From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (ipv6.swm.pp.se [IPv6:2a00:801::f]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 5EA203B29E for ; Fri, 30 Nov 2018 00:51:36 -0500 (EST) Received: by uplift.swm.pp.se (Postfix, from userid 501) id B0C53B1; Fri, 30 Nov 2018 06:51:34 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=swm.pp.se; s=mail; t=1543557094; bh=/TPR9pnOlA2lAtuOorilDaGkZu9+Hn5WOhStT67sTp0=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=1sInhcaW5gO1joKvKSLBJsEvAP4sRvpqKDafx/kROiyRcq1rw3bpbTr4SUvQr68ca zMbm3xOSZY1FWToTWx3Csla7mwRGbtXR9+5n7/LB0v2rkwm596uvqJQFKRAE1xnAgg c3qr9YzTVP3ANQA3GBTUrz7WEP+Upsb9JcjeZNiw= Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id AE6B5B0; Fri, 30 Nov 2018 06:51:34 +0100 (CET) Date: Fri, 30 Nov 2018 06:51:34 +0100 (CET) From: Mikael Abrahamsson To: Stephen Hemminger cc: Dave Taht , Jonathan Morton , bloat In-Reply-To: <20181129104332.5b2c7de7@xeon-e3> Message-ID: References: <65EAC6C1-4688-46B6-A575-A6C7F2C066C5@heistp.net> <86b16a95-e47d-896b-9d43-69c65c52afc7@kit.edu> <87d0qowd2e.fsf@taht.net> <20181129104332.5b2c7de7@xeon-e3> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed 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 05:51:36 -0000 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? -- Mikael Abrahamsson email: swmike@swm.pp.se