[Cake] Advantages to tightly tuning latency

Luca Muscariello muscariello at ieee.org
Wed Apr 22 05:03:53 EDT 2020


On Wed, Apr 22, 2020 at 12:44 AM Dave Taht <dave.taht at gmail.com> wrote:

> On Tue, Apr 21, 2020 at 3:33 PM Jonathan Morton <chromatix99 at gmail.com>
> wrote:
> >
> > > On 22 Apr, 2020, at 1:25 am, Thibaut <hacks at slashdirt.org> wrote:
> > >
> > > My curiosity is piqued. Can you elaborate on this? What does free.fr
> do?
> >
> > They're a large French ISP.  They made their own CPE devices, and
> debloated both them and their network quite a while ago.  In that sense, at
> least, they're a model for others to follow - but few have.
> >
> >  - Jonathan Morton
>
> they are one of the few ISPs that insisted on getting full source code
> to their DSL stack, and retained the chops to be able to modify it. I
> really admire their revolution v6 product. First introduced in 2010,
> it's been continuously updated, did ipv6 at the outset, got fq_codel
> when it first came out, and they update the kernel regularly. All
> kinds of great features on it, and ecn is enabled by default for those
> also (things like samba). over 3 million boxes now I hear....
>
> with <1ms of delay in the dsl driver, they don't need to shape, they
> just run at line rate using three tiers of DRR that look a lot like
> cake. They shared their config with me, and before I lost heart for
> future internet drafts, I'd stuck it here:
>
>
> https://github.com/dtaht/bufferbloat-rfcs/blob/master/home_gateway_queue_management/middle.mkd
>
> Occasionally they share some data with me. Sometimes I wish I lived in
> paris just so I could have good internet! (their fiber offering is
> reasonably buffered (not fq_codeled) and the wifi... maybe I can get
> them to talk about what they did)
>
> When free.fr shipped fq_codel 2 months after we finalized it, I
> figured the rest of the world was only months behind. How hard is it
> to add 50 lines of BQL oriented code to a DSL firmware?
>
>
Free has been using SFQ since 2005 (if I remember well).
They announced the wide deployment of SFQ in the free.fr newsgroup.
Wi-Fi in the free.fr router was not as good though.

In Paris there is a lot of GPON now that is replacing DSL. But there is
a nation-wide effort funded by local administrations to get fiber
everywhere. There are small towns in the countryside with fiber.
Public money has made, and is making that possible.
There is still a little of Euro-DOCSIS, but frankly compared to fiber
it has no chance to survive.

I currently have 2Gbps/600Mbps access with orange.fr and free.fr has a
subscription
at 10Gbps GPON. I won't tell you the price because you may feel depressed
compared to other countries where prices are much higher.

The challenge becomes to keep up with these link rates in software
as there is a lot of hardware offloading.

As soon as 802.11ax becomes the norm, software scheduling will become
a challenge.

Luca
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