From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id BB32521F3DA for ; Sun, 1 Nov 2015 01:47:00 -0800 (PST) Received: from hms-beagle.home.lan ([217.237.68.126]) by mail.gmx.com (mrgmx003) with ESMTPSA (Nemesis) id 0Lhwt0-1aFFcb0j46-00n8qB; Sun, 01 Nov 2015 10:46:55 +0100 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) From: Sebastian Moeller In-Reply-To: Date: Sun, 1 Nov 2015 10:47:24 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <7F32378C-878D-437C-B56C-F8E5B0D99895@gmx.de> References: <563517E5.4050202@darbyshire-bryant.me.uk> To: =?windows-1252?Q?Dave_T=E4ht?= X-Mailer: Apple Mail (2.1878.6) X-Provags-ID: V03:K0:/laDoH1TLmOHTBvdtTw8YNomh6RwxlcAME5QfXjZ8U+QczI0Wpc wX3Dw4o58UV34qBbqFW5nOnTiGFNknKiAvaZzIQTO8y9FMz1jwMgy9BD55xgo88MI4Jm0AS rGcFTTElGBkxoVNT0v1CG3dmYcyBfSDW3quiCfyBtu7Z6UYUqv7A8NgjunyPwIqTpPTFP0m QtXnFgY7hFOeavuZohAcA== X-UI-Out-Filterresults: notjunk:1;V01:K0:LcAuGm17+E0=:RtoYyE9DcO4NVHDmePhe/X EHlYIL0OciZYwx78hnG7+vpo/Hr1ygGYDYHs0vaRZZAaDdZ0Z51u96Rj6b4KB/oEoCkiwd8fe /B7fYP73uPZq2bq6A5e3c29ngUcBTLXA4kC3l021r0PCrV8wIYDDF6AwhJcsKDQtVFl9EzgyZ MQVCRL4UtLjWJPHpwBBopPxbzwObXiqybUWeoT8GfzTgRSz2SO1IYsQpLsP+cseLNc0FQ9jWN pc/RJ8i3gv2BXVAv9BDCbQ7EtrrVKTqMcO8PxAU6Pkt80oqA2L93u+tCjXWj6JnhtIQHd2iCt LE0uCVCyLb+z6wkNEQslHTh1XidKyrk1lNOGUmIMXhLZ5YvhKrPdOQPkUHlv/qwgAaTz37wk/ uoCHUxEyFRpwhvDF8KLkHtdkooGC8+Kb0aUPXm2YYUnfGYbYTbn1lBy5ejd5NjQC7kcnNORU6 ILwaiwD0Tn1zWceFm4uUDrP5DvXF1cE6tERk80XOjxRNuLHYYOWYmXqjTUT0t++hfwjRAyzyS BFo2pVmdSAKKa8Y45aNWpnLEfal/eUM8D7EeZryLBdSU1tSV/3DEEGVTbvFpBe+h/dkCZcYDO 9jeiN10sEX7MjyMBr2plOG4kq1jWmavVIh0hLIIeJ5hRtbHPm6snbNhhyx8/MsHWksAD7/Ekl M3d7BO3REzvjrGCntEq7lO7Xqw9H2z77ATKq6zJDjMxeK4vbD/KIuU9oqBixFk0DaWeGV2aDJ sLTZMUH8u0oKF9eZoe2W7QNn4/O2xdOQM3jalNcq98+szC47zTLHOYkUfWCpdRIRZWO4sJ4SH VY6zPnH Cc: cake@lists.bufferbloat.net Subject: Re: [Cake] Stranger target behaviour X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Nov 2015 09:47:24 -0000 Hi there, On Oct 31, 2015, at 21:29 , Dave Taht wrote: > The second one is from the interval >> 4, which equates to 6.2ms. I > note I picked that because some early data (2012) we had showed that > target slightly greater than cable media acquision (6ms) time was a > slight win, and it did not hurt to use a number more evenly divisible > in binary than the arbitrary 5%. Well, but should it not be 6.2ms even if no rtt is explicitly = requested? Currently cake has a lot of corer-cases that are not too well = documented either. >=20 > Also there was somewhere else in the original code where I'd stopped > using the target variable entirely and just used the shifted interval, > but given low rates where we have to account for the MTU, that > approach does not work. (otherwise anytime I can replace a memory > access with a mere shift, I'd do it) Why? We could take the initial target, calculate the adjusted = target, multiply that by 16 to get the adjusted interval/rtt; at that = point target =3D interval >> 4 is true again ;) >=20 > As for the first 5ms sample below, I am really behind on keeping up > with the code. After next weekend I would hope to have time, but I do > hope someone can step through all the permutations upon which init and > change can be called to nail it. I believe while we are at it we should reconsider the BUG_ONs; I = believe it is going to be a hard sell for the