From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gavin McCullagh Subject: Re: [PATCH/RFC] [v2] TCP: use non-delayed ACK for congestion control RTT Date: Tue, 18 Dec 2007 20:40:22 +0000 Message-ID: <20071218204022.GA8936@nuim.ie> References: <20071217134425.GD7409@nuim.ie> Reply-To: Gavin McCullagh Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7BIT To: netdev@vger.kernel.org Return-path: Received: from banyan.nuim.ie ([149.157.1.4]:50721 "EHLO mango.nuim.ie" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752017AbXLRUkT (ORCPT ); Tue, 18 Dec 2007 15:40:19 -0500 Content-disposition: inline Received: from boing.hamilton.local ([149.157.192.252]) by mango.nuim.ie (Sun Java(tm) System Messaging Server 6.3-4.01 (built Aug 3 2007; 32bit)) with ESMTP id <0JT9007B7IR36S50@mango.nuim.ie> for netdev@vger.kernel.org; Tue, 18 Dec 2007 20:40:15 +0000 (GMT) In-reply-to: <20071217134425.GD7409@nuim.ie> Sender: netdev-owner@vger.kernel.org List-ID: The last attempt didn't take account of the situation where a timestamp wasn't available and tcp_clean_rtx_queue() has to feed both the RTO and the congestion avoidance. This updated patch stores both RTTs, making the delayed one available for the RTO and the other (ca_seq_rtt) available for congestion control. Signed-off-by: Gavin McCullagh diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 889c893..6fb7989 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2651,6 +2651,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p, u32 cnt = 0; u32 reord = tp->packets_out; s32 seq_rtt = -1; + s32 ca_seq_rtt = -1; ktime_t last_ackt = net_invalid_timestamp(); while ((skb = tcp_write_queue_head(sk)) && skb != tcp_send_head(sk)) { @@ -2686,13 +2687,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p, if (sacked & TCPCB_SACKED_RETRANS) tp->retrans_out -= packets_acked; flag |= FLAG_RETRANS_DATA_ACKED; + ca_seq_rtt = -1; seq_rtt = -1; if ((flag & FLAG_DATA_ACKED) || (packets_acked > 1)) flag |= FLAG_NONHEAD_RETRANS_ACKED; } else { + ca_seq_rtt = now - scb->when; if (seq_rtt < 0) { - seq_rtt = now - scb->when; + seq_rtt = ca_seq_rtt; if (fully_acked) last_ackt = skb->tstamp; } @@ -2709,8 +2712,9 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p, !before(end_seq, tp->snd_up)) tp->urg_mode = 0; } else { + ca_seq_rtt = now - scb->when; if (seq_rtt < 0) { - seq_rtt = now - scb->when; + seq_rtt = ca_seq_rtt; if (fully_acked) last_ackt = skb->tstamp; } @@ -2772,8 +2776,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p, net_invalid_timestamp())) rtt_us = ktime_us_delta(ktime_get_real(), last_ackt); - else if (seq_rtt > 0) - rtt_us = jiffies_to_usecs(seq_rtt); + else if (ca_seq_rtt > 0) + rtt_us = jiffies_to_usecs(ca_seq_rtt); } ca_ops->pkts_acked(sk, pkts_acked, rtt_us);