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[83.150.84.172]) by mx.google.com with ESMTPSA id e44sm5905824eeh.11.2013.06.17.20.40.55 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 17 Jun 2013 20:40:55 -0700 (PDT) Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset=us-ascii From: Jonathan Morton In-Reply-To: Date: Tue, 18 Jun 2013 06:40:54 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: <5FBEF303-322B-490A-B420-DAC80B259384@gmail.com> References: To: Dave Taht X-Mailer: Apple Mail (2.1085) Cc: iccrg@irtf.org, tsvwg@ietf.org, bloat Subject: Re: [Bloat] some comments on draft-ietf-tsvwg-byte-pkt-congest-10.txt X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Jun 2013 03:41:00 -0000 On 17 Jun, 2013, at 10:40 pm, Dave Taht wrote: > if we can agree that AQM =3D Active queue *length* management and > can come up with a name for FQ+AQM hybrids that works for people (SQM > - smart queue management?) so we know what we're talking about when > talking about things SQ =3D Smart Queueing sounds good to me, for AQM+FQ together. It should = probably also be taken to include any third or future category of = techniques that is found to work well in concert, as well. For the fourth (original) corner of the graph, PQ could mean Passive = Queueing, meaning neither AQM nor FQ - this would have to refer to = ordinary priority queues and packet aggregation as well as a dumb FIFO. = That means we need a robust definition of FQ. So AQM means any technique which seeks to maintain the average length of = the queue below the maximum, by proactively dropping or ECN-marking = packets. And FQ means any technique which uses a separate queue for each flow, or = stochastically approaches that ideal. Broadly classifying packets into = a small number of categories (as has been done since the TOS days) is = not sufficient to be FQ. An example of a third technique would be such broad packet = classification, which allocates a separate AQM+FQ combination for each = category and dequeues them according to a priority algorithm. We've = discussed such things quite recently; the main problem seems to be = identifying traffic reliably without application-level cooperation, = which is a perennial problem. > Anybody got a 68020 or slower to play with? I have a Mac IIcx (16MHz 68030+FPU) with an Ethernet card - an '030 is = pretty close to an '020 in performance per clock, if the '020 isn't = using an MMU. It has enough RAM to run Linux effectively. It doesn't = have DMA, though - a common limitation on single-user machines of the = time - which is a severe limit on throughput. Also, it probably needs = some major surgery due to age-related component degradation = (capacitors), since it currently won't power up. Ironically, I ran into = that problem just after fitting the new RAM, though it had been showing = signs of it beforehand. The next closest thing I've got is a 25MHz 486 (an IBM PS/1 in which I = swapped the original i486SX for a DX) with two Ethernet cards (one is = the well-regarded 3c509B) and an analogue modem fitted; a leftover from = my university days a decade ago. I know that it can route T1 level = speeds despite not having full-duplex Ethernet or PCI. I'd need to set = up Linux afresh on it, of course, but then I could insert it in place of = my usual firewall machine for testing. That is, of course, if it hasn't = succumbed to the same class of fault as the IIcx. The next candidate I have after that is an Acorn RiscPC, but I think a = 30MHz ARM CPU is sufficiently faster than a 68020 - *any* 68020 - to = dilute the point. Also, I don't have an Ethernet card for it, and even = if I did, it also lacks DMA hardware AFAIK. However, you could = downclock the Raspberry Pi's CPU quite a lot (edit config.txt in /boot) = if you want to explore this space - as long as the GPU and RAM clocks = remain above some threshold, everything should work. A quick look = reveals definite reports of a 50MHz CPU clock working. If you really want an '020 or '030 with DMA, the best candidates would = probably be an Amiga, a NeXT Cube or an early Sun workstation. The = latter have probably survived relatively well, and were quite likely = used for at least a few of the early performance studies that people now = habitually rely on. - Jonathan Morton