]> www.pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - net/ipv4/tcp_input.c
[TCP]: speed up SACK processing
[linux-2.6-omap-h63xx.git] / net / ipv4 / tcp_input.c
index 34cfa58eab7667ef3769bb63f0c3288b31b7e327..40a26b7157b49bcbf68530b37f14e80f4fa5c616 100644 (file)
@@ -897,18 +897,32 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
        int prior_fackets;
        u32 lost_retrans = 0;
        int flag = 0;
+       int dup_sack = 0;
        int i;
 
        if (!tp->sacked_out)
                tp->fackets_out = 0;
        prior_fackets = tp->fackets_out;
 
-       for (i=0; i<num_sacks; i++, sp++) {
-               struct sk_buff *skb;
-               __u32 start_seq = ntohl(sp->start_seq);
-               __u32 end_seq = ntohl(sp->end_seq);
-               int fack_count = 0;
-               int dup_sack = 0;
+       /* SACK fastpath:
+        * if the only SACK change is the increase of the end_seq of
+        * the first block then only apply that SACK block
+        * and use retrans queue hinting otherwise slowpath */
+       flag = 1;
+       for (i = 0; i< num_sacks; i++) {
+               __u32 start_seq = ntohl(sp[i].start_seq);
+               __u32 end_seq =  ntohl(sp[i].end_seq);
+
+               if (i == 0){
+                       if (tp->recv_sack_cache[i].start_seq != start_seq)
+                               flag = 0;
+               } else {
+                       if ((tp->recv_sack_cache[i].start_seq != start_seq) ||
+                           (tp->recv_sack_cache[i].end_seq != end_seq))
+                               flag = 0;
+               }
+               tp->recv_sack_cache[i].start_seq = start_seq;
+               tp->recv_sack_cache[i].end_seq = end_seq;
 
                /* Check for D-SACK. */
                if (i == 0) {
@@ -940,15 +954,58 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                        if (before(ack, prior_snd_una - tp->max_window))
                                return 0;
                }
+       }
+
+       if (flag)
+               num_sacks = 1;
+       else {
+               int j;
+               tp->fastpath_skb_hint = NULL;
+
+               /* order SACK blocks to allow in order walk of the retrans queue */
+               for (i = num_sacks-1; i > 0; i--) {
+                       for (j = 0; j < i; j++){
+                               if (after(ntohl(sp[j].start_seq),
+                                         ntohl(sp[j+1].start_seq))){
+                                       sp[j].start_seq = htonl(tp->recv_sack_cache[j+1].start_seq);
+                                       sp[j].end_seq = htonl(tp->recv_sack_cache[j+1].end_seq);
+                                       sp[j+1].start_seq = htonl(tp->recv_sack_cache[j].start_seq);
+                                       sp[j+1].end_seq = htonl(tp->recv_sack_cache[j].end_seq);
+                               }
+
+                       }
+               }
+       }
+
+       /* clear flag as used for different purpose in following code */
+       flag = 0;
+
+       for (i=0; i<num_sacks; i++, sp++) {
+               struct sk_buff *skb;
+               __u32 start_seq = ntohl(sp->start_seq);
+               __u32 end_seq = ntohl(sp->end_seq);
+               int fack_count;
+
+               /* Use SACK fastpath hint if valid */
+               if (tp->fastpath_skb_hint) {
+                       skb = tp->fastpath_skb_hint;
+                       fack_count = tp->fastpath_cnt_hint;
+               } else {
+                       skb = sk->sk_write_queue.next;
+                       fack_count = 0;
+               }
 
                /* Event "B" in the comment above. */
                if (after(end_seq, tp->high_seq))
                        flag |= FLAG_DATA_LOST;
 
-               sk_stream_for_retrans_queue(skb, sk) {
+               sk_stream_for_retrans_queue_from(skb, sk) {
                        int in_sack, pcount;
                        u8 sacked;
 
+                       tp->fastpath_skb_hint = skb;
+                       tp->fastpath_cnt_hint = fack_count;
+
                        /* The retransmission queue is always in order, so
                         * we can short-circuit the walk early.
                         */
@@ -1023,6 +1080,9 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                                                TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
                                                tp->lost_out -= tcp_skb_pcount(skb);
                                                tp->retrans_out -= tcp_skb_pcount(skb);
+
+                                               /* clear lost hint */
+                                               tp->retransmit_skb_hint = NULL;
                                        }
                                } else {
                                        /* New sack for not retransmitted frame,
@@ -1035,6 +1095,9 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                                        if (sacked & TCPCB_LOST) {
                                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
                                                tp->lost_out -= tcp_skb_pcount(skb);
+
+                                               /* clear lost hint */
+                                               tp->retransmit_skb_hint = NULL;
                                        }
                                }
 
@@ -1058,6 +1121,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                            (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS)) {
                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
                                tp->retrans_out -= tcp_skb_pcount(skb);
+                               tp->retransmit_skb_hint = NULL;
                        }
                }
        }
@@ -1085,6 +1149,9 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
                                tp->retrans_out -= tcp_skb_pcount(skb);
 
