From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) (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 9097F3CB3D for ; Thu, 12 Dec 2019 20:46:58 -0500 (EST) Received: by mail-pg1-x536.google.com with SMTP id s64so690389pgb.9 for ; Thu, 12 Dec 2019 17:46:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=DQN+c/XoQHFCxSakIJRYUeZx27nMrip4+1yJpWHdOaU=; b=eiOUp9daulK1XiDWuJczbXZ91xl5eAYXTVgIDlIyHXD3ph+vj2XY25A9md64czwV5A Bpund4OeiqP8MfMBrPTHKcGWfduxfCzUAS/oZZnoEHYdCID4uuvGVBWicDYmT5CBZS3o HCemndy7tV/uErRxeGC2Jjxah+qzX0v02rhssWsd4szHdBEaQttBrknRum+Roi43iFMA mObyfolVtIiY7A5faifRIhViFDB5o8qJ0v3dDTYog1JsGz3bhN+KDJ/hwduwoNgppUOv PO1wEM4ZoAKd3IhpwneynsiTrFZ6FlyyOZxGY+3lqN7fdJ2ksT5gupdY+k4Ro2heDtS/ 4UMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=DQN+c/XoQHFCxSakIJRYUeZx27nMrip4+1yJpWHdOaU=; b=ahXFZdobm8vSqvkBqj1h/Hak9loBvyyjiPSphsIql+xXOgsp3zButvolRnj/a/ylkY 2FrkwdlnR/ArH75qsvRSsUY0VcTjns2ih9fo18hnq7F18BWYNTxOyQydRfSeEWWD6+7D acKHCwhSiB0LB2BnSm5EqSeXqtUf2ihcL98u5lQORtrpD82QRnMtPIIjvM+arq3X68nT 6miVzPnDqXPf0aXbUlPZRILUM0hVG4h1o61F2UKEPhwhsc0sSqyroEqbIQyf6T/SwWmK zJVRREYEqls0oIL9A9A97HMcl1rNXvn3/wduoTFFRmcHuf/4OkxqGd5vv7t1ctjO1Yzb /d0g== X-Gm-Message-State: APjAAAUgCeClzMV4nB4GZBjpgoowX5m9nIxkCJC9p8DKbBG7youRsL2C GfkmHSSbakmTdHZPu4T2GKU= X-Google-Smtp-Source: APXvYqxFZPh4/9ddIRpKT1XLG5JlQjBS84W0h/mzO8dD9Xl++O9QBZnfTuw55gnq4SN5IK8VHMF8Tg== X-Received: by 2002:a65:488f:: with SMTP id n15mr14683013pgs.61.1576201617698; Thu, 12 Dec 2019 17:46:57 -0800 (PST) Received: from [192.168.86.235] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id e27sm8910691pfj.129.2019.12.12.17.46.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Dec 2019 17:46:56 -0800 (PST) To: Simon Barber , Dave Taht Cc: Make-Wifi-fast , Johannes Berg , linux-wireless , Neal Cardwell , Netdev References: <14cedbb9300f887fecc399ebcdb70c153955f876.camel@sipsolutions.net> <99748db5-7898-534b-d407-ed819f07f939@gmail.com> <22B5F072-630A-44BE-A0E5-BF814A6CB9B0@superduper.net> From: Eric Dumazet Message-ID: <34a05f62-8dd0-9ea0-2192-1da5bfe6d843@gmail.com> Date: Thu, 12 Dec 2019 17:46:55 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <22B5F072-630A-44BE-A0E5-BF814A6CB9B0@superduper.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [Make-wifi-fast] debugging TCP stalls on high-speed wifi 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: Fri, 13 Dec 2019 01:46:58 -0000 On 12/12/19 4:59 PM, Simon Barber wrote: > I’m currently adding ACK thinning to Linux’s GRO code. Quite a simple addition given the way that code works. > > Simon > > Please don't. 1) It will not help since many NIC do not use GRO. 2) This does not help if you receive one ACK per NIC interrupt, which is quite common. 3) This breaks GRO transparency. 4) TCP can implement this in a more effective/controlled way, since the peer know a lot more flow characteristics. Middle-box should not try to make TCP better, they usually break things.