Re: [RFC] Packet pacing (offload) for flow-aggregates and forwarding use-cases

[Eric Dumazet <eric.dumazet@gmail.com>]

On 3/24/20 12:05 PM, Yossi Kuperman wrote:
> Hello,
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>  
> 
> We would like to support a forwarding use-case in which flows are classified and paced
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> according to the selected class. For example, a packet arrives at the ingress hook of interface
> 
> eth0,  performing a sequence of filters and being redirected to interface eth1. Pacing takes
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> place at the egress qdisc of eth1.
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>  
> 
> FQ queuing discipline is classless and cannot provide such functionality. Each flow is
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> paced independently, and different pacing is only configurable via a socket-option—less
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> suitable for forwarding  use-case.
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>  
> 
> It is worth noting that although this functionality might be implemented by stacking multiple
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> queuing disciplines, it will be very difficult to offload to hardware.
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>  
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> We propose introducing yet another classful qdisc, where the user can specify in advance the
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> desired classes (i.e. pacing) and provide filters to classify flows accordingly. Similar to other
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> qdiscs, if skb->priority is already set, we can skip the classification; useful for forwarding
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> use-case, as the user can set the priority field in ingress. Works nicely with OVS/TC.
> 
>  
> 
> Any thoughts please?
> 

Why not using HTB for this typical use case ?