From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuchung Cheng Subject: Re: [PATCH v6 net-next 2/2] tcp: Add Redundant Data Bundling (RDB) Date: Tue, 15 Mar 2016 11:09:18 -0700 Message-ID: References: <1457028388-18226-1-git-send-email-bro.devel+kernel@gmail.com> <1457028388-18226-3-git-send-email-bro.devel+kernel@gmail.com> <1457990140.31401.20.camel@edumazet-glaptop3.roam.corp.google.com> <56E75F8B.7090101@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Eric Dumazet , =?UTF-8?Q?Bendik_R=C3=B8nning_Opstad?= , "David S. Miller" , netdev , Neal Cardwell , Andreas Petlund , Carsten Griwodz , =?UTF-8?Q?P=C3=A5l_Halvorsen?= , Jonas Markussen , Kristian Evensen , Kenneth Klette Jonassen To: Rick Jones Return-path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:37235 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932212AbcCOSKA convert rfc822-to-8bit (ORCPT ); Tue, 15 Mar 2016 14:10:00 -0400 Received: by mail-wm0-f46.google.com with SMTP id p65so38683525wmp.0 for ; Tue, 15 Mar 2016 11:09:59 -0700 (PDT) In-Reply-To: <56E75F8B.7090101@hpe.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Mar 14, 2016 at 6:04 PM, Rick Jones wrote= : > > On 03/14/2016 02:15 PM, Eric Dumazet wrote: >> >> On Thu, 2016-03-03 at 19:06 +0100, Bendik R=C3=B8nning Opstad wrote: >>> >>> Redundant Data Bundling (RDB) is a mechanism for TCP aimed at reduc= ing >>> the latency for applications sending time-dependent data. >>> >>> Latency-sensitive applications or services, such as online games, >>> remote control systems, and VoIP, produce traffic with thin-stream >>> characteristics, characterized by small packets and relatively high >>> inter-transmission times (ITT). When experiencing packet loss, such >>> latency-sensitive applications are heavily penalized by the need to >>> retransmit lost packets, which increases the latency by a minimum o= f >>> one RTT for the lost packet. Packets coming after a lost packet are >>> held back due to head-of-line blocking, causing increased delays fo= r >>> all data segments until the lost packet has been retransmitted. >> >> >> Acked-by: Eric Dumazet >> >> Note that RDB probably should get some SNMP counters, >> so that we get an idea of how many times a loss could be repaired. > > > And some idea of the duplication seen by receivers, assuming there is= n't already a counter for such a thing in Linux. We sort of track that in the awkwardly named LINUX_MIB_DELAYEDACKLOST > > happy benchmarking, > > rick jones > > >> >> Ideally, if the path happens to be lossless, all these pro active >> bundles are overhead. Might be useful to make RDB conditional to >> tp->total_retrans or something. >> >> >