From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-x232.google.com (mail-lb0-x232.google.com [IPv6:2a00:1450:4010:c04::232]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id B70E021F1AF; Wed, 18 Mar 2015 01:42:50 -0700 (PDT) Received: by lbbzq9 with SMTP id zq9so24514949lbb.0; Wed, 18 Mar 2015 01:42:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=bDQ3km/AXUL/8EPi2gCPmf4HhksEf0yh9DzfTdWJS9s=; b=jzOecw3YUOUv7Lnjy81UI0rd7uvcZJ5UeO5X0Pehld0fkJW035z42TlxLTpVHn4mm1 6gbL5yj8Y17PyWfZSdfeR52vX3MUpRQ7GH90XtoJ7wOshPGKIaXHL1LeN2jjAprscbo2 uVBluEvZhGYIDKnN/TO2zr+LChfzcCCJhZvA2g8GQ95gbTu02WWng9SEnKLoJRy/2jpi nemn+23kywQmBiFSQbVSbs5KnYANQ8sE5aWcGN6dMtzJdK97DkX+60TCNhiOnQgw4uWw nVCVBDX0XpBc87A2Esc2RTLpVrj8LKRr3fqE9Eo0u5o6M+zcg/N+RR7/4dpeMxVl+xCK jDjg== X-Received: by 10.152.43.229 with SMTP id z5mr56041103lal.48.1426668167913; Wed, 18 Mar 2015 01:42:47 -0700 (PDT) Received: from [192.168.43.25] (188-67-138-157.bb.dnainternet.fi. [188.67.138.157]) by mx.google.com with ESMTPSA id j7sm3248512lae.9.2015.03.18.01.42.45 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 18 Mar 2015 01:42:46 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2070.6\)) From: Jonathan Morton In-Reply-To: Date: Wed, 18 Mar 2015 10:41:41 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <8BA791D1-E86E-4411-9081-1D1DC3D3D810@gmail.com> References: <7081A75C-899A-4DB7-8D77-935A37B362D8@gmail.com> To: Sebastian Moeller X-Mailer: Apple Mail (2.2070.6) Cc: codel@lists.bufferbloat.net, cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] [Codel] The next slice of cake X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 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: Wed, 18 Mar 2015 08:43:19 -0000 > I wonder, are the low priority classes configured with a guaranteed = minimum bandwidth to avoid starvation? And will they opportunistically = grab all left over bandwidth to fill the pipe? Then speed test should = just work as long as there is no competing traffic=E2=80=A6 The problem is that, in the present version, *only* the bulk/background = class can use the full pipe. Best effort gets a large fraction as its = limit, but it=E2=80=99s not full. Existing speed tests use best-effort = traffic, and that=E2=80=99s not likely to change soon. The next version should change that. > I am probably out of my mind, but couldn't it help if cake would allow = a fixed cycle mode where it would process 50ms or so worth of packets = pass them to the interface, and then sleep until the next 50ms block = start. This should just be a fallback mode to not degrade badly under = overload=E2=80=A6 There is already such a mode to cope with limited-resolution timers and = the existing overheads. Without it, the Pentium-MMX is limited to a = rather low rate (since it then has to wait for a timer interrupt for = alternate packets). At 50Mbps+, it=E2=80=99s not too far off what it = can bridge without shaping (60Mbps+). For some reason, the little CPE = boxes still lose more performance than that to shaping. Note that due to the very nature of shaping, the link is always either = effectively idle (in which case an arriving packet is dispatched = immediately, without waiting for a timer), or overloaded (in which case = packets are delivered according to a schedule). The question is whether = the shaping rate also overloads the hardware. In any case, bursting for fifty whole milliseconds at a time would = absolutely *destroy* cake=E2=80=99s latency performance. I=E2=80=99m = not going to do that. Accommodating timer performance is the only = concession to bursting I=E2=80=99m willing to make. > I think the highest priority band should only get its bandwidth quota, = and have no silent priority demotion; but otherwise I think that idea = that classes can pick up unused bandwidth sounds sane, especially for = best effort and background. Let=E2=80=99s see how well it works this way. It should be fairly easy = to adjust this aspect of behaviour later on. - Jonathan Morton