From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) (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 893353B29E for ; Fri, 8 May 2020 11:20:07 -0400 (EDT) Received: by mail-lf1-x12d.google.com with SMTP id h26so1714822lfg.6 for ; Fri, 08 May 2020 08:20:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=49ThPRfxnkQ5y9rYblKXdOUPzgGU1FKwkBfZekjaJx4=; b=QJSW2UD5VU9XChoaMNhVh/K5kofBSLlKVHAsurIgcUYe6/9DLZeLTXjtcpmAdf4MM4 SbHfaLY6aleiNChoP9QnFgTtEVwCLiZIoxkzsu3+67PLHxJgKX19VTALGII/WVo94mY+ +bJbx58ARt4lAScUj/T/t+paitLjqGW0OiRkznORQxpGvceywKo/5s8buDXVUbL1ighY Fht9B5qu+Gpu1qd+35OG+Zi1Nygprpd6nDY0KQRZP7blhVMGlyHaBEglKqaPiLpXtoJP 0fmLr/Q208MwgnCVmersDV1STG3xF1Rgy+h4iPgNWB5r/wcmINTsIplXCGS/P2dN6m5R IQ3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=49ThPRfxnkQ5y9rYblKXdOUPzgGU1FKwkBfZekjaJx4=; b=cAjvg3FPpgWq5MtHpSgA4YoxX1BwP0Z7UsUO0aVoH3koNP/HFvNz61oShsxl6SbgtH MxN9L6rinasAkOFDqJlvKg0ss63jWQYmexhG/Md3Uh/NefZEgFRULGyqA0s1JvWp5KWm 7cGkS1my04eG8dE0u3G88pDbyI3tfeoNVStqL+lrOOVYQTVXVDeinz6Wb8GWDGuQg5Au Zuiu1jV/ttgijrdY9XC+7mg9/xoUpDorSD/+nIou/xsO1LYFmzuKJPhKq0NiMLSc5Cwm W1VID8d+yWCKnIUR7y6iKT5QlYSBMrte+h9cwLLeWjF66HLe24xCLRdIgkOM5xiKUHQv ic2A== X-Gm-Message-State: AOAM530rf+IxP6ZARkHpNlpcMNbPJL0B3+BKBliA29KDB5yz72YoaG+w UPkZ7RhU8GGclh8hHvvEc2o= X-Google-Smtp-Source: ABdhPJwn3dlt6pngieUp9C/IPEVWMt+4Unsrihpnm1WfRfwJREErCXK6mv6HGTVH937pt13C7BqzLQ== X-Received: by 2002:a19:5518:: with SMTP id n24mr2283876lfe.61.1588951206369; Fri, 08 May 2020 08:20:06 -0700 (PDT) Received: from jonathartonsmbp.lan (83-245-235-192-nat-p.elisa-mobile.fi. [83.245.235.192]) by smtp.gmail.com with ESMTPSA id a11sm1436108lji.62.2020.05.08.08.20.04 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 May 2020 08:20:05 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: Date: Fri, 8 May 2020 18:20:03 +0300 Cc: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Avakash bhat , Vybhav Pai , Shrinidhi Varna , Cake List , "Mohit P. Tahiliani" , Deepak K Content-Transfer-Encoding: quoted-printable Message-Id: <7FCC9B1F-7F4B-43E8-B557-88B2A845C28B@gmail.com> References: <87wo5okhbo.fsf@toke.dk> <875zd6h3bu.fsf@toke.dk> To: Dave Taht X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Cake] Query on ACK 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: Fri, 08 May 2020 15:20:07 -0000 >> The ACK filter runs on enqueue, so if a queue has only ACKs in it, it >> will never accumulate anything in the first place... >=20 > but the side effect is that on dequeue, it flips it into the fast > queue drr rotation, not the slow, so it can't accumulate > as many acks before delivering the one it has left. >=20 > Or so I thought, way back when.... The ack filter converts a stream of acks that might be treated as a bulk = flow into a sparse flow, which is delivered promptly. This is a good = thing; an ack should not be held back solely to see whether another one = will arrive. I think of it as an optimisation to reduce delay of the information in = the ack stream, not solely as a way to reduce the bandwidth consumed by = the ack stream; the latter is a happy side effect. - Jonathan Morton=