kernel community to hose a = whole system because a qdisc was a bit unhappy ;) I also want to repeat = my conviction that the buffer limit needs to be exposed to the user and = actually honored as a hard limit. I believe cake is aimed at non-expert = users and having rtt and bandwidth settings have un-obviuos side effects = on the worst case memory consumption does not seem suitable for = non-experts... >=20 > Somewhere on these threads someone suggested moving the target > calculation into userspace, which does not work well, IMHO, when cake > is the default qdisc, I believe before that happens cake will need to acquire = pfifo_fast priority bands as default ;); regarding the default qdisc = issue, I hess the challenge is that nothing passes anything into = sch_cake if it is the default, then obviously it should default to rtt = 100ms target 6.2ms=85 So I should include cake as default qdisc in the = cursory testing I do. > and we somehow get a means to actually get the > actual line rate. But we are far away from that, no? Best Regards Sebastian > Dave T=E4ht > I just invested five years of my life to making wifi better. And, > now... the FCC wants to make my work, illegal for people to install. > https://www.gofundme.com/savewifi >=20 >=20 > On Sat, Oct 31, 2015 at 3:35 PM, Kevin Darbyshire-Bryant > wrote: >> Playing with latest JM authed commits on sch-cake & tc-adv. Look at = the >> target values: >>=20 >> root@Router:~# tc -s qdisc change dev ifb4eth0 root cake internet >> root@Router:~# tc -s qdisc show dev ifb4eth0 >> qdisc cake 8008: root refcnt 2 bandwidth 39300Kbit diffserv4 flows = rtt >> 100.0ms noatm overhead 12 >> Sent 285837 bytes 1240 pkt (dropped 0, overlimits 144 requeues 0) >> backlog 0b 0p requeues 0 >> capacity estimate: 10511Kbit >> Tin 0 Tin 1 Tin 2 Tin 3 >> thresh 39300Kbit 36843Kbit 29475Kbit 9825Kbit >> target 5.0ms 5.0ms 5.0ms 5.0ms >> interval 100.0ms 100.0ms 100.0ms 100.0ms >> Pk-delay 0us 22us 0us 0us >> Av-delay 0us 6us 0us 0us >> Sp-delay 0us 2us 0us 0us >> pkts 0 1240 0 0 >> bytes 0 285837 0 0 >> way-inds 0 0 0 0 >> way-miss 0 125 0 0 >> way-cols 0 0 0 0 >> drops 0 0 0 0 >> marks 0 0 0 0 >> Sp-flows 0 0 0 0 >> Bk-flows 0 2 0 0 >> last-len 0 82 0 0 >> max-len 0 1514 0 0 >>=20 >> root@Router:~# tc -s qdisc change dev ifb4eth0 root cake rtt 100ms >> root@Router:~# tc -s qdisc show dev ifb4eth0 >> qdisc cake 8008: root refcnt 2 bandwidth 39300Kbit diffserv4 flows = rtt >> 100.0ms noatm overhead 12 >> Sent 757689 bytes 2374 pkt (dropped 0, overlimits 464 requeues 0) >> backlog 0b 0p requeues 0 >> capacity estimate: 5964Kbit >> Tin 0 Tin 1 Tin 2 Tin 3 >> thresh 39300Kbit 36843Kbit 29475Kbit 9825Kbit >> target 6.2ms 6.2ms 6.2ms 6.2ms >> interval 100.0ms 100.0ms 100.0ms 100.0ms >> Pk-delay 0us 286us 0us 0us >> Av-delay 0us 70us 0us 0us >> Sp-delay 0us 2us 0us 0us >> pkts 0 2374 0 0 >> bytes 0 757689 0 0 >> way-inds 0 0 0 0 >> way-miss 0 157 0 0 >> way-cols 0 0 0 0 >> drops 0 0 0 0 >> marks 0 0 0 0 >> Sp-flows 0 0 0 0 >> Bk-flows 0 2 0 0 >> last-len 0 82 0 0 >> max-len 0 1514 0 0 >>=20 >> Colour me confused :-) >>=20 >> Kevin >>=20 >>=20 >> _______________________________________________ >> Cake mailing list >> Cake@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/cake >>=20 > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake