From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x236.google.com (mail-lf0-x236.google.com [IPv6:2a00:1450:4010:c07::236]) (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 9C5F13B25D for ; Sun, 3 Jul 2016 03:50:45 -0400 (EDT) Received: by mail-lf0-x236.google.com with SMTP id h129so100464700lfh.1 for ; Sun, 03 Jul 2016 00:50:45 -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=7Nu711sP7VDEM0eE8T0Ow1o6YHAMAi8hHh45C5FlTfQ=; b=tOmixxonExxEjdLQL7AtLdTHKJD3EgORvg/5N37nO/QGH3ti2ilcXJsc9ETfWiNMFz 5IzHkls22NNvPdMuO5y38hcPlbLypuShk/nT4veS950TCsaXi44BtqpRKjcxrxqNFylz YTlBbpoq4uzp4SgwHL9H0+lnCknO/W7wrIKvIutR7za6jPLEEIq3R5l05xEbU5TWmTAv 4uOBDK1Thkfz63Q65JAtdy1Nk4TTrcIfffwwVTod2YfRiKNSGtW6woZlZbSL31BOO/c5 x9i6CPkqXiNO3DWML2l27r/cEZT7bjV3r96ZqUKh1nhxBfRDuo+dAXSLr6i0HVCHFIAS ICrg== 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=7Nu711sP7VDEM0eE8T0Ow1o6YHAMAi8hHh45C5FlTfQ=; b=MtZ+WB7VXYswt7qSI+zrJU4AL2NN5v4EvaglfeBrbcaNIGGXxCn6EZ9HlccdaYI9QE k5ndxgL5vJiLsttuiuhAaK0w2kTw/pVFxUJLb0FGm9B3TsMgvxKRcWkvvFta1sQYX4pd /GvJ6Le28SwCL+Fa98ssGzKrTtcAVU73IXudo/fAv5BPk3aavAd2FvSEz1jNPbUCBX00 6zb0h8TIeT+rJnBZiij5YRkqS5L4vaSTlG0YWKoSdk9MmTaOT+EVxwaIWFG0erVvOvcj MrKsjFayHvwEVPgmPLGlpCuSz4/1QrPD4OT33U+WFnr+kKsZ6E1xu5ErxWZB2n7f7tAd axlQ== X-Gm-Message-State: ALyK8tJ2QkPfbFVJnnoiBvPUF4JR9/L86L4WqNqbvQcGbqHhHkAmTI1Ki1/F+5175I8ngw== X-Received: by 10.25.26.194 with SMTP id a185mr1199430lfa.156.1467532244397; Sun, 03 Jul 2016 00:50:44 -0700 (PDT) Received: from bass.home.chromatix.fi (37-33-96-207.bb.dnainternet.fi. [37.33.96.207]) by smtp.gmail.com with ESMTPSA id l79sm1364335lfi.40.2016.07.03.00.50.43 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 03 Jul 2016 00:50:43 -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: Date: Sun, 3 Jul 2016 10:50:42 +0300 Cc: Luca Muscariello , "make-wifi-fast@lists.bufferbloat.net" Content-Transfer-Encoding: quoted-printable Message-Id: References: <87ziq2o07z.fsf@toke.dk> To: David Lang X-Mailer: Apple Mail (2.3124) Subject: Re: [Make-wifi-fast] On the 802.11 performance anomaly and an airtime fairness scheduler to fix it X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Jul 2016 07:50:45 -0000 > On 3 Jul, 2016, at 10:06, David Lang wrote: >=20 > do they delay the L2 Ack until the L4 ack comes back? If so, how does = that work on long-latency connections where it takes a long time for the = L4 ack to show up? I=E2=80=99m pretty sure it=E2=80=99s only meant to work when the TCP = endpoint is local to the receiving station, assuring low turnaround = latency. This is the typical case, so it=E2=80=99s a win. With that said, there=E2=80=99s no fundamental reason why the = piggybacked L4 ack need be the one corresponding to the L2 ack. It just = needs to be a small packet that won=E2=80=99t unduly extend the airtime = occupied by the ack anyway, and which won=E2=80=99t mind being lost if = the L2 ack gets squashed. A scheme allowing a certain amount of slop in = this way would accommodate remote TCP endpoints as well as local ones. - Jonathan Morton