From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wout2-smtp.messagingengine.com (wout2-smtp.messagingengine.com [64.147.123.25]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 3038E3B2A4 for ; Sat, 7 Sep 2019 18:43:38 -0400 (EDT) Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.west.internal (Postfix) with ESMTP id 39B7A321 for ; Sat, 7 Sep 2019 18:43:37 -0400 (EDT) Received: from imap2 ([10.202.2.52]) by compute4.internal (MEProxy); Sat, 07 Sep 2019 18:43:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=althea.net; h= mime-version:message-id:date:from:to:subject:content-type; s= fm1; bh=gDwhozsak50E4sRdf5vkENblPKYK7LzOuFJ2gZU20Jc=; b=hzuuW8Uo dWzlWBHDqNp4NrIlXk64Bv6YgjKOfPsbV0XHNXfGjIG8w7jVijpUmy0KYlWf2SIe dmnhYFArJx9IpAX9fKAcONtGHwOsgNnW8E0d5+uJvDwxpdtCKiaXSUbTgIYQEDB/ bKmTYWByUHagwzLESo/EG5LPwvgdWIfPxUxxXdpdEaWVOxBlNmRvVQAZeB5oYiEm Rh1yQqtmEl39tCODSX5QKEBkRnDFwtSXM6ygFsPDTx0ImpE+oQHVpein3BMViKjV C9TUBO2S/+bUc61ChoyXI+Rq77tmfy4UVkSS/+5mcMdLzm8l4ztuNROVaN8hIo1T /W+BKatDWx8uBQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:date:from:message-id :mime-version:subject:to:x-me-proxy:x-me-proxy:x-me-sender :x-me-sender:x-sasl-enc; s=fm3; bh=gDwhozsak50E4sRdf5vkENblPKYK7 LzOuFJ2gZU20Jc=; b=WoAecH4IQiPOiQcHxq9i0zHY2AjwguBmHlxoxKpasEx/+ 7D8xcIn4uMaGC2+b65VB8UQDNpC3Z7nkcgFMs8fVtjxMxqIJOtqgqsq616VFj2cH dpzjVIj8uy4873Z/Oau2chuT1s110EpmAgknsjuqOwfLNvS5439PGFeeVF1UQGfE rcVK8BUbnZDVcqucOAr3GxB0atwUCe6X/PEUpVp9na3ryrDfTNmIwhYSNmC+MoQA TRbyGKUv5ezgUJz0nCYTUxT7BjMeRbfQntThh9k6elGHsmU5yvOU8r/o/okKt5y2 gGu8shdk0snzHTSCcTu+6F8bobqbsoxZfzPZ9qlhQ== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduvddrudekvddguddtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefofgggkfffhffvufgtsehttdertd erredtnecuhfhrohhmpedflfhushhtihhnucfmihhlphgrthhrihgtkhdfuceojhhushht ihhnsegrlhhthhgvrgdrnhgvtheqnecuffhomhgrihhnpeihohhuthhusggvrdgtohhmne curfgrrhgrmhepmhgrihhlfhhrohhmpehjuhhsthhinhesrghlthhhvggrrdhnvghtnecu vehluhhsthgvrhfuihiivgeptd X-ME-Proxy: Received: by mailuser.nyi.internal (Postfix, from userid 501) id 903B5E00A4; Sat, 7 Sep 2019 18:43:36 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.1.7-188-g385deb1-fmstable-20190905v2 Mime-Version: 1.0 Message-Id: Date: Sat, 07 Sep 2019 18:42:55 -0400 From: "Justin Kilpatrick" To: cake@lists.bufferbloat.net Content-Type: text/plain Subject: [Cake] Fighting bloat in the face of uncertinty X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 07 Sep 2019 22:43:38 -0000 I'm using Cake on embedded OpenWRT devices. You probably saw this video on the list a month or two ago. https://www.youtube.com/watch?v=G4EKbgShyLw Anyways up until now I've left cake totally untuned and had pretty great results. But we've finally encountered a scenario where untuned Cake allowed for unacceptable bufferbloat on a link. Hand configuration in accordance with the best practices provided in the RFC works out perfectly, but I need a set of settings I can ship with any device with the expectation that it will be used and abused in many non-standard situations. Producing non-optimal outcomes is fine, producing dramatically degraded outcomes is unacceptable. Which leads to a few questions 1) What happens if the target is dramatically too low? Most of our links can expect latency between 1-10ms, but they may occasionally go much longer than that. What are the consequences of having a 100ms link configured with a target of 10ms? 2) If interval is dramatically unpredictable is it best to err on the side of under or over estimating? The user may select an VPN/exit server of their own choosing, the path to it over the network may change or the exit may be much further away. Both 10ms and 80ms would be sane choices of target depending on factors that may change on the fly. Thanks for the feedback! -- Justin Kilpatrick justin@althea.net