Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763464AbXIXQmw (ORCPT ); Mon, 24 Sep 2007 12:42:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761210AbXIXQ2l (ORCPT ); Mon, 24 Sep 2007 12:28:41 -0400 Received: from canuck.infradead.org ([209.217.80.40]:58135 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761027AbXIXQ2k (ORCPT ); Mon, 24 Sep 2007 12:28:40 -0400 Date: Mon, 24 Sep 2007 09:22:41 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, bunk@kernel.org, Ilpo J?rvinen , "David S. Miller" Subject: [46/50] Fix TCP DSACK cwnd handling Message-ID: <20070924162241.GU13510@kroah.com> References: <20070924161246.983665021@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=unknown-8bit Content-Disposition: inline; filename="fix-tcp-dsack-cwnd-handling.patch" Content-Transfer-Encoding: 8bit In-Reply-To: <20070924161733.GA13510@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2174 Lines: 58 From: Ilpo J?rvinen commit 49ff4bb4cd4c04acf8f9e3d3ec2148305a1db445 in mainline. [TCP]: DSACK signals data receival, be conservative In case a DSACK is received, it's better to lower cwnd as it's a sign of data receival. Signed-off-by: Ilpo J?rvinen Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -103,6 +103,7 @@ int sysctl_tcp_abc __read_mostly; #define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/ #define FLAG_ONLY_ORIG_SACKED 0x200 /* SACKs only non-rexmit sent before RTO */ #define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */ +#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained DSACK info */ #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) #define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) @@ -966,12 +967,14 @@ tcp_sacktag_write_queue(struct sock *sk, /* Check for D-SACK. */ if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) { + flag |= FLAG_DSACKING_ACK; found_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))) { + flag |= FLAG_DSACKING_ACK; found_dup_sack = 1; tp->rx_opt.sack_ok |= 4; NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV); @@ -1858,7 +1861,7 @@ static void tcp_cwnd_down(struct sock *s struct tcp_sock *tp = tcp_sk(sk); int decr = tp->snd_cwnd_cnt + 1; - if ((flag&FLAG_ANY_PROGRESS) || + if ((flag&(FLAG_ANY_PROGRESS|FLAG_DSACKING_ACK)) || (IsReno(tp) && !(flag&FLAG_NOT_DUP))) { tp->snd_cwnd_cnt = decr&1; decr >>= 1; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/