From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x22d.google.com (mail-lf0-x22d.google.com [IPv6:2a00:1450:4010:c07::22d]) (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 ABF773B2C4 for ; Sat, 11 Jun 2016 12:41:28 -0400 (EDT) Received: by mail-lf0-x22d.google.com with SMTP id j7so38704361lfg.1 for ; Sat, 11 Jun 2016 09:41:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=LQvdfXyfcc7Sj+T8Xl+bLltdcy3iEE9N7e4kzoBx+FY=; b=uLlxw4hpA5FkirO/FiTThcO3ATZvxBpfPGIvJYJ/jYGO9Smar1/JucVXvvkRtaG346 GUSqiR2cs+lmzFk5TMcL26x+svSyJhQ5+LLEpDJsaVUqIzbejl5LIfqNHwXrxPi7Vo1M 4jhLvmwwvfYU3V2YE3mXlIc3EhKRUFRTYLidakkwj/Cp9WvrvblyK9Vp89bd4RrDCMhv saxEqJSiN2vatz/dMoIkRYWHQtA6hMGE8oiBV8CL7zWpdcvak8TGhFUwXWtHppc40koh F0wqRO8FPMLCCaS9O59yo7RDmerHUDuvV4vneuoPSzgub0x9sXcNyc8lsIhNQVQh5o65 8Nvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=LQvdfXyfcc7Sj+T8Xl+bLltdcy3iEE9N7e4kzoBx+FY=; b=i1Lph2OldfHpAuKfIpSw7xRk6csuCujgJ2amJnZZAVY2iVOxNsU1iJVGLUoYz++M5M ARjRDqVH4BMHg9BVb5tKNVTCxisISek0a0R3VwnmFvDjRbpQ10EqsGJRtAcURrYjI38R SehE+8s+Jk88cenUkm/Cki+uotd78Jya0wwPSgK/LO6cAdgAGKdVk3AQac9DzI1HSdSG sbszGTMWjuRxQ95MrZvGFd+KWK5aCImwSWsq/WSwnnnRlRYI8Ic6Pags2OFmxgVurOEo qSr831CrKTNhDL5Gls4Ol/m+SHEBF4gn2MwuVzTRm7F+DTRuS6xSd7rGXC8nwBq7li69 ylZA== X-Gm-Message-State: ALyK8tKsKvKc1TGmhg4ZKHmxeamh4eLehuwRq6hGzVYCBcH9WIB+N45FpgO8pgLoX7DLFQ== X-Received: by 10.25.32.85 with SMTP id g82mr2322094lfg.184.1465663287282; Sat, 11 Jun 2016 09:41:27 -0700 (PDT) Received: from bass.home.chromatix.fi (87-93-1-125.bb.dnainternet.fi. [87.93.1.125]) by smtp.gmail.com with ESMTPSA id t10sm1340046lfd.18.2016.06.11.09.41.26 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 11 Jun 2016 09:41:26 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Jonathan Morton In-Reply-To: <575BD5D0.4060702@darbyshire-bryant.me.uk> Date: Sat, 11 Jun 2016 19:41:23 +0300 Cc: cake@lists.bufferbloat.net, Eric Dumazet Content-Transfer-Encoding: quoted-printable Message-Id: <98AFD8C3-2343-4B8B-BFB0-6F877161A039@gmail.com> References: <5756ADEC.9070305@darbyshire-bryant.me.uk> <8EE35B4F-5C28-41C7-8795-93A6F606B3A8@gmail.com> <5756E2CA.2020700@darbyshire-bryant.me.uk> <575BD5D0.4060702@darbyshire-bryant.me.uk> To: Kevin Darbyshire-Bryant X-Mailer: Apple Mail (2.3124) Subject: Re: [Cake] Possible BUG - parent backlog incorrectly updated in case of NET_XMIT_CN 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, 11 Jun 2016 16:41:28 -0000 > On 11 Jun, 2016, at 12:11, Kevin Darbyshire-Bryant = wrote: >=20 > And now there's a version 2 of Eric's fix: = http://marc.info/?l=3Dlinux-netdev&m=3D146507012302643&w=3D2 >=20 > Does this change apply to cake? I suppose this answers the question of which packet=E2=80=99s size = should be used in the correction factor. Of course, by this time in the = enqueue process, the original packet length has been replaced by the = overhead-corrected one in Cake, though I can save a copy for this = purpose. And there=E2=80=99s also the problem that we might not need to drop = packets as large as the incoming packet in order to fit the latter into = the queue - so this corrected correction may be *negative* (the queue is = longer than before) - but qdisc_tree_reduce_backlog() only takes an = unsigned parameter here. IMHO the NET_XMIT_CN semantics are broken. It might be better to drop = support for it, since it should rarely be triggered. - Jonathan Morton