From b253a0680ceadc5d7b4acca7aa2d870326cad8ad Mon Sep 17 00:00:00 2001 From: Pengcheng Yang Date: Wed, 20 Apr 2022 10:34:41 +0800 Subject: tcp: ensure to use the most recently sent skb when filling the rate sample If an ACK (s)acks multiple skbs, we favor the information from the most recently sent skb by choosing the skb with the highest prior_delivered count. But in the interval between receiving ACKs, we send multiple skbs with the same prior_delivered, because the tp->delivered only changes when we receive an ACK. We used RACK's solution, copying tcp_rack_sent_after() as tcp_skb_sent_after() helper to determine "which packet was sent last?". Later, we will use tcp_skb_sent_after() instead in RACK. Fixes: b9f64820fb22 ("tcp: track data delivery rate for a TCP connection") Signed-off-by: Pengcheng Yang Cc: Paolo Abeni Acked-by: Neal Cardwell Tested-by: Neal Cardwell Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/1650422081-22153-1-git-send-email-yangpc@wangsu.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_rate.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c index fbab921670cc..9a8e014d9b5b 100644 --- a/net/ipv4/tcp_rate.c +++ b/net/ipv4/tcp_rate.c @@ -74,27 +74,32 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb) * * If an ACK (s)acks multiple skbs (e.g., stretched-acks), this function is * called multiple times. We favor the information from the most recently - * sent skb, i.e., the skb with the highest prior_delivered count. + * sent skb, i.e., the skb with the most recently sent time and the highest + * sequence. */ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, struct rate_sample *rs) { struct tcp_sock *tp = tcp_sk(sk); struct tcp_skb_cb *scb = TCP_SKB_CB(skb); + u64 tx_tstamp; if (!scb->tx.delivered_mstamp) return; + tx_tstamp = tcp_skb_timestamp_us(skb); if (!rs->prior_delivered || - after(scb->tx.delivered, rs->prior_delivered)) { + tcp_skb_sent_after(tx_tstamp, tp->first_tx_mstamp, + scb->end_seq, rs->last_end_seq)) { rs->prior_delivered_ce = scb->tx.delivered_ce; rs->prior_delivered = scb->tx.delivered; rs->prior_mstamp = scb->tx.delivered_mstamp; rs->is_app_limited = scb->tx.is_app_limited; rs->is_retrans = scb->sacked & TCPCB_RETRANS; + rs->last_end_seq = scb->end_seq; /* Record send time of most recently ACKed packet: */ - tp->first_tx_mstamp = tcp_skb_timestamp_us(skb); + tp->first_tx_mstamp = tx_tstamp; /* Find the duration of the "send phase" of this window: */ rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp, scb->tx.first_tx_mstamp); -- cgit v1.2.3-73-gaa49b