+                               /* clear lost hint */
+                               tp->retransmit_skb_hint = NULL;
+
                                if (!(TCP_SKB_CB(skb)->sacked&(TCPCB_LOST|TCPCB_SACKED_ACKED))) {
                                        tp->lost_out += tcp_skb_pcount(skb);
                                        TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
@@ -1192,6 +1259,8 @@ static void tcp_enter_frto_loss(struct sock *sk)
        tcp_set_ca_state(sk, TCP_CA_Loss);
        tp->high_seq = tp->frto_highmark;
        TCP_ECN_queue_cwr(tp);
+
+       clear_all_retrans_hints(tp);
 }
 
 void tcp_clear_retrans(struct tcp_sock *tp)
@@ -1258,6 +1327,8 @@ void tcp_enter_loss(struct sock *sk, int how)
        tcp_set_ca_state(sk, TCP_CA_Loss);
        tp->high_seq = tp->snd_nxt;
        TCP_ECN_queue_cwr(tp);
+
+       clear_all_retrans_hints(tp);
 }
 
 static int tcp_check_sack_reneging(struct sock *sk)
@@ -1482,17 +1553,37 @@ static void tcp_mark_head_lost(struct sock *sk, struct tcp_sock *tp,
                               int packets, u32 high_seq)
 {
        struct sk_buff *skb;
-       int cnt = packets;
+       int cnt;
 
-       BUG_TRAP(cnt <= tp->packets_out);
+       BUG_TRAP(packets <= tp->packets_out);
+       if (tp->lost_skb_hint) {
+               skb = tp->lost_skb_hint;
+               cnt = tp->lost_cnt_hint;
+       } else {
+               skb = sk->sk_write_queue.next;
+               cnt = 0;
+       }
 
-       sk_stream_for_retrans_queue(skb, sk) {
-               cnt -= tcp_skb_pcount(skb);
-               if (cnt < 0 || after(TCP_SKB_CB(skb)->end_seq, high_seq))
+       sk_stream_for_retrans_queue_from(skb, sk) {
+               /* TODO: do this better */
+               /* this is not the most efficient way to do this... */
+               tp->lost_skb_hint = skb;
+               tp->lost_cnt_hint = cnt;
+               cnt += tcp_skb_pcount(skb);
+               if (cnt > packets || after(TCP_SKB_CB(skb)->end_seq, high_seq))
                        break;
                if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
                        TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
                        tp->lost_out += tcp_skb_pcount(skb);
+
+                       /* clear xmit_retransmit_queue hints
+                        *  if this is beyond hint */
+                       if(tp->retransmit_skb_hint != NULL &&
+                          before(TCP_SKB_CB(skb)->seq,
+                                 TCP_SKB_CB(tp->retransmit_skb_hint)->seq)) {
+
+                               tp->retransmit_skb_hint = NULL;
+                       }
                }
        }
        tcp_sync_left_out(tp);
@@ -1519,13 +1610,28 @@ static void tcp_update_scoreboard(struct sock *sk, struct tcp_sock *tp)
        if (tcp_head_timedout(sk, tp)) {
                struct sk_buff *skb;
 
-               sk_stream_for_retrans_queue(skb, sk) {
-                       if (tcp_skb_timedout(sk, skb) &&
-                           !(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
+               skb = tp->scoreboard_skb_hint ? tp->scoreboard_skb_hint
+                       : sk->sk_write_queue.next;
+
+               sk_stream_for_retrans_queue_from(skb, sk) {
+                       if (!tcp_skb_timedout(sk, skb))
+                               break;
+
+                       if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
                                TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
                                tp->lost_out += tcp_skb_pcount(skb);
+
+                               /* clear xmit_retrans hint */
+                               if (tp->retransmit_skb_hint &&
+                                   before(TCP_SKB_CB(skb)->seq,
+                                          TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
+
+                                       tp->retransmit_skb_hint = NULL;
                        }
                }
+
+               tp->scoreboard_skb_hint = skb;
+
                tcp_sync_left_out(tp);
        }
 }
@@ -1605,6 +1711,10 @@ static void tcp_undo_cwr(struct sock *sk, const int undo)
        }
        tcp_moderate_cwnd(tp);
        tp->snd_cwnd_stamp = tcp_time_stamp;
+
+       /* There is something screwy going on with the retrans hints after
+          an undo */
+       clear_all_retrans_hints(tp);
 }
 
 static inline int tcp_may_undo(struct tcp_sock *tp)
@@ -1688,6 +1798,9 @@ static int tcp_try_undo_loss(struct sock *sk, struct tcp_sock *tp)
                sk_stream_for_retrans_queue(skb, sk) {
                        TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
                }
+
+               clear_all_retrans_hints(tp);
+
                DBGUNDO(sk, tp, "partial loss");
                tp->lost_out = 0;
                tp->left_out = tp->sacked_out;
@@ -2117,6 +2230,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
                tcp_packets_out_dec(tp, skb);
                __skb_unlink(skb, &sk->sk_write_queue);
                sk_stream_free_skb(sk, skb);
+               clear_all_retrans_hints(tp);
        }
 
        if (acked&FLAG_ACKED) {