From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [IPv6:2a00:1450:4864:20::22e]) (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 0B0B23B29D for ; Thu, 7 May 2020 02:59:54 -0400 (EDT) Received: by mail-lj1-x22e.google.com with SMTP id u15so5113857ljd.3 for ; Wed, 06 May 2020 23:59:53 -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=lj4rnQoW3rZbq8EDSJNMJsmipyZkr4CR6fe8VvvhNxg=; b=nJA5tNd4ZpT2/sngk9zIeg1K19bgfJrrUxGtCOavaM0BzgLbXyWvMgU2oKkHNJznaL XhISnP18E1CKXYwh995JSl42j+1+Wu0oIbsaIwFUPQNXm8i+SVfEaJ5UuUL14r0u7Geo gUMFMFYyCzgviEq0RPpRyYImoiV06Lx2sOG1jn8o0HV9BqwALDx+bMNmCFhF838zRl4T dvqrr+SfOqfk3syM9QJkw0W9gXXhJ6fAGiFx2AUUepJQd+at0Pp3wZdGGvMtpaTq9/ux GXfpMIZwSDboB7HGfz6AfYvy+g7cAdeR0t/U2hA/eaLOPr3MzjrYAnC/M28upyyBScMU G3Uw== 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=lj4rnQoW3rZbq8EDSJNMJsmipyZkr4CR6fe8VvvhNxg=; b=fVyaVN5QWOT0pjuIcQ5yQYYve2YplCSZydS1RYFD9jtnZ3NhyWydW8sokN95ONlEfo 2dXNVaYq22fyiKc988ggXxNaCBf5gPfh/tsKlUWffnauTOJaGHn3ARIRvfbaBrOaS7IN tjWZugWU25sw0JbjhFv4UtPHooVaSJartZ3bGPBJLWCf6YnLteM0ni7Oazh+o1HVje2/ BvE6ikq2sB1+hfm3VELHrhVVHEclfgSVIAno8erthUSBjvVBBPFGcZDdHikTzK1F5lxj 5mNYzumcTCFOAMXC2qhCumbJwf1nO5eR2R3sxiHgV8sohlIToLKQ4es9YGP5oFY5sAHF N8pw== X-Gm-Message-State: AGi0PuZijmqw1xhmK6Yvj/lCBxj3oJJtSbjBRUYKN4/oYl0caw2IHWcJ h+DtzST2E2LFHAFjH3cfiCg= X-Google-Smtp-Source: APiQypJhbb3c1vkazDsFAODVwOzoDaBR15fPe29P8uZNtPp+XC+nYrPNU3yOypQAn4Wh+ZZvyAu80Q== X-Received: by 2002:a2e:8590:: with SMTP id b16mr7755279lji.45.1588834792877; Wed, 06 May 2020 23:59:52 -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 g1sm3111399lfb.85.2020.05.06.23.59.51 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 May 2020 23:59:51 -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: Thu, 7 May 2020 09:59:49 +0300 Cc: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , cake@lists.bufferbloat.net, "Mohit P. Tahiliani" , Vybhav Pai , Deepak K , Shrinidhi Varna Content-Transfer-Encoding: quoted-printable Message-Id: <8258F6F9-0754-49C7-BEEE-92AE7A944B1A@gmail.com> References: <87wo5okhbo.fsf@toke.dk> To: Avakash bhat 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: Thu, 07 May 2020 06:59:54 -0000 > On 7 May, 2020, at 9:44 am, Avakash bhat wrote: >=20 > Thanks for the quick response. I also had a followup question.=20 >=20 > If the ack filter adds the new ack to the tail of the queue after = removing an ack from the queue, won't it be starving the ack?=20 > The replaced ack was much ahead in the queue than the ack we replaced = at the tail right? No, if you are doing this on enqueue, then you are comparing the new ack = with an ack immediately preceding it in the same queue, which will also = be at the tail. And if you are doing it on dequeue then both packets = were enqueued some time ago, and both are already due for delivery very = soon. In general, the second packet is delivered sooner, in place of the first = one that was removed. This means it reduces feedback latency to the = (forward path) sender. - Jonathan Morton