From 91fed7a15c9222af29a653ecb0ee72cff178fdd8 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Tue, 9 Oct 2007 01:24:15 -0700 Subject: [TCP]: Make fackets_out accurate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Substraction for fackets_out is unconditional when snd_una advances, thus there's no need to do it inside the loop. Just make sure correct bounds are honored. Signed-off-by: Ilpo Järvinen Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 44 ++++++++++++++++++++++++++------------------ 1 file changed, 26 insertions(+), 18 deletions(-) (limited to 'net/ipv4/tcp_output.c') diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 9df5b2a4da6e..cbe8bf6dab5f 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -652,6 +652,26 @@ static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned } } +/* When a modification to fackets out becomes necessary, we need to check + * skb is counted to fackets_out or not. Another important thing is to + * tweak SACK fastpath hint too as it would overwrite all changes unless + * hint is also changed. + */ +static void tcp_adjust_fackets_out(struct tcp_sock *tp, struct sk_buff *skb, + int decr) +{ + if (!tp->sacked_out) + return; + + if (!before(tp->highest_sack, TCP_SKB_CB(skb)->seq)) + tp->fackets_out -= decr; + + /* cnt_hint is "off-by-one" compared with fackets_out (see sacktag) */ + if (tp->fastpath_skb_hint != NULL && + after(TCP_SKB_CB(tp->fastpath_skb_hint)->seq, TCP_SKB_CB(skb)->seq)) + tp->fastpath_cnt_hint -= decr; +} + /* Function to create two new TCP segments. Shrinks the given segment * to the specified size and appends a new segment with the rest of the * packet to the list. This won't be called frequently, I hope. @@ -746,21 +766,12 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) tp->lost_out -= diff; - if (diff > 0) { - /* Adjust Reno SACK estimate. */ - if (tcp_is_reno(tp)) { - tcp_dec_pcount_approx_int(&tp->sacked_out, diff); - tcp_verify_left_out(tp); - } - - tcp_dec_pcount_approx_int(&tp->fackets_out, diff); - /* SACK fastpath might overwrite it unless dealt with */ - if (tp->fastpath_skb_hint != NULL && - after(TCP_SKB_CB(tp->fastpath_skb_hint)->seq, - TCP_SKB_CB(skb)->seq)) { - tcp_dec_pcount_approx_int(&tp->fastpath_cnt_hint, diff); - } + /* Adjust Reno SACK estimate. */ + if (tcp_is_reno(tp) && diff > 0) { + tcp_dec_pcount_approx_int(&tp->sacked_out, diff); + tcp_verify_left_out(tp); } + tcp_adjust_fackets_out(tp, skb, diff); } /* Link BUFF into the send queue. */ @@ -1746,10 +1757,7 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m if (tcp_is_reno(tp) && tp->sacked_out) tcp_dec_pcount_approx(&tp->sacked_out, next_skb); - /* Not quite right: it can be > snd.fack, but - * it is better to underestimate fackets. - */ - tcp_dec_pcount_approx(&tp->fackets_out, next_skb); + tcp_adjust_fackets_out(tp, skb, tcp_skb_pcount(next_skb)); tp->packets_out -= tcp_skb_pcount(next_skb); sk_stream_free_skb(sk, next_skb); } -- cgit v1.2.3