From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp64.iad3b.emailsrvr.com (smtp64.iad3b.emailsrvr.com [146.20.161.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id AEFC83BA8E for ; Fri, 30 Nov 2018 06:53:37 -0500 (EST) Received: from smtp17.relay.iad3b.emailsrvr.com (localhost [127.0.0.1]) by smtp17.relay.iad3b.emailsrvr.com (SMTP Server) with ESMTP id 7DA10A0180; Fri, 30 Nov 2018 06:53:37 -0500 (EST) X-Auth-ID: jf@jonathanfoulkes.com Received: by smtp17.relay.iad3b.emailsrvr.com (Authenticated sender: jf-AT-jonathanfoulkes.com) with ESMTPSA id 3DD11A00E6; Fri, 30 Nov 2018 06:53:37 -0500 (EST) X-Sender-Id: jf@jonathanfoulkes.com Received: from JonsLaptop17 (h252.132.213.151.dynamic.ip.windstream.net [151.213.132.252]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384) by 0.0.0.0:465 (trex/5.7.12); Fri, 30 Nov 2018 06:53:37 -0500 From: To: "'Jonathan Morton'" , "'Luca Muscariello'" Cc: "'bloat'" References: <65EAC6C1-4688-46B6-A575-A6C7F2C066C5@heistp.net> <939858e1-eeff-01a3-fd35-fb3d2bbff6f8@kit.edu> In-Reply-To: Date: Fri, 30 Nov 2018 06:53:36 -0500 Message-ID: <00d801d488a3$545dfec0$fd19fc40$@jonathanfoulkes.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQKD5nGf/r8mFs25MfGh8q95L4uF2QF2tgJtAs6OtSoB2u8SgAGBOnq1AbMBaxQBDexDrgHy53RTAiCzuOwBb46t0QIoV1Ie Content-Language: en-us 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 11:53:37 -0000 >>If I can restate that in a more concrete way: the queue may not drain = at a smooth, constant rate. There are several real-world link = technologies which exhibit this behaviour - wifi and DOCSIS come to = mind, not to mention 3G/4G with variable signal strength. This! =20 Also, bottlenecks can move, such as when a DSLAMs backhaul reaches = saturation for minutes/hours in the evenings as everyone tries to = stream, and end-point connections drop to less than 50% of the local = sync-rate worth of effective capacity. Therefore AQM settings about link capacity should be thought of as a Max = not necessarily current link capacity. BTW- Amazing discussion, loving it. Jonathan Foulkes -----Original Message----- From: Bloat On Behalf Of Jonathan = Morton Sent: Friday, November 30, 2018 6:05 AM To: Luca Muscariello Cc: bloat Subject: Re: [Bloat] when does the CoDel part of fq_codel help in the = real world? > On 30 Nov, 2018, at 12:32 pm, Luca Muscariello = wrote: >=20 > Two last comments: one should always used fluid approximation with=20 > care, because they are approximations, the real model is more complex. = Nobody considers that the RTT varies during the connection lifetime and = that ACK can be delayed. > So CWD increases in a non simple way. If I can restate that in a more concrete way: the queue may not drain at = a smooth, constant rate. There are several real-world link technologies = which exhibit this behaviour - wifi and DOCSIS come to mind, not to = mention 3G/4G with variable signal strength. - Jonathan Morton _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat