From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753371AbbKBJiL (ORCPT ); Mon, 2 Nov 2015 04:38:11 -0500 Received: from smtp-out6.electric.net ([192.162.217.195]:55905 "EHLO smtp-out6.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750873AbbKBJiH (ORCPT ); Mon, 2 Nov 2015 04:38:07 -0500 From: David Laight To: =?utf-8?B?J0JlbmRpayBSw7hubmluZyBPcHN0YWQn?= , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Jonathan Corbet CC: Eric Dumazet , Neal Cardwell , Tom Herbert , Yuchung Cheng , "Paolo Abeni" , Erik Kline , Hannes Frederic Sowa , Al Viro , Jiri Pirko , Alexander Duyck , "Florian Westphal" , Daniel Lee , "Marcelo Ricardo Leitner" , Daniel Borkmann , "Willem de Bruijn" , =?utf-8?B?TGludXMgTMO8c3Npbmc=?= , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-api@vger.kernel.org" , Andreas Petlund , "Carsten Griwodz" , =?utf-8?B?UMOlbCBIYWx2b3JzZW4=?= , Jonas Markussen , Kristian Evensen , Kenneth Klette Jonassen , =?utf-8?B?QmVuZGlrIFLDuG5uaW5nIE9wc3RhZA==?= Subject: RE: [PATCH RFC net-next 2/2] tcp: Add Redundant Data Bundling (RDB) Thread-Topic: [PATCH RFC net-next 2/2] tcp: Add Redundant Data Bundling (RDB) Thread-Index: AQHRDdVXLHW12Ns+A0OejBNOpGG5QZ6Ig7gQ Date: Mon, 2 Nov 2015 09:37:54 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CBC86F1@AcuExch.aculab.com> References: <1445633413-3532-1-git-send-email-bro.devel+kernel@gmail.com> <1445633413-3532-3-git-send-email-bro.devel+kernel@gmail.com> In-Reply-To: <1445633413-3532-3-git-send-email-bro.devel+kernel@gmail.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.99.200] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 X-Outbound-IP: 213.249.233.130 X-Env-From: David.Laight@ACULAB.COM X-PolicySMART: 3396946, 3397078 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id tA29cFi1030401 From: Bendik Rønning Opstad > Sent: 23 October 2015 21:50 > RDB is a mechanism that enables a TCP sender to bundle redundant > (already sent) data with TCP packets containing new data. By bundling > (retransmitting) already sent data with each TCP packet containing new > data, the connection will be more resistant to sporadic packet loss > which reduces the application layer latency significantly in congested > scenarios. What sort of traffic flows do you expect this to help? An ssh (or similar) connection will get additional data to send, but that sort of data flow needs Nagle in order to reduce the number of packets sent. OTOH it might benefit from including unacked data if the Nagle timer expires. Being able to set the Nagle timer on a per-connection basis (or maybe using something based on the RTT instead of 2 secs) might make packet loss less problematic. Data flows that already have Nagle disabled (probably anything that isn't command-response and isn't unidirectional bulk data) are likely to generate a lot of packets within the RTT. Resending unacked data will just eat into available network bandwidth and could easily make any congestion worse. I think that means you shouldn't resend data more than once, and/or should make sure