From patchwork Mon Aug 30 05:23:12 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gerrit Renker X-Patchwork-Id: 62997 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 7B573B70E9 for ; Mon, 30 Aug 2010 15:23:35 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754416Ab0H3FXb (ORCPT ); Mon, 30 Aug 2010 01:23:31 -0400 Received: from dee.erg.abdn.ac.uk ([139.133.204.82]:59461 "EHLO erg.abdn.ac.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754317Ab0H3FXa (ORCPT ); Mon, 30 Aug 2010 01:23:30 -0400 Received: from laptev.erg.abdn.ac.uk (Debian-exim@ra-gerrit.erg.abdn.ac.uk [139.133.204.38]) by erg.abdn.ac.uk (8.13.4/8.13.4) with ESMTP id o7U5NEMK008913 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 30 Aug 2010 06:23:14 +0100 (BST) Received: from root by laptev.erg.abdn.ac.uk with local (Exim 4.69) (envelope-from ) id 1Opwpu-0001TH-CH; Mon, 30 Aug 2010 07:23:14 +0200 From: Gerrit Renker To: davem@davemloft.net Cc: dccp@vger.kernel.org, netdev@vger.kernel.org, Gerrit Renker Subject: [PATCH 3/5] tcp/dccp: Consolidate common code for RFC 3390 conversion Date: Mon, 30 Aug 2010 07:23:12 +0200 Message-Id: <1283145794-5615-4-git-send-email-gerrit@erg.abdn.ac.uk> X-Mailer: git-send-email 1.6.0.rc2 In-Reply-To: <1283145794-5615-3-git-send-email-gerrit@erg.abdn.ac.uk> References: <1283145794-5615-1-git-send-email-gerrit@erg.abdn.ac.uk> <1283145794-5615-2-git-send-email-gerrit@erg.abdn.ac.uk> <1283145794-5615-3-git-send-email-gerrit@erg.abdn.ac.uk> X-ERG-MailScanner: Found to be clean X-ERG-MailScanner-From: root@erg.abdn.ac.uk X-Spam-Status: No Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch consolidates initial-window code common to TCP and CCID-2: * TCP uses RFC 3390 in a packet-oriented manner (tcp_input.c) and * CCID-2 uses RFC 3390 in packet-oriented manner (RFC 4341). Signed-off-by: Gerrit Renker --- include/net/tcp.h | 15 +++++++++++++++ net/dccp/ccids/ccid2.c | 8 ++------ net/ipv4/tcp_input.c | 17 ++--------------- 3 files changed, 19 insertions(+), 21 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -789,6 +789,21 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk) /* Use define here intentionally to get WARN_ON location shown at the caller */ #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) +/* + * Convert RFC 3390 larger initial window into an equivalent number of packets. + * + * John Heffner states: + * + * The RFC specifies a window of no more than 4380 bytes + * unless 2*MSS > 4380. Reading the pseudocode in the RFC + * is a bit misleading because they use a clamp at 4380 bytes + * rather than a multiplier in the relevant range. + */ +static inline u32 rfc3390_bytes_to_packets(const u32 smss) +{ + return smss <= 1095 ? 4 : (smss > 1460 ? 2 : 3); +} + extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh); extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst); --- a/net/dccp/ccids/ccid2.c +++ b/net/dccp/ccids/ccid2.c @@ -641,12 +641,8 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ hc->tx_ssthresh = ~0U; - /* - * RFC 4341, 5: "The cwnd parameter is initialized to at most four - * packets for new connections, following the rules from [RFC3390]". - * We need to convert the bytes of RFC3390 into the packets of RFC 4341. - */ - hc->tx_cwnd = clamp(4380U / dp->dccps_mss_cache, 2U, 4U); + /* Use larger initial windows (RFC 4341, section 5). */ + hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache); /* Make sure that Ack Ratio is enabled and within bounds. */ max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -805,25 +805,12 @@ void tcp_update_metrics(struct sock *sk) } } -/* Numbers are taken from RFC3390. - * - * John Heffner states: - * - * The RFC specifies a window of no more than 4380 bytes - * unless 2*MSS > 4380. Reading the pseudocode in the RFC - * is a bit misleading because they use a clamp at 4380 bytes - * rather than use a multiplier in the relevant range. - */ __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst) { __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); - if (!cwnd) { - if (tp->mss_cache > 1460) - cwnd = 2; - else - cwnd = (tp->mss_cache > 1095) ? 3 : 4; - } + if (!cwnd) + cwnd = rfc3390_bytes_to_packets(tp->mss_cache); return min_t(__u32, cwnd, tp->snd_cwnd_clamp); }