From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 4CDC721F151 for ; Sat, 24 Aug 2013 16:08:15 -0700 (PDT) Received: from hms-beagle-2.home.lan ([79.229.225.62]) by mail.gmx.com (mrgmx001) with ESMTPSA (Nemesis) id 0MMTEM-1V8OJu1H7m-008LLQ for ; Sun, 25 Aug 2013 01:08:12 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 6.5 \(1508\)) From: Sebastian Moeller In-Reply-To: Date: Sun, 25 Aug 2013 01:08:11 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <0CDE3FA3-FB17-47E5-AB27-2C213F716C1D@gmx.de> References: <56B261F1-2277-457C-9A38-FAB89818288F@gmx.de> <2148E2EF-A119-4499-BAC1-7E647C53F077@gmx.de> <03951E31-8F11-4FB8-9558-29EAAE3DAE4D@gmx.de> To: Dave Taht X-Mailer: Apple Mail (2.1508) X-Provags-ID: V03:K0:CR4yjaPhK+ohIxGkggSggSKHRFNprq4agBCgZMvJULUNRyU7F2c 7q8MwwEa8S7VWIV3uCPcEUuPdYGtnNhDpNIFVnwEj7lFVmOTtlIBw3RKn07qpFwdlvB+zjG DgMVp/DFd+PwnlaAsKpodFo0yf86Zcnij2Te6et29XtpbUpfbAXkFlaAOrnPKrtmUJUrJIl rLvkhB5QGdnGaciwiqzNQ== Cc: cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] some kernel updates 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: Sat, 24 Aug 2013 23:08:16 -0000 Hi Dave, so I git around to do the PIE tests... On Aug 23, 2013, at 07:13 , Dave Taht wrote: >=20 >=20 >=20 > On Thu, Aug 22, 2013 at 5:52 PM, Sebastian Moeller = wrote: > Hi List, hi Jesper, >=20 > So I tested 3.10.9-1 to assess the status of the HTB atm link layer = adjustments to see whether the recent changes resurrected this feature. > Unfortunately the htb_private link layer adjustments still is = broken (RRUL ping RTT against Toke's netperf host in Germany of ~80ms, = same as without link layer adjustments). On the bright side the tc_stab = method still works as well as before (ping RTT around 40ms). > I would like to humbly propose to use the tc stab method in = cerowrt to perform ATM link layer adjustments as default. To repeat = myself, simply telling the kernel a lie about the packet size seems more = robust than fudging HTB's rate tables. Especially since the kernel = already fudges the packet size to account for the ethernet header and = then some, so this path should receive more scrutiny by virtue of having = more users? >=20 > It's my hope that the atm code works but is misconfigured. You can = output the tc commands by overriding the TC variable with TC=3D"echo tc" = and paste here. > =20 > Now, I have been testing this using Dave's most recent cerowrt = alpha version with a 3.10.9 kernel on mips hardware, I think this kernel = should contain all htb fixes including commit 8a8e3d84b17 (net_sched: = restore "linklayer atm" handling) but am not fully sure. >=20 > It does.=20 > =20 > `@Dave is there an easy way to find which patches you applied to the = kernels of the cerowrt (testing-)releases? >=20 > Normally I DO commit stuff that is in testing, but my big push this = time around was to get everything important into mainline 3.10, as it = will be the "stable" release for a good long time.=20 > =20 > So I am still mostly working the x86 side at the moment. I WAS kind of = hoping that everything I just landed would make it up to 3.10. But for = your perusal: >=20 > http://snapon.lab.bufferbloat.net/~cero2/patches/3.10.9-1/ has most of = the kernel patches I used in it. 3.10.9-2 has the ipv6subtrees patch = ripped out due to another weird bug I'm looking at. (It also has support = for ipv6 nat thx to the ever prolific stephen walker heeding the call = for patches...). 100% totally untested, I have this weird bug to figure = out how to fix next: >=20 > = http://lists.alioth.debian.org/pipermail/babel-users/2013-August/001419.ht= ml >=20 > I fear it's a comparison gone south, maybe in bradley's optimizations = for not kernel trapping, don't know. >=20 > 3.10.9-2 also disables dnsmasq's dhcpv6 in favor of 6relayd. I HATE = losing the close naming integration, but, had to try this.... >=20 > If you guys want me to start committing and pushing patches again, = I'll do it, but most of that stuff will end up in 3.10.10, I think, in a = couple days. The rest might make 3.12. Pie has to survive scrutiny on = the netdev list in particular. >=20 > While I have you r attention :) I also tested 3.10.9-1's pie and it is = way better than 3.10.6-1's (RRUL ping RTTs around 110 ms instead of = 3000ms) but still worse than fq_codel (ping RTTs around 40ms with proper = atm link layer adjustments). >=20 > This is with simple.qos I imagine? Simplest should do better than that = with pie. Judging from how its estimator works I think it will do badly = with multiple queues. But testing will tell... >=20 > But, yea, this pie is actually usable, and the previous wasn't. Thank = you for looking at it! >=20 > It is different from cisco's last pie drop in that it can do ecn, does = local congestion notification, has a better use of net_random, it's = mostly KernelStyle, and I forget what else. >=20 > There is still a major rounding error in the code, and I'd like cisco = to fix the api so it uses identical syntax to codel. Right now you = specify "target 8" to get "target 7", and the "ms" is implied. target 5 = becomes target 3. This is as confusing as it is funny=85. > The default target is a whopping 20 (rounded to 19), which is in part = where your 70+ms of extra delay came from.