From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x229.google.com (mail-qt0-x229.google.com [IPv6:2607:f8b0:400d:c0d::229]) (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 C865C3B29E for ; Tue, 18 Sep 2018 19:31:42 -0400 (EDT) Received: by mail-qt0-x229.google.com with SMTP id h4-v6so3447856qtj.7 for ; Tue, 18 Sep 2018 16:31:42 -0700 (PDT) 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=uHH3F/Zu24HeJIOgfVRhcOiisZIRoRa2D1hg1fjFa/g=; b=RWM7x+VaNXrddKNWHUDk4fhQZHtziLtn4UWUvk++RfgpHCEySei6nC3hKruUmVrCHF hvN+B4sb97k6z35LrDurVWQ0M51PFP/VqPS8IOKAxYhrAodbpXHaeZn3x4QY2fjzRonE L3OSzO2XOkUWJ46EbH4BWSoUdjzPqu1AQ0QrzpiczGtDP00zTK9fhLxTI3CYPTaQQUHF 7An4J/vUmYPeIxJ/oQ0LXYdsbBdkmTHdqkWJDg4/m/hEFsSni3TtBvaulHFD5HlTL1+m VheZ3ievYVLGgCE4fE4tpb0rkJqyMrtOFq6SpJVx676AQrhpUvseXFh97Q+UTtqkeuwc HfkQ== 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=uHH3F/Zu24HeJIOgfVRhcOiisZIRoRa2D1hg1fjFa/g=; b=K2leSPtel3n4zW5IfqHLvyNQylTZjijvPik0OcCElh7wc6tY1aA7tmhkHPTTIkMtgM Z5hmz0Z9TAfdlOICEYN/ebmCPR3zLV/jASykEp2fCWrye+8IBLqt9aNSd5gGBXmgQSEx SI3FEeYVdTt/n20jN+N5ltjXf0fPJJe5EpT8oLZKZvYZemgPuweAjDHbBeOiOQQboNQG /MvZUfMmTQHOygR1mKDQ4yikqgSuNrRiN+cuwshs/dCGmgyPYZ+mKP45ahbKA7j9KRJk a8bQA8c0MCQ5dPdMtjHto5TWaGV1o2keGFZ3wyvDiIyhryn6t1CtIq1cvDnjZ+hQNYxB ZfQA== X-Gm-Message-State: APzg51Ao1bslKt//Vztz2+54TOlON5phrF5mRSXHg2/bu4+HcQJIs3gX TDOcIJdvstOjRmrn6i8nJtN/mjmfv59/4zvfVCQ= X-Google-Smtp-Source: ANB0VdZkSnyVlAP1VVDM0Sq4lh2rNEKcFOU7NzwYbFZugZqxmgYVeegRHeU5hy5FgzZc1BRk1Xc14uB8gFSI3ySqGZE= X-Received: by 2002:a0c:9922:: with SMTP id h31-v6mr22431972qvd.206.1537313502247; Tue, 18 Sep 2018 16:31:42 -0700 (PDT) MIME-Version: 1.0 References: <87efdqcs28.wl-jch@irif.fr> In-Reply-To: <87efdqcs28.wl-jch@irif.fr> From: Dave Taht Date: Tue, 18 Sep 2018 16:31:29 -0700 Message-ID: To: Juliusz Chroboczek Cc: babel-users@lists.alioth.debian.org, Make-Wifi-fast Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] [Babel-users] reducing delays in wifi mcast queues 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: Tue, 18 Sep 2018 23:31:42 -0000 welcome back! On Tue, Sep 18, 2018 at 4:19 PM Juliusz Chroboczek wrote: > > > (I ran across this babelweb pic from my old c.h.i.p + rtod experience, > > which cracked 16sec of delay in the mcast queue: > > Bufferbloat in the driver queues? In that case yes, the driver had an infinitely long mcast queue. Once the number of routes cracked a certain point, updates across the 1mbit "bus" hit RFC970. One answer of course is to fix the driver (which I never got around to), another is to think about some sort of delay based rate control, and to ensure hello packets get out on reasonable intervals. ... Now that bufferbloat is fixed in several wifi cards (ath9k, ath10k, mt76, and soon iwl), and we don't have infinitely long queues... new problems are rearing their heads. Recently I tried to deploy a few babel 1.8.2 nodes with the latest openwrt, which I had to back out rapidly because I was dropping so many babel packets under contention. A patch to universally enable babel ecn in net.c "solves" this problem, even with no defined response, my network - particularly the congested gw in the middle - got a *ton* more reliable. But this opens whole cans of worms as to what the right approach is to respond to CE marks (mine is to treat it like a loss - or like half a loss - but to never expire the route merely because it is congested) - and doesn't solve the infinite queue problem either. Honestly I'd hoped to have unicast to deploy rather than continue to fiddle with ecn. https://www.bufferbloat.net/projects/ecn-sane/wiki/ --=20 Dave T=C3=A4ht CEO, TekLibre, LLC http://www.teklibre.com Tel: 1-669-226-2619