From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x22c.google.com (mail-lf0-x22c.google.com [IPv6:2a00:1450:4010:c07::22c]) (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 EFADD3B25D; Sun, 1 May 2016 14:20:17 -0400 (EDT) Received: by mail-lf0-x22c.google.com with SMTP id j8so35554011lfd.2; Sun, 01 May 2016 11:20:17 -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=IouuOl2GvQTUbdBt+5pHjxTjvP0m8IrZprJEx3uIWA4=; b=bVSmKg4xnr5efnDSKPnx2KCO9wthfHx4Uf+v1rdjuJETyg+tict88fnLmn2KRVkPmu 6tykG0jF5i+uqtC2HGr+hlwBeBP2Yn6BJRjnxXRelw3DQpmykRG7DWHCC7F2TiA7XMK5 uhupxJgdOPIKjwR2oGC4JfMGZWzvmdCDiQD2pZ5bQgi4MUcLYkfQnHjfubswUmMe+IlG e/52kNQDwF7GjENtsLKEqu987orylxQmbvEsK1CZTbxHx0G0CDiH+iGLxxUKbxwvuwnJ onWdRupzp5GJDuDhih1WYZw8Yp5arwG5kB2nwdtISE9umfyMFlaWm4U65BlVksJhEwAe tzvw== 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=IouuOl2GvQTUbdBt+5pHjxTjvP0m8IrZprJEx3uIWA4=; b=FAcNJmgjgaAcG45y+nahJYkl+DvIHu5R5eCHiRfn8oi867R8Vth6/cXybRfko/lfuW DHFEHE9JwRrGfCh0ARiLkaQNMiyiAHv+bKR8eoKx4CfoNZdoJ9CtCM3JwVPnyRI4xVU/ SO9awLvYrmdTsIP4f8M+/8vD7khnlcOHzrhKpo8s/Yu8+eW7Cl5On/Vo+vE9xfAHgmw9 pUULJidI7qltSei/DYe96MLEHdqsDDmgrd5W1fKAdqCmQ6vfqJgIwCVVyr9nvKXD+/bZ /l3id0Vfj3IsRh2wxTirSwBqMuAsO+zJu17rHrL85W8VbNeTQ6zr633mMpTbxjsXpNtl sDkQ== X-Gm-Message-State: AOPr4FVEalRsp43KIR0FeFGIzlcxOFdH4Oa50VNDOEHykm6qJTN+y1DRynTe1CepeqBbqQ== X-Received: by 10.112.133.1 with SMTP id oy1mr4240306lbb.79.1462126816704; Sun, 01 May 2016 11:20:16 -0700 (PDT) Received: from bass.home.chromatix.fi (37-33-67-252.bb.dnainternet.fi. [37.33.67.252]) by smtp.gmail.com with ESMTPSA id jw6sm3691318lbc.13.2016.05.01.11.20.15 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 01 May 2016 11:20:16 -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: <1462125592.5535.194.camel@edumazet-glaptop3.roam.corp.google.com> Date: Sun, 1 May 2016 21:20:10 +0300 Cc: Dave Taht , make-wifi-fast@lists.bufferbloat.net, "codel@lists.bufferbloat.net" , ath10k Content-Transfer-Encoding: quoted-printable Message-Id: <865DA393-262D-40B6-A9D3-1B978CD5F6C6@gmail.com> References: <1462125592.5535.194.camel@edumazet-glaptop3.roam.corp.google.com> To: Eric Dumazet X-Mailer: Apple Mail (2.3124) Subject: Re: [Make-wifi-fast] [Codel] fq_codel_drop vs a udp flood 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, 01 May 2016 18:20:18 -0000 > On 1 May, 2016, at 20:59, Eric Dumazet wrote: >=20 > fq_codel_drop() could drop _all_ packets of the fat flow, instead of a > single one. Unfortunately, that could have bad consequences if the =E2=80=9Cfat = flow=E2=80=9D happens to be a TCP in slow-start on a long-RTT path. = Such a flow is responsive, but on an order-magnitude longer timescale = than may have been configured as optimum. The real problem is that fq_codel_drop() performs the same (excessive) = amount of work to cope with a single unresponsive flow as it would for a = true DDoS. Optimising the search function is sufficient. - Jonathan Morton