[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, 15 insertions, 0 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 737b32e52956..0e1da6602e05 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -307,6 +307,21 @@ struct tcp_sock {
         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 
+        struct tcp_sack_block recv_sack_cache[4];
+
+        /* from STCP, retrans queue hinting */
+        struct sk_buff* lost_skb_hint;
+
+        struct sk_buff *scoreboard_skb_hint;
+        struct sk_buff *retransmit_skb_hint;
+        struct sk_buff *forward_skb_hint;
+        struct sk_buff *fastpath_skb_hint;
+
+        int     fastpath_cnt_hint;
+        int     lost_cnt_hint;
+        int     retransmit_cnt_hint;
+        int     forward_cnt_hint;
+
         __u16   advmss;         /* Advertised MSS                       */
         __u16   prior_ssthresh; /* ssthresh saved at recovery start     */
         __u32   lost_out;       /* Lost packets                 */