From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x22e.google.com (mail-qt0-x22e.google.com [IPv6:2607:f8b0:400d:c0d::22e]) (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 3D7633B25E for ; Sat, 17 Sep 2016 14:53:12 -0400 (EDT) Received: by mail-qt0-x22e.google.com with SMTP id 11so56669512qtc.0 for ; Sat, 17 Sep 2016 11:53:12 -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=gx8Qqb4pb5+QgGRxu6UAutWKw4StVk4sczmkxDdaWDk=; b=wZH6Ts4W0RMTkgAEKXI6A5FVqU+rnJD0TKcmq7z0us+/qkFeKdSyqQjcrnWz4QWDbH igOUKc+1Su1XU8DxK7xNvvKFntWxHigyCfKH0t6Iu5WfSBvMTU9ltjg2Y4INFKTSQ5w0 B7gE2f3r11FCayx0rI+fOyBatngBpcBLpIOdtaFYWZDMGcXb3QD/Vai34WJKOWoplMpn 6LxxtjhroUKZJlXK/GyoLBZ5oQQmwgWHuNShivauQ0JWsqxTbXbCoYOvW9+vZX1fUYp5 Ald9Iy0EdN/s6qoa3+QmJ0dZdBs36rpBZL4uIcERlb9iIJWg1ER3MTaUhuv/+Mpyj7C7 HQ0w== 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=gx8Qqb4pb5+QgGRxu6UAutWKw4StVk4sczmkxDdaWDk=; b=jkRTCxAtvaqrnKSOTNq3wWEH044JxDqbPlknP1mlRk05Ui1yTDGIYeYtdUZuYhrU3e 8badntP/+pMCzj7OjDJamZbixi3pNDYFuY26ehP+ivzEuafv4M8ibgP3ilK7KOBjUdEo 72bvXyWRbAJWWRADKwRjWxz5LmMPy+Asc0/y2f8jkU7/9zSQmCF13dYl9xhTJ5QSiB2K Dox+cWvU+hg5IVxCcjztmPzD7xloJYNbAk7SKPbcp2IbXWggQfrg6fk3QB7dtWAcSNN1 DhAPJrERANIAf57tR8Z7m9gxnwE6JuHxnsgBkUXO2WOZyktnhzRbJsRyZ/rkijRCKpVw U1nQ== X-Gm-Message-State: AE9vXwPccrDTZweF0Tx+0PB7vYn1xHx2Zf8lv0k1e82C8YlPbO3uJkSWu0xwkAUy3n+vfbTB5yW3aOurR5prcw== X-Received: by 10.200.45.113 with SMTP id o46mr19259381qta.93.1474138391795; Sat, 17 Sep 2016 11:53:11 -0700 (PDT) MIME-Version: 1.0 Received: by 10.12.137.214 with HTTP; Sat, 17 Sep 2016 11:53:11 -0700 (PDT) In-Reply-To: References: From: Dave Taht Date: Sat, 17 Sep 2016 11:53:11 -0700 Message-ID: To: Maciej Soltysiak Cc: "cerowrt-devel@lists.bufferbloat.net" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Cerowrt-devel] BBR congestion control algorithm for TCP in net-next X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 17 Sep 2016 18:53:12 -0000 BBR is pretty awesome, and it's one of the reasons why I stopped sweating inbound rate limiting + fq_codel as much as I used to. I have a blog entry pending on this but wasn't expecting the code to be released before the paper was... and all I had to go on til yesterday was Nowlan's dissertation: http://blog.cerowrt.org/papers/bbr_thesis.pdf which seemed closer to good than anything I'd read before, but still wrong in a few respects, which has taken a few years to sort out. I think reading the upcoming acm queue paper is going to be fun! I think they have identified the right variables to probe - RTT and bandwidth, in sequence - for modern congestion control to work much better. Still BBR makes a few assumptions that do not hold (or so I think) - with wifi in the control loop, and it needs wider testing in more circumstances than just google facing out - like on itty bitty nas's and media servers - and especially seeing what happens when it interacts with fq_codel and cake would be good to see. I've watched youtube be *excellent* for 2 years now, and only had the faintest hints as to why. It was quite amusing that the original patchset didn't compile on 32 bit platforms. And make no mistake - it still makes plenty of sense to apply fq_codel-like algorithms to routers, and the stuff we just did to wifi for fq_codel and airtime fairness. Had I thought BBR solved everything I'd have quit years ago. On Sat, Sep 17, 2016 at 11:34 AM, Maciej Soltysiak w= rote: > Hi, > > Just saw this: https://patchwork.ozlabs.org/patch/671069/ > > Interested to see how BBR would play out with things like fq_codel or cak= e. > > "loss-based congestion control is unfortunately out-dated in today's > networks. On > today's Internet, loss-based congestion control causes the infamous > bufferbloat problem" > > So, instead of waiting for packet loss they probe and measure, e.g. when > doing slow start (here called STARTUP) they don't speed up until packet > loss, but slow down before reaching estimated bandwidth level. > > Cake and fq_codel work on all packets and aim to signal packet loss early= to > network stacks by dropping; BBR works on TCP and aims to prevent packet > loss. > > > Best regards, > Maciej > > > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel > --=20 Dave T=C3=A4ht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org