From d61c167dd0797a16584f7a922dd5d50efad1d28a Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Mon, 27 Nov 2006 12:31:45 -0200 Subject: [NET]: Add documentation for TFRC structures This adds documentation for the TFRC structure fields. Signed-off-by: Gerrit Renker Signed-off-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/tfrc.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'include/linux/tfrc.h') diff --git a/include/linux/tfrc.h b/include/linux/tfrc.h index 7dab7831c3c..31a9b25276f 100644 --- a/include/linux/tfrc.h +++ b/include/linux/tfrc.h @@ -1,7 +1,8 @@ #ifndef _LINUX_TFRC_H_ #define _LINUX_TFRC_H_ /* - * include/linux/tfrc.h + * TFRC - Data Structures for the TCP-Friendly Rate Control congestion + * control mechanism as specified in RFC 3448. * * Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand. * Copyright (c) 2005 Ian McDonald @@ -13,15 +14,30 @@ * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ - #include +/** tfrc_rx_info - TFRC Receiver Data Structure + * + * @tfrcrx_x_recv: receiver estimate of sending rate (3.2.2) + * @tfrcrx_rtt: round-trip-time (communicated by sender) + * @tfrcrx_p: current estimate of loss event rate (3.2.2) + */ struct tfrc_rx_info { __u32 tfrcrx_x_recv; __u32 tfrcrx_rtt; __u32 tfrcrx_p; }; +/** tfrc_tx_info - TFRC Sender Data Structure + * + * @tfrctx_x: computed transmit rate (4.3 (4)) + * @tfrctx_x_recv: receiver estimate of send rate (4.3) + * @tfrctx_x_calc: return value of throughput equation (3.1) + * @tfrctx_rtt: (moving average) estimate of RTT (4.3) + * @tfrctx_p: current loss event rate (5.4) + * @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3) + * @tfrctx_ipi: inter-packet interval (4.6) + */ struct tfrc_tx_info { __u32 tfrctx_x; __u32 tfrctx_x_recv; -- cgit v1.2.3 From 1a21e49a8d60f588c1276f765198b14d5688a778 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 10 Dec 2006 00:02:12 -0200 Subject: [DCCP] ccid3: Finer-grained resolution of sending rates This patch * resolves a bug where packets smaller than 32/64 bytes resulted in sending rates of 0 * supports all sending rates from 1/64 bytes/second up to 4Gbyte/second * simplifies the present overflow problems in calculations Current sending rate X and the cached value X_recv of the receiver-estimated sending rate are both scaled by 64 (2^6) in order to * cope with low sending rates (minimally 1 byte/second) * allow upgrading to use a packets-per-second implementation of CCID 3 * avoid calculation errors due to integer arithmetic cut-off The patch implements a revised strategy from http://www.mail-archive.com/dccp@vger.kernel.org/msg01040.html The only difference with regard to that strategy is that t_ipi is already used in the calculation of the nofeedback timeout, which saves one division. Signed-off-by: Gerrit Renker Acked-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/tfrc.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include/linux/tfrc.h') diff --git a/include/linux/tfrc.h b/include/linux/tfrc.h index 31a9b25276f..8a8462b4a4d 100644 --- a/include/linux/tfrc.h +++ b/include/linux/tfrc.h @@ -37,10 +37,14 @@ struct tfrc_rx_info { * @tfrctx_p: current loss event rate (5.4) * @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3) * @tfrctx_ipi: inter-packet interval (4.6) + * + * Note: X and X_recv are both maintained in units of 64 * bytes/second. This + * enables a finer resolution of sending rates and avoids problems with + * integer arithmetic; u32 is not sufficient as scaling consumes 6 bits. */ struct tfrc_tx_info { - __u32 tfrctx_x; - __u32 tfrctx_x_recv; + __u64 tfrctx_x; + __u64 tfrctx_x_recv; __u32 tfrctx_x_calc; __u32 tfrctx_rtt; __u32 tfrctx_p; -- cgit v1.2.3