=20 >=20 > Multiple parties have the delusion that 20ms is "good enough". It certainly is better than nothing, if the hardware does not = allow codel=85, but it is not like changing target has that big an = effect on RRUL ping RTT: AQM nominal target[ms] estimated ping RTT[ms] down avg = good-put[Mbits/s] up avg good-put[Mbits/s] pie 20 110 = 2.8 = 0.4 pie 8 100 = 2.7 = 0.41 pie 5 90 = 2.7 = 0.4 so the target does not have very strong effect on the pie latency... ns2_codel 7 50 = 3.1 = 0.39 ns2_codel 3 45 = 3.1 = 0.37 fq_codel 7 39 = 3.1 = 0.38 fq_codel 3 38 = 3.15 = 0.38 Nor does it have a big effect on codel. But latency-wise, I agree, the codels are in a league of their own. And = pie sacrifices more down good-put than codel, but seems to retain a bit = more of the up good-put. I hope the fraction of routers that can only = ever do PIE is not too large, codel looks like the better solution=85 (I am happy to share my plots but due to email size issues I will not = attach them without someone asking) >=20 > Part of the remaining delay may also be rounding error. Cisco uses = kernels with HZ=3D1000, cero uses HZ=3D250..... >=20 > Anyway, to get more comparable tests... you can fiddle with the two = $QDISC lines in simple*.qos to add a target 8 to get closer to a codel = 5ms config, but that would break a codel config which treats target 8 as = target 8us. >=20 > I MIGHT, if I get energetic enough, fix the API, the time accounting, = and a few other things in pie, the problem is, that ns2_codel seems = still more effective on most workloads and *fq_codel smokes absolutely = everything. There are a few places where pie is a win over straight = codel, notably on packet floods. And it may well be easier to retrofit = into existing hardware fast path designs.=20 >=20 > I worry about interactions between pie and other stuff. It seems = inevitable at this point that some form of pie will be widely deployed, = and I simply haven't tried enough traffic types and RTTs to draw a firm = conclusion, period. Long RTTs are the last big place where codel and pie = and fq_codel have to be seriously tested.=20 >=20 > ns2_codel is looking pretty good now, at the shorter RTTs I've tried. = A big problem I have is getting decent long RTT emulation out of netem = (some preliminary code is up at github)=20 >=20 > ... and getting cero stable enough for others to actually use - next = up is fixing the userspace problems.=20 >=20 > ... and trying to make a small dent in the wifi problem along the way = (couple commits coming up) >=20 > ... and find funding to get through the winter. > =20 > There's probably a few other things that are on that list but I = forget. Oh, yea, since the aqm wg was voted on to be formed, I decided I = could quit smoking. > =20 > While I am not able to build kernels, it seems that I am able to = quickly test whether link layer adjustments work or not. SO aim happy to = help where I can :) >=20 > Give pie target 8 and target 5 a shot, please? ns2_codel target 3ms = and target 7ms, too. fq_codel, same.... > =20 > tc -s qdisc show dev ge00 > tc -s qdisc show dev ifb0 >=20 > would be useful info to have in general after each test. So I took these and can post if you are interested. BTW so far I = did not bother to save the actual netsurf-wrapper data, all I keep are = the plots (as I am somewhat tight on disk space for my day job), since I = do not think I will try further analysis on the data (yet). Best Sebastian >=20 > TIA. >=20 > There are also things like tcp_upload and tcp_download and = tcp_bidirectional that are useful tests in the rrul suite. >=20 > Thank you for your efforts on these early alpha releases. I hope = things will stablize more soon, and I'll fold your aqm stuff into my = next attempt this weekend. >=20 > This is some of the stuff I know that needs fixing in userspace: >=20 > * TODO readlink not found > * TODO netdev user missing > * TODO Wed Dec 5 17:14:46 2012 authpriv.error dnsmasq: found already = running DHCP-server on interface 'se00' refusing to start, use 'option = force 1' to override > * TODO [ 18.480468] Mirror/redirect action on > [ 18.539062] Failed to load ipt action > * upload and download are reversed in aqm > * BCP38 > * Squash CS values > * Replace ntp > * Make ahcp client mode > * Drop more privs for polipo > * upnp > * priv separation > * Review FW rules > * dhcpv6 support > * uci-defaults/make-cert.sh uses a bad path for px5g > * Doesn't configure the web browser either >=20 >=20 >=20 >=20 > Best > Sebastian >=20 >=20 >=20 >=20 > --=20 > Dave T=E4ht >=20 > Fixing bufferbloat with cerowrt: = http://www.teklibre.com/cerowrt/subscribe.html