netdev - Re: [PATCH net-next v6] Add Common Applications Kept Enhanced (cake) qdisc

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Date:   Mon, 30 Apr 2018 14:21:06 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Toke Høiland-Jørgensen <toke@...e.dk>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        cake@...ts.bufferbloat.net, Dave Taht <dave.taht@...il.com>
Subject: Re: [PATCH net-next v6] Add Common Applications Kept Enhanced (cake) qdisc

On Sun, Apr 29, 2018 at 2:34 PM, Toke Høiland-Jørgensen <toke@...e.dk> wrote:
> 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.

Why this TCP ACK filtering has to be built into CAKE qdisc rather than
an independent TC filter? Why other qdisc's can't use it?


> * 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
>

Thanks.