From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [RFC PATCH v2] tcp: TCP Small Queues Date: Thu, 12 Jul 2012 15:46:52 +0200 Message-ID: <1342100812.3265.8260.camel@edumazet-glaptop> References: <1340945457.29822.7.camel@edumazet-glaptop> <1341396687.2583.1757.camel@edumazet-glaptop> <20120709.000834.1182150057463599677.davem@davemloft.net> <1341845722.3265.3065.camel@edumazet-glaptop> <1341933215.3265.5476.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , ycheng@google.com, dave.taht@gmail.com, netdev@vger.kernel.org, codel@lists.bufferbloat.net, therbert@google.com, mattmathis@google.com, nanditad@google.com, ncardwell@google.com, andrewmcgr@gmail.com To: John Heffner Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:62302 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932480Ab2GLNq6 (ORCPT ); Thu, 12 Jul 2012 09:46:58 -0400 Received: by bkwj10 with SMTP id j10so2147787bkw.19 for ; Thu, 12 Jul 2012 06:46:56 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2012-07-12 at 09:33 -0400, John Heffner wrote: > One general question: why a per-connection limit? I haven't been > following the bufferbloat conversation closely so I may have missed > some of the conversation. But it seems that multiple connections will > still cause longer queue times. We already have a per-device limit, in qdisc. If you want to monitor several tcp sessions, I urge you use a controller for that. Like codel or fq_codel. Experiments show that limiting to two TSO packets in qdisc per tcp flow is enough to stop insane qdisc queueing, without impact on throughput for people wanting fast tcp sessions. Thats not solving the more general problem of having 1000 competing flows.