From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-x243.google.com (mail-qk0-x243.google.com [IPv6:2607:f8b0:400d:c09::243]) (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 2D2593B25E for ; Thu, 27 Oct 2016 13:59:27 -0400 (EDT) Received: by mail-qk0-x243.google.com with SMTP id x11so3044746qka.0 for ; Thu, 27 Oct 2016 10:59:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Bwr/h/o0Ey8K+4pCu/Wu89qIfHWBsPACQ0R5IYTLrI0=; b=n6/clP69Yyx2m3Faf/Sh8nJyWxNH/4riJ0xJQDcV1LeocnvDd4yg/H7BjUaum+CHd5 r5sH7lALMcHL3kr+bcQDB3qET9mLk8qaat8fqOVTHy8aTBqQUI5KSpIOYPB4AQwviqIK 0y3Mn8frXXaLqj7pDd8NMuSfB+LINqvnxmxEaSFnWvLlA0g7FsLn8j7vCGUNaUTmpNaN F3GVrFaHzKK1mSblX0BB0jNCfbz83LpWblnbA/xIWUFMLgJiVn4FCZIj4Dd8wRIB8fdr LZCeaH5ggdOTgv4MYm0mGLLksLj+iSdrp+BEH4hWd8gDWIjhpjXRpJyl8qZrtR/L+1up fiRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Bwr/h/o0Ey8K+4pCu/Wu89qIfHWBsPACQ0R5IYTLrI0=; b=NMi6YwsK45VYpjSk5RkqHLQRlhIraOklDsWsU1O3I0kt3o333aguZXX2+mIh9Hdksu HmwF888tsqJIAIsuuotOfM9dANXJ6pizf0bFQNyOIAXOj3FQ5QN7CZNgrw+M6vQP20oC 9lnZlBOFcLHBUay8v9gYydLwmFO23ZkzfoOm1hnKKhzGQpELsUtKQMQynNs223T7orHs +kEzeUVha8nvfqc1TbihRJNvU0tQX2f2Pw8A4tGk0l3fI4lhcBOsjcU2LlfXQA//ZHTv 2lUm4Bzdy14OJ88vH81GRR3revip6VJ0G0wpjrunaJqnz2teNKe55g7cENWnNDdJ82qL rlFA== X-Gm-Message-State: ABUngvdAE1zHjl6PbGOpr2EeBzamqLfdzW/3dPOGGWiEjcLJjMaPwGIAuODOMuFkZqvQWS8jGRF2Mx3yFZ0iZA== X-Received: by 10.55.221.29 with SMTP id n29mr8540213qki.114.1477591166772; Thu, 27 Oct 2016 10:59:26 -0700 (PDT) MIME-Version: 1.0 Received: by 10.12.146.164 with HTTP; Thu, 27 Oct 2016 10:59:26 -0700 (PDT) In-Reply-To: <1477590728.7065.231.camel@edumazet-glaptop3.roam.corp.google.com> References: <20161021084726.GA1913@sesse.net> <20161027170447.GA28383@sesse.net> <1477590728.7065.231.camel@edumazet-glaptop3.roam.corp.google.com> From: Dave Taht Date: Thu, 27 Oct 2016 10:59:26 -0700 Message-ID: To: Eric Dumazet Cc: "Steinar H. Gunderson" , bloat Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] "BBR" TCP patches submitted to linux kernel X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Oct 2016 17:59:27 -0000 On Thu, Oct 27, 2016 at 10:52 AM, Eric Dumazet wro= te: > On Thu, 2016-10-27 at 10:33 -0700, Dave Taht wrote: > >> At the moment my biggest beef with BBR is that it ignores ECN entirely >> (and yet negotiates it). > > Note that switching cubic to any other CC like BBR is allowed at any > time, way after ECN was negotiated. > > So BBR can not solve the issue you mention in a reliable way. > > There must be a reason sysctl_tcp_ecn default value is 2 on linux [1], > don't you think ??? > > _You_ chose to change this sysctl, do not blame BBR for being silly ! While I chose to do so on portions of my deployment, there is the larger problem that Apple has enabled it nearly universally on iOS and OSX over the past year. > ECN was a nice attempt, but suffers from implementation bugs. Believe me, I'm not huge on it either! > > For a start, linux does not implement RFC 3540. > > If someone cares enough of ECN, then it should cook linux patches to > implement RFC 3540. Hint hint hint. > > Then you need to make sure all the nodes between your peers are not > messing with ECN. > > BBR simply works, because it is a sender side thing. > You do not have to fix everything in the Internet. > > [1] > Documentation/networking/ip-sysctl.txt > tcp_ecn - INTEGER > Control use of Explicit Congestion Notification (ECN) by TCP. > ECN is used only when both ends of the TCP connection indicate > support for it. This feature is useful in avoiding losses due > to congestion by allowing supporting routers to signal > congestion before having to drop packets. > Possible values are: > 0 Disable ECN. Neither initiate nor accept ECN. > 1 Enable ECN when requested by incoming connections and > also request ECN on outgoing connection attempts. > 2 Enable ECN when requested by incoming connections > but do not request ECN on outgoing connections. > Default: 2 > > --=20 Dave T=C3=A4ht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org