[TCP]: speed up SACK processing

Use "hints" to speed up the SACK processing. Various forms 
of this have been used by TCP developers (Web100, STCP, BIC)
to avoid the 2x linear search of outstanding segments.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6e6f0f3f1dd8..0f9848011972 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1207,6 +1207,15 @@ static inline void tcp_mib_init(void)
         TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1);
 }
 
+/*from STCP */
+static inline void clear_all_retrans_hints(struct tcp_sock *tp){
+        tp->lost_skb_hint = NULL;
+        tp->scoreboard_skb_hint = NULL;
+        tp->retransmit_skb_hint = NULL;
+        tp->forward_skb_hint = NULL;
+        tp->fastpath_skb_hint = NULL;
+}
+
 /* /proc */
 enum tcp_seq_states {
         TCP_SEQ_STATE_LISTENING,