From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 2D90B3BA8E for ; Fri, 30 Nov 2018 14:58:22 -0500 (EST) Received: by mail-pg1-x52f.google.com with SMTP id y4so2925858pgc.12 for ; Fri, 30 Nov 2018 11:58:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=diJdqycI/RfWujOkhIVeRq2YvDZdpS5MnNd7swwBxFg=; b=SjztpmVDHuc6EvYA7x5by3fE4op4Vw8JZ6w5h3Rpa0v0mY6h2gLL8vTtRNf/iZEkPU Cg9e0NqXQNO4tVadlwBdGDa7iC+VrARZVlssMx9/qIqKuTTeFkdUPGtO70RG3yR0Tnwv bXsf9skzFmWlR5fQ8WgdeU4wv+u8XogC1WTAD4u1V+XdFIoqtiMwh4pM9Ays+aEGZVXk M/fDJoQfX8kSnCHpVzpCj79m58+Bl0C8aQkSHo3QDolq+JjGifgm6KyB1GRAj13/l4hp ETrrzHO3xMU+hIR+VP3ijTy+a6V2b6qVnCAjdij7pXz/c5Y+Jxqq0wcJa5xxuqj27+Ba JcxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=diJdqycI/RfWujOkhIVeRq2YvDZdpS5MnNd7swwBxFg=; b=eiKyCnU6PXCmFzNrjSalyi1wSZQW984DWm2J9nfqZdncnLUgrKr1LTSJNmbvLj/4+U vSUd416UjRFKJxXp56dl/odSX/oDKNZpWnedjF7m7NSvvB/x6nOLv9VtXshC8bcryTEu CaHMac8WvnnpdK2LRzh9YZXGM+afoFjLPZ1GmZO4XeJrvPLyI9QVXFPERUd/LxrRFnic 6UTFEh1dbofSfmJfLLVld6LUJXskgAY8y+RuG5dFLstHoRkLuRlauGFqD3SQj3bS0pSQ 2CvYTHi36uaxAbBLsdXVXuvrjt/l2981VyKwLvj/jWYgFYQE0Q764TrZsFjsZUfAPPLb If9A== X-Gm-Message-State: AA+aEWZDruwbOn8vDMux2JINR6Pl1DW4uH1vrlC8UgSzWZQnAjUQF9BR JqaFKlizkFQ+5r/Ks0MttWsFDg== X-Google-Smtp-Source: AFSGD/V6YpJJrwsVzIcq8+E+CwwJo+sODevLWOMia/F6S1E8S/XKiLcG/iPY+AMvXVgXdCihM4SXvw== X-Received: by 2002:a62:5a03:: with SMTP id o3mr6841678pfb.19.1543607901242; Fri, 30 Nov 2018 11:58:21 -0800 (PST) Received: from xeon-e3 (204-195-22-127.wavecable.com. [204.195.22.127]) by smtp.gmail.com with ESMTPSA id k129sm9632964pgk.29.2018.11.30.11.58.20 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 30 Nov 2018 11:58:21 -0800 (PST) Date: Fri, 30 Nov 2018 11:58:18 -0800 From: Stephen Hemminger To: Mikael Abrahamsson Cc: Dave Taht , Jonathan Morton , bloat Message-ID: <20181130115818.69697c77@xeon-e3> In-Reply-To: References: <65EAC6C1-4688-46B6-A575-A6C7F2C066C5@heistp.net> <86b16a95-e47d-896b-9d43-69c65c52afc7@kit.edu> <87d0qowd2e.fsf@taht.net> <20181129104332.5b2c7de7@xeon-e3> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] when does the CoDel part of fq_codel help in the real world? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Nov 2018 19:58:22 -0000 On Fri, 30 Nov 2018 06:51:34 +0100 (CET) Mikael Abrahamsson wrote: > On Thu, 29 Nov 2018, Stephen Hemminger wrote: > > > The problem is that any protocol is mostly blind to the underlying > > network (and that can change). To use dave's analogy it is like being > > put in the driver seat of a vehicle blind folded. When you step on the > > gas you don't know if it is a dragster, jet fighter, or a soviet > > tractor. The only way a protocol can tell is based on the perceived > > inertia and when it runs into things... > > Actually, I've made the argument to IETF TCPM that this is not true. You > can be able to communicate earlier data from previous flows on the same > connection so that new flows can re-learn this. > > If no flow the past hour has been able to run faster than 1 megabit/s and > always PMTUD to 1460 bytes MTU outbound, then there is good chance that > the next flow will encounter the same thing. Why not use this information > when guessing how things will behave going forward? > Since a majority of the flows in the world are coming from mobile, this both makes sense but is hard. Linux used to remember TCP metrics but this was removed with the flow cache.