that the resent data isn't a significant overhead on the packet being sent. David {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Subject: RE: [PATCH RFC net-next 2/2] tcp: Add Redundant Data Bundling (RDB) Date: Mon, 2 Nov 2015 09:37:54 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CBC86F1@AcuExch.aculab.com> References: <1445633413-3532-1-git-send-email-bro.devel+kernel@gmail.com> <1445633413-3532-3-git-send-email-bro.devel+kernel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Cc: Eric Dumazet , Neal Cardwell , Tom Herbert , Yuchung Cheng , "Paolo Abeni" , Erik Kline , Hannes Frederic Sowa , Al Viro , Jiri Pirko , Alexander Duyck , "Florian Westphal" , Daniel Lee , "Marcelo Ricardo Leitner" , Daniel Borkmann , "Willem de Bruijn" , =?utf-8?B?TGludXMgTMO8c3Npbmc=?= , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-api@vger.kernel.org" , Andreas Petlund To: =?utf-8?B?J0JlbmRpayBSw7hubmluZyBPcHN0YWQn?= , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Jonathan Corbet Return-path: In-Reply-To: <1445633413-3532-3-git-send-email-bro.devel+kernel@gmail.com> Content-Language: en-US Sender: linux-doc-owner@vger.kernel.org List-Id: netdev.vger.kernel.org RnJvbTogQmVuZGlrIFLDuG5uaW5nIE9wc3RhZA0KPiBTZW50OiAyMyBPY3RvYmVyIDIwMTUgMjE6 NTANCj4gUkRCIGlzIGEgbWVjaGFuaXNtIHRoYXQgZW5hYmxlcyBhIFRDUCBzZW5kZXIgdG8gYnVu ZGxlIHJlZHVuZGFudA0KPiAoYWxyZWFkeSBzZW50KSBkYXRhIHdpdGggVENQIHBhY2tldHMgY29u dGFpbmluZyBuZXcgZGF0YS4gQnkgYnVuZGxpbmcNCj4gKHJldHJhbnNtaXR0aW5nKSBhbHJlYWR5 IHNlbnQgZGF0YSB3aXRoIGVhY2ggVENQIHBhY2tldCBjb250YWluaW5nIG5ldw0KPiBkYXRhLCB0 aGUgY29ubmVjdGlvbiB3aWxsIGJlIG1vcmUgcmVzaXN0YW50IHRvIHNwb3JhZGljIHBhY2tldCBs b3NzDQo+IHdoaWNoIHJlZHVjZXMgdGhlIGFwcGxpY2F0aW9uIGxheWVyIGxhdGVuY3kgc2lnbmlm aWNhbnRseSBpbiBjb25nZXN0ZWQNCj4gc2NlbmFyaW9zLg0KDQpXaGF0IHNvcnQgb2YgdHJhZmZp YyBmbG93cyBkbyB5b3UgZXhwZWN0IHRoaXMgdG8gaGVscD8NCg0KQW4gc3NoIChvciBzaW1pbGFy KSBjb25uZWN0aW9uIHdpbGwgZ2V0IGFkZGl0aW9uYWwgZGF0YSB0byBzZW5kLA0KYnV0IHRoYXQg c29ydCBvZiBkYXRhIGZsb3cgbmVlZHMgTmFnbGUgaW4gb3JkZXIgdG8gcmVkdWNlIHRoZQ0KbnVt YmVyIG9mIHBhY2tldHMgc2VudC4NCk9UT0ggaXQgbWlnaHQgYmVuZWZpdCBmcm9tIGluY2x1ZGlu ZyB1bmFja2VkIGRhdGEgaWYgdGhlIE5hZ2xlDQp0aW1lciBleHBpcmVzLg0KQmVpbmcgYWJsZSB0 byBzZXQgdGhlIE5hZ2xlIHRpbWVyIG9uIGEgcGVyLWNvbm5lY3Rpb24gYmFzaXMNCihvciBtYXli ZSB1c2luZyBzb21ldGhpbmcgYmFzZWQgb24gdGhlIFJUVCBpbnN0ZWFkIG9mIDIgc2VjcykNCm1p Z2h0IG1ha2UgcGFja2V0IGxvc3MgbGVzcyBwcm9ibGVtYXRpYy4NCg0KRGF0YSBmbG93cyB0aGF0 IGFscmVhZHkgaGF2ZSBOYWdsZSBkaXNhYmxlZCAocHJvYmFibHkgYW55dGhpbmcgdGhhdA0KaXNu J3QgY29tbWFuZC1yZXNwb25zZSBhbmQgaXNuJ3QgdW5pZGlyZWN0aW9uYWwgYnVsayBkYXRhKSBh cmUNCmxpa2VseSB0byBnZW5lcmF0ZSBhIGxvdCBvZiBwYWNrZXRzIHdpdGhpbiB0aGUgUlRULg0K UmVzZW5kaW5nIHVuYWNrZWQgZGF0YSB3aWxsIGp1c3QgZWF0IGludG8gYXZhaWxhYmxlIG5ldHdv cmsgYmFuZHdpZHRoDQphbmQgY291bGQgZWFzaWx5IG1ha2UgYW55IGNvbmdlc3Rpb24gd29yc2Uu DQoNCkkgdGhpbmsgdGhhdCBtZWFucyB5b3Ugc2hvdWxkbid0IHJlc2VuZCBkYXRhIG1vcmUgdGhh biBvbmNlLCBhbmQvb3INCnNob3VsZCBtYWtlIHN1cmUgdGhhdCB0aGUgcmVzZW50IGRhdGEgaXNu J3QgYSBzaWduaWZpY2FudCBvdmVyaGVhZA0Kb24gdGhlIHBhY2tldCBiZWluZyBzZW50Lg0KDQoJ RGF2aWQNCg0KDQo=