From e8c17561fd4afb5966cb8e434375c26dd80e876b Mon Sep 17 00:00:00 2001 From: Neal Cardwell Date: Mon, 21 Sep 2020 14:46:26 -0400 Subject: [PATCH 14/19] net-tcp_bbr: v2: introduce is_acking_tlp_retrans_seq into rate_sample Introduce is_acking_tlp_retrans_seq into rate_sample. This bool will export to the CC module the knowledge of whether the current ACK matched a TLP retransmit. Note that when this bool is true, we cannot yet tell (in general) whether this ACK is for the original or the TLP retransmit. Effort: net-tcp_bbr Change-Id: I2e6494332167e75efcbdc99bd5c119034e9c39b4 Signed-off-by: Alexandre Frade --- include/net/tcp.h | 1 + net/ipv4/tcp_input.c | 12 +++++++++--- 2 files changed, 10 insertions(+), 3 deletions(-) --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1179,6 +1179,7 @@ struct rate_sample { u32 last_end_seq; /* end_seq of most recently ACKed packet */ bool is_app_limited; /* is sample from packet with bubble in pipe? */ bool is_retrans; /* is sample from retransmission? */ + bool is_acking_tlp_retrans_seq; /* ACKed a TLP retransmit sequence? */ bool is_ack_delayed; /* is this (likely) a delayed ACK? */ bool is_ece; /* did this ACK have ECN marked? */ }; --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3862,7 +3862,8 @@ static void tcp_replace_ts_recent(struct /* This routine deals with acks during a TLP episode and ends an episode by * resetting tlp_high_seq. Ref: TLP algorithm in draft-ietf-tcpm-rack */ -static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) +static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag, + struct rate_sample *rs) { struct tcp_sock *tp = tcp_sk(sk); @@ -3890,6 +3891,11 @@ static void tcp_process_tlp_ack(struct s FLAG_NOT_DUP | FLAG_DATA_SACKED))) { /* Pure dupack: original and TLP probe arrived; no loss */ tp->tlp_high_seq = 0; + } else { + /* This ACK matches a TLP retransmit. We cannot yet tell if + * this ACK is for the original or the TLP retransmit. + */ + rs->is_acking_tlp_retrans_seq = 1; } } @@ -4075,7 +4081,7 @@ static int tcp_ack(struct sock *sk, cons tcp_in_ack_event(sk, flag); if (tp->tlp_high_seq) - tcp_process_tlp_ack(sk, ack, flag); + tcp_process_tlp_ack(sk, ack, flag, &rs); if (tcp_ack_is_dubious(sk, flag)) { if (!(flag & (FLAG_SND_UNA_ADVANCED | @@ -4120,7 +4126,7 @@ no_queue: tcp_ack_probe(sk); if (tp->tlp_high_seq) - tcp_process_tlp_ack(sk, ack, flag); + tcp_process_tlp_ack(sk, ack, flag, &rs); return 1; old_ack: