[Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Dave Taht]

cbs shaper...


---------- Forwarded message ----------
From: Stephen Hemminger <stephen@networkplumber.org>
Date: Wed, Nov 1, 2017 at 2:24 PM
Subject: Re: [iproute2 1/2] tc: Add support for the CBS qdisc
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: davem@davemloft.net, Vinicius Costa Gomes
<vinicius.gomes@intel.com>, netdev@vger.kernel.org,
nhorman@redhat.com, sassmann@redhat.com, jogreene@redhat.com


On Thu, 26 Oct 2017 10:17:48 -0700
Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
>
> The Credit Based Shaper (CBS) queueing discipline allows bandwidth
> reservation with sub-milisecond precision. It is defined by the
> 802.1Q-2014 specification (section 8.6.8.2 and Annex L).
>
> The syntax is:
>
> tc qdisc add dev DEV parent NODE cbs locredit <LOCREDIT>
>               hicredit <HICREDIT> sendslope <SENDSLOPE>
>               idleslope <IDLESLOPE>
>
> (The order is not important)
>
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied to net-next branch (now that CBS is upstream in kernel).



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619

Re: [Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Jonathan Morton]

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The name is certainly intriguing, but just look at all those parameters!
Cake's shaper doesn't need them.

- Jonathan Morton

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Re: [Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Dave Taht]

Jonathan Morton <chromatix99@gmail.com> writes:

> The name is certainly intriguing, but just look at all those parameters! Cake's
> shaper doesn't need them.

It's a "standard". I'd rather like to benchmark that vs cake in terms of
cpu and effectiveness.

>
> - Jonathan Morton
>
>
> _______________________________________________
> Cake mailing list
> Cake@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake

Re: [Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Jonathan Morton]

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I looked up how it's supposed to work.

Seems like it relies on a fixed bandwidth underlying link, and piggybacks
on its clocks to maintain the associated state in realtime.  Obviously
designed to be implemented in hardware using an adder and an accumulator,
rather than on a CPU.

The parameters required are a direct reflection of what such hardware
requires, and are not at all user friendly.

- Jonathan Morton

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Re: [Cake] Fwd: [iproute2 1/2] tc: Add support for the CBS qdisc

[Dave Taht]

Jonathan Morton <chromatix99@gmail.com> writes:

> I looked up how it's supposed to work.
>
> Seems like it relies on a fixed bandwidth underlying link, and piggybacks on its
> clocks to maintain the associated state in realtime. Obviously designed to be
> implemented in hardware using an adder and an accumulator, rather than
> on a CPU.
>
> The parameters required are a direct reflection of what such hardware requires,
> and are not at all user friendly.

Well, having just heard of it, I'm building it as part of my next build
of net-next.

I would certainly like to be able to pour much of cake into hardware. We've
got billions of spare transistors nowadays....

> - Jonathan Morton