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Groups > linux.debian.kernel > #66874

Bug#890343: linux: make fq_codel default for default_qdisc

Cross-posted to 2 groups.

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On 4/23/20 4:24 PM, Noah Meyerhans wrote:
> On Thu, Apr 23, 2020 at 03:34:06PM -0700, Matt Taggart wrote:
>> fq_codel is better in every way than pfifo_fast and I am unaware of any
>> reason why it would not be a better default. (but don't trust me, ask the
>> kernel networking experts)
> 
> Isn't CAKE supposed to be even better than fq_codel, including better
> handling of both large numbers of flows (e.g. busy routers) and small
> systems with limited resources.
> 
> https://www.bufferbloat.net/projects/codel/wiki/Cake/
> 
> If we consider a change (which I think we should), is there a reason we
> wouldn't go with CAKE?

In net/sched/Kconfig, the options for NET_SCH_DEFAULT are:
  fq, codel, fq_codel, sfq, pfifo_fast

Also Documentation/admin-guide/sysctl/net.rst explains:

   default_qdisc
   -------------

   The default queuing discipline to use for network devices. This allows
   overriding the default of pfifo_fast with an alternative. Since the 

   default queuing discipline is created without additional parameters so
   is best suited to queuing disciplines that work well without
   configuration like stochastic fair queue (sfq), CoDel (codel) or fair
   queue CoDel (fq_codel). Don't use queuing disciplines like
   Hierarchical Token Bucket or Deficit Round Robin which require setting
   up classes and bandwidths. Note that physical multiqueue interfaces
   still use mq as root qdisc, which in turn uses this default for its
   leaves. Virtual devices (like e.g. lo or veth) ignore this setting and
   instead default to noqueue.

CAKE, while better for AQM, requires interface specific parameters and 
so won't work for a default (and also is generally used in conjunction 
with fq_codel)

-- 
Matt Taggart
taggart@debian.org

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Thread

Bug#890343: linux: make fq_codel default for default_qdisc Matt Taggart <taggart@debian.org> - 2020-04-24 00:40 +0200
  Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2020-04-24 01:30 +0200
    Bug#890343: linux: make fq_codel default for default_qdisc Matt Taggart <taggart@debian.org> - 2020-04-24 07:10 +0200
  Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2021-01-08 01:20 +0100
    Bug#890343: linux: make fq_codel default for default_qdisc Ivan Baldo <ibaldo@adinet.com.uy> - 2021-01-18 02:40 +0100
      Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2021-01-20 23:00 +0100
    Bug#890343: linux: make fq_codel default for default_qdisc Vincent Blut <vincent.debian@free.fr> - 2021-01-20 22:30 +0100
      Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2021-01-20 23:10 +0100
        Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2021-01-20 23:30 +0100
          Processed: Re: Bug#890343: linux: make fq_codel default for  default_qdisc "Debian Bug Tracking System" <owner@bugs.debian.org> - 2021-01-20 23:30 +0100
        Bug#890343: linux: make fq_codel default for default_qdisc Vincent Blut <vincent.debian@free.fr> - 2021-01-20 23:50 +0100
          Bug#890343: linux: make fq_codel default for default_qdisc Noah Meyerhans <noahm@debian.org> - 2021-01-21 00:00 +0100
            Bug#890343: linux: make fq_codel default for default_qdisc Vincent Blut <vincent.debian@free.fr> - 2021-01-21 00:10 +0100
            Bug#890343: linux: make fq_codel default for default_qdisc Ben Hutchings <ben@decadent.org.uk> - 2021-01-21 00:50 +0100
              Bug#890343: linux: make fq_codel default for default_qdisc Vincent Blut <vincent.debian@free.fr> - 2021-02-26 19:10 +0100

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