From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-x132.google.com (mail-il1-x132.google.com [IPv6:2607:f8b0:4864:20::132]) (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 177F93CB38 for ; Mon, 3 Jan 2022 01:44:09 -0500 (EST) Received: by mail-il1-x132.google.com with SMTP id 9so8550538ill.9 for ; Sun, 02 Jan 2022 22:44:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :content-transfer-encoding; bh=3qGl5jYKQ5mkvZLKXiJd3YdLHXIdKLejcmu6GLD03C0=; b=LwlCcfOQSYFnTxo2ONvzP36vfOabqmSF9utYQEcsWDUODcR16xfleu14x+Y8ClXYMF 5bgttVkHl4qmdWeYKjMLINkTYsk9PZ4UgkD3WjZIV5wERkY1h+v5C6xg/MYpNF0ipuij PArWRZRuvI/Wk7qPj41RauW9Tch7y71+Oy5NDmCCsGOr282iQDHgGijozfiE+Klnbdpr sCx+oBQ4/rtE1fhE7OSyMmD2aahZANeYilqbhHnwI9c8UFjQJT59FFPf7QUEMPirO20c +3fbNSRXA3kxM7wTJu4NXO1RSqj1fvlMlEqQDctzUYru7N3SlZZpABm9OxRkuFFoUTeF XwTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:content-transfer-encoding; bh=3qGl5jYKQ5mkvZLKXiJd3YdLHXIdKLejcmu6GLD03C0=; b=VdER6WVzN5gBXzkflBnGiLcKhOiBlX0lGJFvtQGPersZhnXnOitqTH1ZhGMVwKSh85 2Iu8xYtkyvJG3FqIuMnNLFov95tU1DEKEQMwr3b+V1x6CwyHWyhagoAfIfWQXEgqJCOc zeQU/B4uw5O37DGGp4wv8rRFH4XcxOE86KDsQ+db+0d0zWFZUCgRK/XN2NVlP79OUfQM eRjorZPmQe6Dd17xXVo0nSgVLRwhQwPH7fU7mQlKkWaQUnM/xdcYBP+cVtSeT7avTlNP lJ5a774ZbwFslH1hc84FT2hWXl1xRRRYCpF8/4+d8YazmEmM/1AimF8gYbvtdgnquhOh KSvg== X-Gm-Message-State: AOAM532Ks1dby4HjgKNkA4XGrl1hKILCHlt8hfJ5GFSXZx9upl8y25/f FZzW9J5Dd96R5FG1FE6ezfTiLkm/xWCVXn6TkvxGxbyB X-Google-Smtp-Source: ABdhPJwvW7g/sGDFddcs2zON5L1Z6mjIk7Y1WStn+kUdFRK5v6LwiRAeGNrOdcteBlp7C3ZX9vklxF0MuERDEJ4mLDA= X-Received: by 2002:a05:6e02:1ca9:: with SMTP id x9mr19937836ill.283.1641192248235; Sun, 02 Jan 2022 22:44:08 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Sun, 2 Jan 2022 22:43:55 -0800 Message-ID: To: bloat Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: [Bloat] Fwd: fq_codel in debian X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 03 Jan 2022 06:44:09 -0000 debian finally adopts fq_codel. ---------- Forwarded message --------- From: Noah Meyerhans Date: Sun, Jan 2, 2022 at 9:30 PM Subject: Re: fq_codel in debian To: Dave Taht The change was merged; Barring any regressions or the like, the fq_codel should be the default for future major releases of Debian. Happy New Year. noah On Wed, Nov 17, 2021 at 09:25:43AM -0800, Dave Taht wrote: > Well, I hope it makes it in before then. But happy to hear it's on it's w= ay! > > I've been working at the us government policy level lately. Attached > is a draft report we're working on in BITAG. I'd like to find some way > to improve it, with an axe, if you are interested in a quick review. > > On Wed, Nov 17, 2021 at 9:20 AM Noah Meyerhans wrote: > > > > Sadly not in time for the Debian 11 release. So, we've got to wait > > until Debian 12, which is likely going to be released mid 2023. > > > > On Mon, Nov 15, 2021 at 10:11:34AM -0800, Dave Taht wrote: > > > you ever get anywhere? > > > > > > On Sat, Jan 23, 2021 at 2:33 PM Dave Taht wrote= : > > > > > > > > On Thu, Jan 21, 2021 at 4:22 PM Noah Meyerhans w= rote: > > > > > > > > > > On Wed, Jan 20, 2021 at 10:47:42PM -0800, Dave Taht wrote: > > > > > > I'm not on that debian list, but I'm glad to hear of your patch= . In > > > > > > particular, on the armbian releases for a zillion low end arms, > > > > > > fq_codel is often not even built, although made the default by > > > > > > systemd, so my hope is your patch will fix that, and pfifo_fast= will > > > > > > continue to die the death it deserves. > > > > > > > > > > It may help with these, although it's not a given since they all = provide > > > > > their own kernels with their own configuration. It's probably st= ill > > > > > necessary to chase down the maintainers and make sure they do the= right > > > > > thing. > > > > > > > > Yes, I figured we should make that effort, but perhaps after your p= atch > > > > goes through it would be easier. I am a big proponent of testing, > > > > and some of those low end arches might not have a fast onboard > > > > clock for timestamps. > > > > > > > > > > > > > > > I wish cake wasn't so heavyweight, it pretty much solved everyt= hing > > > > > > even slightly wrong with fq_codel. > > > > > > > > > > It's been suggested that we also consider pie, which can be enabl= ed as a > > > > > default qdisc in Linux. Do you have a sense of how suitable it w= ould be > > > > > versus fq_codel and cake? > > > > > > > > How long an answer do you want? :) I can write something for wider = consumption > > > > > > > > but I can go on record with this... > > > > > > > > as one of the authors of codel/fq_codel I could be considered biase= d... except > > > > that I also worked pretty hard on pie and several other variants, l= ike > > > > sfqred. fq_codel > > > > swept them all off the map and I'm pretty