From: Ilpo Järvinen Date: Sun, 21 Sep 2008 04:25:52 +0000 (-0700) Subject: tcp: don't clear lost_skb_hint when not necessary X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=90638a04ad8484b6b6c567656fb3f6d0689e23da;p=linux-beck.git tcp: don't clear lost_skb_hint when not necessary Most importantly avoid doing it with cumulative ACK. However, since we have lost_cnt_hint in the picture as well needing adjustments, it's not as trivial as dealing with retransmit_skb_hint (and cannot be done in the all place we could trivially leave retransmit_skb_hint untouched). With the previous patch, this should mostly remove O(n^2) behavior while cumulative ACKs start flowing once rexmit after a lossy round-trip made it through. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 44a4fffc2cc3..85627f83665f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2844,6 +2844,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets) int flag = 0; u32 pkts_acked = 0; u32 reord = tp->packets_out; + u32 prior_sacked = tp->sacked_out; s32 seq_rtt = -1; s32 ca_seq_rtt = -1; ktime_t last_ackt = net_invalid_timestamp(); @@ -2925,9 +2926,11 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets) tcp_unlink_write_queue(skb, sk); sk_wmem_free_skb(sk, skb); - tcp_clear_retrans_hints_partial(tp); + tp->scoreboard_skb_hint = NULL; if (skb == tp->retransmit_skb_hint) tp->retransmit_skb_hint = NULL; + if (skb == tp->lost_skb_hint) + tp->lost_skb_hint = NULL; } if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) @@ -2946,6 +2949,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets) /* Non-retransmitted hole got filled? That's reordering */ if (reord < prior_fackets) tcp_update_reordering(sk, tp->fackets_out - reord, 0); + + /* No need to care for underflows here because + * the lost_skb_hint gets NULLed if we're past it + * (or something non-trivial happened) + */ + if (tcp_is_fack(tp)) + tp->lost_cnt_hint -= pkts_acked; + else + tp->lost_cnt_hint -= prior_sacked - tp->sacked_out; } tp->fackets_out -= min(pkts_acked, tp->fackets_out);