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Date: Sat, 27 Jan 2007 18:49:49 +0200 From: Baruch Even <baruch@...en.org> To: "David S. Miller" <davem@...emloft.net> Cc: netdev@...r.kernel.org Subject: [PATCH 2/3] Seperate DSACK from SACK fast path Move DSACK code outside the SACK fast-path checking code. If the DSACK determined that the information was too old we stayed with a partial cache copied. Most likely this matters very little since the next packet will not be DSACK and we will find it in the cache. but it's still not good form and there is little reason to couple the two checks. Since the SACK receive cache doesn't need the data to be in host order we also remove the ntohl in the checking loop. Signed-Off-By: Baruch Even <baruch@...en.org> Index: 2.6-rc6/net/ipv4/tcp_input.c =================================================================== --- 2.6-rc6.orig/net/ipv4/tcp_input.c 2007-01-27 15:06:30.000000000 +0200 +++ 2.6-rc6/net/ipv4/tcp_input.c 2007-01-27 15:59:15.000000000 +0200 @@ -948,16 +948,43 @@ tp->fackets_out = 0; prior_fackets = tp->fackets_out; + /* Check for D-SACK. */ + if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) { + dup_sack = 1; + tp->rx_opt.sack_ok |= 4; + NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV); + } else if (num_sacks > 1 && + !after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) && + !before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) { + dup_sack = 1; + tp->rx_opt.sack_ok |= 4; + NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV); + } + + /* D-SACK for already forgotten data... + * Do dumb counting. */ + if (dup_sack && + !after(ntohl(sp[0].end_seq), prior_snd_una) && + after(ntohl(sp[0].end_seq), tp->undo_marker)) + tp->undo_retrans--; + + /* Eliminate too old ACKs, but take into + * account more or less fresh ones, they can + * contain valid SACK info. + */ + if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window)) + return 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); + for (i = 0; i < num_sacks; i++) { + __u32 start_seq = sp[i].start_seq; + __u32 end_seq = sp[i].end_seq; - if (i == 0){ + if (i == 0) { if (tp->recv_sack_cache[i].start_seq != start_seq) flag = 0; } else { @@ -967,37 +994,6 @@ } 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) { - u32 ack = TCP_SKB_CB(ack_skb)->ack_seq; - - if (before(start_seq, ack)) { - dup_sack = 1; - tp->rx_opt.sack_ok |= 4; - NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV); - } else if (num_sacks > 1 && - !after(end_seq, ntohl(sp[1].end_seq)) && - !before(start_seq, ntohl(sp[1].start_seq))) { - dup_sack = 1; - tp->rx_opt.sack_ok |= 4; - NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV); - } - - /* D-SACK for already forgotten data... - * Do dumb counting. */ - if (dup_sack && - !after(end_seq, prior_snd_una) && - after(end_seq, tp->undo_marker)) - tp->undo_retrans--; - - /* Eliminate too old ACKs, but take into - * account more or less fresh ones, they can - * contain valid SACK info. - */ - if (before(ack, prior_snd_una - tp->max_window)) - return 0; - } } if (flag) - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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