proud of the one in wifi > > > > also ( https://lwn.net/Articles/705884/ ). > > > > > > > > The newer "Cake" addressed a few new things that the sqm subsystem = we > > > > built around fq-codel really beautifully, > > > > but it's too slow to use as a default on higher speed links. fq_cod= el > > > > is massively better than > > > > pfifo_fast in all respects. > > > > > > > > My principal reason for working on the alternative ideas in pie was > > > > that I was afraid > > > > that in some future day someone would find an attack on codel, and = I > > > > preferred a diverse > > > > ecosystem. Also I viewed pie as slightly easier to implement in pur= e > > > > hw as it was closer > > > > to red in design, and O(1). In software or firmware the difference = in > > > > cpu cost is immeasurable. Also > > > > I wanted to produce fair, and comprehensive benchmarks. Which we di= d. > > > > And the pie makers > > > > still haven't. > > > > > > > > I have stated elsewhere that pie is a better "single queue" AQM tha= n codel is. > > > > It is less gentle, and more responsive to overload. > > > > codel is kinder and gentler but: generally achieves queue lengths m= uch shorter > > > > than pie can. Pie is also kind of unstable on jittery links, like > > > > wifi. Adding fq to codel > > > > was a marriage made in heaven, it lets codel be gentle everywhere n= eeded, and > > > > fq prioritize sparser flows. > > > > > > > > fq, or fq-anything is VASTLY better than any single queue aqm can b= e. > > > > A single unresponsive sender > > > > can completely disable pfifo-fast, pie, codel, red or what have you= , > > > > while fq or fq-anything > > > > just shrugs it off. A lot of good things that are also good on cpu = in > > > > this sadly common case, > > > > is the bulk drop facility in fq-codel. fq-codel and fq-pie achieve > > > > near perfect utilization > > > > for multiple flows, which a single queue aqm cannot. > > > > > > > > As for fq-pie vs fq-codel, the authors of fq-pie maintain it is bet= ter > > > > for DASH traffic, > > > > and I maintain that fq-codel is better for all forms of other traff= ic. > > > > There's a couple > > > > competing papers on this. Codel's head drop (+bql) is very superior= to > > > > tail drop in every > > > > circumstance, you (almost) never, for example, get a TCP RTO, and s= horter > > > > queues make the impact of a hash collission much less. > > > > > > > > (that said, cake uses a set associative rather than direct mapped h= ash, can > > > > do per host/per flow fq even through nat, has a native shaper that = works > > > > to defeat an bad htb shaper upstream of it, does dscp classificatio= n > > > > and ack-filtering, > > > > and can be configured with a single line of tc.) If we could someho= w have > > > > achieved those goals without eating at least 3x more cpu than fq_co= del > > > > does... I'd have > > > > loved to have made it the linux default... but we didn't. > > > > > > > > We wrote a couple good papers on cake, and it's gradually becoming = the > > > > default sqm implementation for many a router OS. > > > > > > > > Anyway... > > > > > > > > It's taken 8 years for fq-pie to become even slightly competetive w= ith > > > > fq_codel, with > > > > continuous refinement, where fq_codel is stable, well tested, and d= etermistic in > > > > action rather than random, and heavily deployed since 2012. > > > > > > > > OFF THE RECORD: > > > > > > > > The pie folk tend to be really shrill sometimes, and in general I f= ind > > > > their papers > > > > rather weak and too narrowly focused in scope. They almost never pu= blish > > > > source code to their benchmarks, either. And: There's a subcontinge= nt > > > > ranting about L4S vs SCE which is one of the saddest poltical fight= s I've > > > > ever been in ni the ietf. But I digress. > > > > > > > > > > > > > > > have a gratuitous yet funny link. > > > > > > > > > > > > https://blog.apnic.net/2020/01/22/bufferbloat-may-be-solved-but= -its-not-over-yet/ > > > > > > > > > > Thanks, that was fun! > > > > > > > > Glad I could share. Pass it on. I only give one talk a year, and > > > > post-covid, I don't think > > > > I'll ever be able "push packets" like that around again. > > > > > > > > > > > > > > > > happy new year. > > > > > > > > > > > > > > > > And same to you. > > > > > > > > > > noah > > > > > > > > > > > > > > > > > -- > > > > "For a successful technology, reality must take precedence over pub= lic > > > > relations, for Mother Nature cannot be fooled" - Richard Feynman > > > > > > > > dave@taht.net CTO, TekLibre, LLC Tel: 1-831-435-07= 29 > > > > > > > > > > > > --=20 I tried to build a better future, a few times: https://wayforward.archive.org/?site=3Dhttps%3A%2F%2Fwww.icei.org Dave T=C3=A4ht CEO, TekLibre, LLC