From 8a508ac26e72aa203677aa6a8464bd3ea44216a6 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 3 Dec 2006 14:50:23 -0200 Subject: [DCCP]: Use higher RTO default for CCID3 The TFRC nofeedback timer normally expires after the maximum of 4 RTTs and twice the current send interval (RFC 3448, 4.3). On LANs with a small RTT this can mean a high processing load and reduced performance, since then the nofeedback timer is triggered very frequently. This patch provides a configuration option to set the bound for the nofeedback timer, using as default 100 milliseconds. By setting the configuration option to 0, strict RFC 3448 behaviour can be enforced for the nofeedback timer. Signed-off-by: Gerrit Renker Signed-off-by: Arnaldo Carvalho de Melo --- net/dccp/ccids/Kconfig | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'net/dccp/ccids/Kconfig') diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig index dac89166eb1..80f46988769 100644 --- a/net/dccp/ccids/Kconfig +++ b/net/dccp/ccids/Kconfig @@ -89,4 +89,37 @@ config IP_DCCP_CCID3_DEBUG parameter to 0 or 1. If in doubt, say N. + +config IP_DCCP_CCID3_RTO + int "Use higher bound for nofeedback timer" + default 100 + depends on IP_DCCP_CCID3 && EXPERIMENTAL + ---help--- + Use higher lower bound for nofeedback timer expiration. + + The TFRC nofeedback timer normally expires after the maximum of 4 + RTTs and twice the current send interval (RFC 3448, 4.3). On LANs + with a small RTT this can mean a high processing load and reduced + performance, since then the nofeedback timer is triggered very + frequently. + + This option enables to set a higher lower bound for the nofeedback + value. Values in units of milliseconds can be set here. + + A value of 0 disables this feature by enforcing the value specified + in RFC 3448. The following values have been suggested as bounds for + experimental use: + * 16-20ms to match the typical multimedia inter-frame interval + * 100ms as a reasonable compromise [default] + * 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4) + + The default of 100ms is a compromise between a large value for + efficient DCCP implementations, and a small value to avoid disrupting + the network in times of congestion. + + The purpose of the nofeedback timer is to slow DCCP down when there + is serious network congestion: experimenting with larger values should + therefore not be performed on WANs. + + endmenu -- cgit v1.2.3