netdev - Re: Unable to create htb tc classes more than 64K

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Date:   Tue, 27 Aug 2019 14:41:05 -0700
From:   Dave Taht <dave.taht@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Akshat Kakkar <akshat.1984@...il.com>,
        Anton Danilov <littlesmilingcloud@...il.com>,
        NetFilter <netfilter-devel@...r.kernel.org>,
        lartc <lartc@...r.kernel.org>, netdev <netdev@...r.kernel.org>,
        bloat <bloat@...ts.bufferbloat.net>
Subject: Re: Unable to create htb tc classes more than 64K

On Tue, Aug 27, 2019 at 2:09 PM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
>
> On 8/27/19 10:53 PM, Dave Taht wrote:
> >
> > Although this is very cool, I think in this case the OP is being
> > a router, not server?
>
> This mechanism is generic. EDT has not been designed for servers only.
>
> One HTB class (with one associated qdisc per leaf) per rate limiter
> does not scale, and consumes a _lot_ more memory.
>
> We have abandoned HTB at Google for these reasons.
>
> Nice thing with EDT is that you can stack arbitrary number of rate limiters,
> and still keep a single queue (in FQ or another layer downstream)

There's a lot of nice things about EDT! I'd followed along on the
theory, timerwheels, virtual clocks, etc, and went
seeking ethernet hw that could do it (directly) on the low end and
came up empty - and doing anything with the concept required a
complete rethink on everything we were already doing in
wifi/fq_codel/cake ;(, and after we shipped cake in 4.19, I bought a
sailboat, and logged out for a while.

The biggest problem bufferbloat.net has left is more efficient inbound
shaping/policing on cheap hw.

I don't suppose you've solved that already? :puppy dog eyes:

Next year's version of openwrt we can maybe try to do something
coherent with EDT.

>

-- 

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-831-205-9740