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[TCP]: Avoid clearing sacktag hint in trivial situations

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There's no reason to clear the sacktag skb hint when small part
of the rexmit queue changes. Account changes (if any) instead when
fragmenting/collapsing. RTO/FRTO do not touch SACKED_ACKED bits so
no need to discard SACK tag hint at all.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilpo Järvinen
2007-09-20 11:37:19 -07:00
committed by David S. Miller
parent c96fd3d461
commit b76892051c
3 changed files with 21 additions and 11 deletions
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12
net/ipv4/tcp_output.c
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@@ -687,7 +687,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
BUG_ON(len > skb->len);
tcp_clear_all_retrans_hints(tp);
tcp_clear_retrans_hints_partial(tp);
nsize = skb_headlen(skb) - len;
if (nsize < 0)
nsize = 0;
@@ -1718,9 +1718,6 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
BUG_ON(tcp_skb_pcount(skb) != 1 ||
tcp_skb_pcount(next_skb) != 1);
/* changing transmit queue under us so clear hints */
tcp_clear_all_retrans_hints(tp);
/* Ok. We will be able to collapse the packet. */
tcp_unlink_write_queue(next_skb, sk);
@@ -1759,6 +1756,13 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
tcp_adjust_fackets_out(tp, skb, tcp_skb_pcount(next_skb));
tp->packets_out -= tcp_skb_pcount(next_skb);
/* changed transmit queue under us so clear hints */
tcp_clear_retrans_hints_partial(tp);
/* manually tune sacktag skb hint */
if (tp->fastpath_skb_hint == next_skb)
tp->fastpath_skb_hint = skb;
sk_stream_free_skb(sk, next_skb);
}
}