From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x241.google.com (mail-wm0-x241.google.com [IPv6:2a00:1450:400c:c09::241]) (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 2500E3B2A3 for ; Fri, 28 Apr 2017 17:11:39 -0400 (EDT) Received: by mail-wm0-x241.google.com with SMTP id d79so13205318wmi.2 for ; Fri, 28 Apr 2017 14:11:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:reply-to :user-agent:mime-version:content-transfer-encoding; bh=WEXdrnj3gIjYsxvRPX6G5u79HEA4dRgYtekWkyzAfvU=; b=C0hh9Wu+M6Y5vtBYoN0IAQLFr67ErqaHiEC91YzX8mbFInLadV/RYaY0TFmzLvvSeF DN0w8/1kfrf4BEoWimvq3mjps3jjp/23tla03zHoKsosi/XXTR9YaIzt87Cy80uPxfT7 SgAr1UoqIvUTSgeFI7coLRFdNnM2AcxknoYr/RkkRQHnKkvMCzYEEmfQl2+/6M9v/2kT paPRZ1ILPh14FBE5QFwRTKfa5VvJ8cLQdAugE2IJeQyv0wLTLFl4kz88zPS2X+S9IFUU GD/8vJ/AnX1BURYnF+mLzr8U00eMs/TQ6EWAXoT4KU1KYc71IMkO7855CqTNfz1VwS6D 5CNQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:reply-to:user-agent:mime-version :content-transfer-encoding; bh=WEXdrnj3gIjYsxvRPX6G5u79HEA4dRgYtekWkyzAfvU=; b=gk/kakb5TpUnPLnLWmjb7/40pgBT3ZOnDJv9rbo391PkxUpZoJ1rXpzAWj06e7Qrua B3GBbSuyyt1llGkWtZqdx2ss0j9oB7QdjmxSY9KMc6OWqLIF++/nYY+DkC9W5mipUUy2 416NsgYS/vkxNAafLievx6sLLLaCmgveAopzADOpRDgHA+36T3S6zMs5IHF3AZ7aH8HK K3UD0XAKi9uDaItcav69WeR0iOGi9h5Da/HpyDmNXuQJa1/SC2KdCXY9uFvO4ZOhY2sO ZEuXlQYGmPYSQTTw8tDei23aJtzC6GchJm9RHyDOmFAcLwZN+YM9xB8h2IbqBilw9GK4 NbGA== X-Gm-Message-State: AN3rC/4QS9gqJadrc4wtAc23Llp9lKhqpIKbtyuAwow19QNbQtVLAMtv OrgEGaJk9IInDg== X-Received: by 10.28.154.85 with SMTP id c82mr109332wme.100.1493413898268; Fri, 28 Apr 2017 14:11:38 -0700 (PDT) Received: from [192.168.1.116] (cm149-53.liwest.at. [81.10.149.53]) by smtp.gmail.com with ESMTPSA id m185sm561290wma.7.2017.04.28.14.11.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Apr 2017 14:11:37 -0700 (PDT) From: xnor To: "Andy Furniss" , Cake@lists.bufferbloat.net Date: Fri, 28 Apr 2017 21:11:36 +0000 Message-Id: In-Reply-To: References: Reply-To: xnor User-Agent: eM_Client/7.0.27943.0 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Cake] cake default target is too low for bbr? X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Apr 2017 21:11:39 -0000 Hello, As I understand it, increase in RTT due to queueing of packets is the=20 main feedback mechanism for BBR. So dropping packets, which I already consider harmful, is really harmful= =20 with BBR because you're not telling the sender to slow down. Instead, with a controlled delay qdisc like cake or codel, you're=20 telling the sender to keep sending the data faster because the qdisc=20 keeps the increase in RTT minimal. To make things worse, you're throwing= =20 away perfectly good packets with no effect other than wasting bandwidth. I'm not sure how BBR handles jitter or how small of an increase in RTT=20 it detects as "congestion" but from my limited testing, I've noticed no=20 problems with steam downloads in the bulk tin with 15 ms target in cake.