From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) (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 B3E0D3CB3D for ; Thu, 12 Dec 2019 23:42:17 -0500 (EST) Received: by mail-io1-xd2a.google.com with SMTP id b10so1035612iof.11 for ; Thu, 12 Dec 2019 20:42:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=QthJDPFS7nC/yW0U0bf8QlKUYmsIKhyJY5u98hEJawE=; b=H0QFgUExbKoezQOgWpIhAlmuOqeakyKGbYvy4ZrJ2gkih+zO1HShIaX9hTtS71m13N dJHwQR7lmjEaYwQRSbSonOeCyWI3voVQjG7O4Iw3XWm9WAWXkkyIYu5M0R7c2kT4z268 OtgzsLaBb/YwxJq0KYPIuq3wXHxvIHn7mAJlSHyatjvjDRX7xTC2ksat+g5mwK62fnRO EpjKPCYKkZIqVq7y1ZoMuSH3yZKeyPs3uAbTywiCucg12Ntxq6qaUhszvdVU+NkkyU1q MQT7Z6I+jyebIJCIu0aBJN+hfAXFH+RTyGXduNAdLiwveJL1diAFORpkIY5sDIgJNaZQ 8AAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=QthJDPFS7nC/yW0U0bf8QlKUYmsIKhyJY5u98hEJawE=; b=VBsvEminWRTIeQSdybEq/9DSL7bAYAXEjo+auZKJjVKgJIzs9HXgdfLt+ZUUSkCwem fq7PvMtzs9rsJioeDzpT8ifR4bEPfWLivD0NDQsy6T4/zTVcORKVuN18UQb3kLVKwdiQ ZHUruTygwit8Y92oSO4T1t//jaA/ViLofkr4L2UWZcmaefI8DMBzx4QRsSduwCY15qYA WHQ/vwQQCLraidVl+KmVJVaLrhFmY7xpqtiH605BG+nlji4D2CyXblg9DThc2LOuTAb/ +3wUzLBtHASgA/BpJMBoyU4oZ+hUQkXZQf2NsQvUKPinRz8azttrrxBnVmAnhZiSDczG yeLA== X-Gm-Message-State: APjAAAUu7foCDSJ2Q/l/h09Nr7GPzExwqLcOQC+bu97Lp0u83FqQoIQF je58VnRLKfMcOGswqYbWZ4R2FzyGPoD2PzjYLuE= X-Google-Smtp-Source: APXvYqzkCBPiplJckv2NvxY8N2or3/hpIB4LnKp13BL3tLkcHJukuTXjaf6kspE/nJV6QdTjfUgCLbAr9kpXuUAC3Ic= X-Received: by 2002:a02:6515:: with SMTP id u21mr10699337jab.82.1576212137023; Thu, 12 Dec 2019 20:42:17 -0800 (PST) MIME-Version: 1.0 References: <14cedbb9300f887fecc399ebcdb70c153955f876.camel@sipsolutions.net> <99748db5-7898-534b-d407-ed819f07f939@gmail.com> <22B5F072-630A-44BE-A0E5-BF814A6CB9B0@superduper.net> <34a05f62-8dd0-9ea0-2192-1da5bfe6d843@gmail.com> In-Reply-To: <34a05f62-8dd0-9ea0-2192-1da5bfe6d843@gmail.com> From: Dave Taht Date: Thu, 12 Dec 2019 20:42:04 -0800 Message-ID: To: Eric Dumazet Cc: Simon Barber , Make-Wifi-fast , Johannes Berg , linux-wireless , Neal Cardwell , Netdev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 04:42:17 -0000 On Thu, Dec 12, 2019 at 5:46 PM Eric Dumazet wrote= : > > > > On 12/12/19 4:59 PM, Simon Barber wrote: > > I=E2=80=99m currently adding ACK thinning to Linux=E2=80=99s 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. Packets accumulate in the wifi device and driver, if that's the bottleneck. > > 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. I generally have more hope for open source attempts at this than other means. And there isn't much left in TCP that will change in the future; it is an ossified protocol. 802.11n, at least, has a problem fitting many packets into an aggregate. Sending less packets is a win in multiple ways: A) Improves bi-directional throughput B) Reduces the size of the receivers txop (and retries) - the client is also often running at a lower rate than the ap. C) Delivers the most current ack, sooner When further transiting an aqm that uses random numbers, it hits the right packet sooner, also. I welcome experimentation in this area. --=20 Make Music, Not War Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729