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  1. Jul 11, 2018
    • Toke Høiland-Jørgensen's avatar
      sched: Add Common Applications Kept Enhanced (cake) qdisc · 046f6fd5
      Toke Høiland-Jørgensen authored
      sch_cake targets the home router use case and is intended to squeeze the
      most bandwidth and latency out of even the slowest ISP links and routers,
      while presenting an API simple enough that even an ISP can configure it.
      
      Example of use on a cable ISP uplink:
      
      tc qdisc add dev eth0 cake bandwidth 20Mbit nat docsis ack-filter
      
      To shape a cable download link (ifb and tc-mirred setup elided)
      
      tc qdisc add dev ifb0 cake bandwidth 200mbit nat docsis ingress wash
      
      CAKE is filled with:
      
      * A hybrid Codel/Blue AQM algorithm, "Cobalt", tied to an FQ_Codel
        derived Flow Queuing system, which autoconfigures based on the bandwidth.
      * A novel "triple-isolate" mode (the default) which balances per-host
        and per-flow FQ even through NAT.
      * An deficit based shaper, that can also be used in an unlimited mode.
      * 8 way set associative hashing to reduce flow collisions to a minimum.
      * A reasonable interpretation of various diffserv latency/loss tradeoffs.
      * Support for zeroing diffserv markings for entering and exiting traffic.
      * Support for interacting well with Docsis 3.0 shaper framing.
      * Extensive support for DSL framing types.
      * Support for ack filtering.
      * Extensive statistics for measuring, loss, ecn markings, latency
        variation.
      
      A paper describing the design of CAKE is available at
      https://arxiv.org/abs/1804.07617
      
      , and will be published at the 2018 IEEE
      International Symposium on Local and Metropolitan Area Networks (LANMAN).
      
      This patch adds the base shaper and packet scheduler, while subsequent
      commits add the optional (configurable) features. The full userspace API
      and most data structures are included in this commit, but options not
      understood in the base version will be ignored.
      
      Various versions baking have been available as an out of tree build for
      kernel versions going back to 3.10, as the embedded router world has been
      running a few years behind mainline Linux. A stable version has been
      generally available on lede-17.01 and later.
      
      sch_cake replaces a combination of iptables, tc filter, htb and fq_codel
      in the sqm-scripts, with sane defaults and vastly simpler configuration.
      
      CAKE's principal author is Jonathan Morton, with contributions from
      Kevin Darbyshire-Bryant, Toke Høiland-Jørgensen, Sebastian Moeller,
      Ryan Mounce, Tony Ambardar, Dean Scarff, Nils Andreas Svee, Dave Täht,
      and Loganaden Velvindron.
      
      Testing from Pete Heist, Georgios Amanakis, and the many other members of
      the cake@lists.bufferbloat.net mailing list.
      
      tc -s qdisc show dev eth2
       qdisc cake 8017: root refcnt 2 bandwidth 1Gbit diffserv3 triple-isolate split-gso rtt 100.0ms noatm overhead 38 mpu 84
       Sent 51504294511 bytes 37724591 pkt (dropped 6, overlimits 64958695 requeues 12)
        backlog 0b 0p requeues 12
        memory used: 1053008b of 15140Kb
        capacity estimate: 970Mbit
        min/max network layer size:           28 /    1500
        min/max overhead-adjusted size:       84 /    1538
        average network hdr offset:           14
                          Bulk  Best Effort        Voice
         thresh      62500Kbit        1Gbit      250Mbit
         target          5.0ms        5.0ms        5.0ms
         interval      100.0ms      100.0ms      100.0ms
         pk_delay          5us          5us          6us
         av_delay          3us          2us          2us
         sp_delay          2us          1us          1us
         backlog            0b           0b           0b
         pkts          3164050     25030267      9530280
         bytes      3227519915  35396974782  12879808898
         way_inds            0            8            0
         way_miss           21          366           25
         way_cols            0            0            0
         drops               5            0            1
         marks               0            0            0
         ack_drop            0            0            0
         sp_flows            1            3            0
         bk_flows            0            1            1
         un_flows            0            0            0
         max_len         68130        68130        68130
      
      Tested-by: default avatarPete Heist <peteheist@gmail.com>
      Tested-by: default avatarGeorgios Amanakis <gamanakis@gmail.com>
      Signed-off-by: default avatarDave Taht <dave.taht@gmail.com>
      Signed-off-by: default avatarToke Høiland-Jørgensen <toke@toke.dk>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      046f6fd5
  2. Jul 09, 2018
  3. Jul 08, 2018
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