netdev - Re: [PATCH iproute2-next 0/2] Add support for the ETS Qdisc

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Date:   Sat, 18 Jan 2020 14:58:27 -0700
From:   David Ahern <dsahern@...il.com>
To:     Petr Machata <pmachata@...il.com>, netdev@...r.kernel.org
Cc:     David Ahern <dsahern@...il.com>, Ido Schimmel <idosch@...lanox.com>
Subject: Re: [PATCH iproute2-next 0/2] Add support for the ETS Qdisc

On 1/13/20 7:16 AM, Petr Machata wrote:
> A new Qdisc, "ETS", has been accepted into Linux at kernel commit
> 6bff00170277 ("Merge branch 'ETS-qdisc'"). Add iproute2 support for this
> Qdisc.
> 
> Patch #1, changes libnetlink to admit NLA_F_NESTED in nested attributes.
> Patch #2 then adds ETS support as such.
> 
> Examples (taken from the kernel patchset):
> 
> - Add a Qdisc with 6 bands, 3 strict and 3 ETS with 45%-30%-25% weights:
> 
>     # tc qdisc add dev swp1 root handle 1: \
> 	ets strict 3 quanta 4500 3000 2500 priomap 0 1 1 1 2 3 4 5
>     # tc qdisc sh dev swp1
>     qdisc ets 1: root refcnt 2 bands 6 strict 3 quanta 4500 3000 2500 priomap 0 1 1 1 2 3 4 5 5 5 5 5 5 5 5 5 
> 
> - Tweak quantum of one of the classes of the previous Qdisc:
> 
>     # tc class ch dev swp1 classid 1:4 ets quantum 1000
>     # tc qdisc sh dev swp1
>     qdisc ets 1: root refcnt 2 bands 6 strict 3 quanta 1000 3000 2500 priomap 0 1 1 1 2 3 4 5 5 5 5 5 5 5 5 5 
>     # tc class ch dev swp1 classid 1:3 ets quantum 1000
>     Error: Strict bands do not have a configurable quantum.
> 
> - Purely strict Qdisc with 1:1 mapping between priorities and TCs:
> 
>     # tc qdisc add dev swp1 root handle 1: \
> 	ets strict 8 priomap 7 6 5 4 3 2 1 0
>     # tc qdisc sh dev swp1
>     qdisc ets 1: root refcnt 2 bands 8 strict 8 priomap 7 6 5 4 3 2 1 0 7 7 7 7 7 7 7 7 
> 
> - Use "bands" to specify number of bands explicitly. Underspecified bands
>   are implicitly ETS and their quantum is taken from MTU. The following
>   thus gives each band the same weight:
> 
>     # tc qdisc add dev swp1 root handle 1: \
> 	ets bands 8 priomap 7 6 5 4 3 2 1 0
>     # tc qdisc sh dev swp1
>     qdisc ets 1: root refcnt 2 bands 8 quanta 1514 1514 1514 1514 1514 1514 1514 1514 priomap 7 6 5 4 3 2 1 0 7 7 7 7 7 7 7 7 
> 

applied to iproute2-next. Thanks for putting a lot of examples in the
cover letter.