkts_acked, reord); if (!after(scb->end_seq, tp->high_seq)) flag |= FLAG_ORIG_SACK_ACKED;
@@ -3196,7 +3198,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, } if (icsk->icsk_ca_ops->pkts_acked) { - struct ack_sample sample = {pkts_acked, ca_rtt_us}; + struct ack_sample sample = {pkts_acked, ca_rtt_us, + last_in_flight}; icsk->icsk_ca_ops->pkts_acked(sk, sample); }
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7105784..e9deab5 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c@@ -920,9 +920,12 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, int err; BUG_ON(!skb || !tcp_skb_pcount(skb)); + tp = tcp_sk(sk); if (clone_it) { skb_mstamp_get(&skb->skb_mstamp); + TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq + - tp->snd_una; if (unlikely(skb_cloned(skb))) skb = pskb_copy(skb, gfp_mask);
@@ -933,7 +936,6 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, } inet = inet_sk(sk); - tp = tcp_sk(sk); tcb = TCP_SKB_CB(skb); memset(&opts, 0, sizeof(opts));
--
1.8.1