From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x232.google.com (mail-oi1-x232.google.com [IPv6:2607:f8b0:4864:20::232]) (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 4427B3B29D for ; Sat, 7 Dec 2024 17:25:48 -0500 (EST) Received: by mail-oi1-x232.google.com with SMTP id 5614622812f47-3eb31727984so342879b6e.0 for ; Sat, 07 Dec 2024 14:25:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1733610347; x=1734215147; darn=lists.bufferbloat.net; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=VYXyvgiR564U5g2awCmvfLvvD+k19dMRwhZQIESXp+U=; b=hLzYVDGQL/zb9TEMktPVIlveA+YHkSJJBpv2bTLMRzTuz3V1DStCHgNFcuUGnV8lE+ o/Cx8sbjwfnYBFQpWTQdY0V9/kLTyZlU11/7UPO/dAzcrgWXSffMV0D+fh6tET8zsEXx hsMBj7RRx393qy46MPTCdcxT+ae/LN0CDzyfNLTPVGzevfeuLyJfrI+AgAoh3r6YAjkb 6gIkKG+/b5Bzp9dxbdyM73XqdiSg6xhgzgVZ7EJfswsXG652rHUe9LaV7FV83dQORga5 8QJxj2id8gbngGjaKcF2o/1iYJHhWvZ+uuQ7gfcNX90fYQJzGw3XC3xB1etuHCOS4Vh1 ToAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733610347; x=1734215147; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VYXyvgiR564U5g2awCmvfLvvD+k19dMRwhZQIESXp+U=; b=nckdIVI7GiYvgzU1V7TxN6tqDmYoFzDxw36Pb+aVF6Dir76MifnDJYb7G5zNr/tpZX J/2MAuaPFWEJzlIBnE1ZzEE902XExX62iFqgvkJFHkuisLTY2cY2NJHtSvyYQjLTTPpH Lh7z5/KOXEd5Z38fYfFxk0NR1hAdD2fNEcJfQhpOY7WnUT0Kzwvr1z2JqV+4cytDcWuC H+xMxIgaBK7XJ7wS5jbfk09u+ya6Qj5bFggJ9NhkBedFwECkUtt2ybCYUWHSepyiLDOr wlSvu85KJvEVqTipdlpo9Zo90vVRslbAwgfeV275AzeKHfVq4gHzcUFsE4MYMWG4sX2G /H5A== X-Gm-Message-State: AOJu0YzudSCQIPExo4ZmhPHlLorONPPD2GfIL8NGxoHgBCiuUDuQDA1x oM7TjYxGoZwL4ndINFI+FVGJtwIZVMklPAr7lTfD5A6Ja5E+DdTj3yMn0V4D33llP8bQ+GxdZfB +n0o2m72ojRO7wjNsWPW1cR8MzEE= X-Gm-Gg: ASbGncsti7Ikrq4a8C15A9ePwxyqXllr8ERSPmd3YS9L7wTFfsdFCZqec3rQ7SHA5Bq NyC8KQt/XAKjO3t1HoGnySqW+w/umGmGiiCuF6Dp6cEHPmdPUECuNns9amMKOcqJ19Q== X-Google-Smtp-Source: AGHT+IFLgarpBM+MOHeKEpGY9xq6hVJbYkPiYq4JTfqoJcgulA8BtZ4tOJvulEgFWqf5BwlKoHkafLmi0rBOaM/qcsk= X-Received: by 2002:a05:6870:969f:b0:284:ff51:58ad with SMTP id 586e51a60fabf-29f738826a5mr5004027fac.27.1733610347538; Sat, 07 Dec 2024 14:25:47 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Sat, 7 Dec 2024 14:25:35 -0800 Message-ID: To: Evan Mesterhazy Cc: codel@lists.bufferbloat.net Content-Type: text/plain; charset="UTF-8" Subject: Re: [Codel] Do codel or fq-codel need to know the link bandwidth? X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 07 Dec 2024 22:25:48 -0000 Concurrent with the rise of codel was the bql algorithm in linux, and the combination of the two led to sufficient backpressure for it to operate at the native rate of the interface. (AQL does a similar job for wifi). This keeps queuing in the device ring down to what can be serviced in a single interrupt. "Bufferbloat Systematic Analysis": https://d1wqtxts1xzle7.cloudfront.net/109517412/its2014_bb-libre.pdf Byte queue limits: https://lwn.net/Articles/469652/ BSD has not evolved an equivalent mechanism. Theoretically you could run it natively but it would have a lot of jitter from a per-packet device ring. Further most ISPs use a non-native rate for their customer interfaces, either using a policer or FIFO shaper and thus the rise of combatting that with shaping via fq_codel to slightly below the ISPs' rate to move the bottleneck to your own hardware. We designed CAKE to use a deficit based shaper to be (roughly) the inverse of a token bucket shaper to get very close to the ISP rate yet shape well LibreQos (Preseem, Paraqum, Bequant) give ISPs a fq_codel or cake based shaper. The rightest answer was to have the isp correctly shape the download, and the uplink device shape the upload. The bufferbloat project has never had the resources to tackle BSD. These days all of Linux (and OSX) run fq_codel natively. The FIFO is dead.