Re: [patch net-next v10 00/13] net: sched: allow qdiscs to share filter block instances

[David Ahern <dsahern@gmail.com>]

On 1/16/18 7:33 AM, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@mellanox.com>
> 
> Currently the filters added to qdiscs are independent. So for example if you
> have 2 netdevices and you create ingress qdisc on both and you want to add
> identical filter rules both, you need to add them twice. This patchset
> makes this easier and mainly saves resources allowing to share all filters
> within a qdisc - I call it a "filter block". Also this helps to save
> resources when we do offload to hw for example to expensive TCAM.
> 
> So back to the example. First, we create 2 qdiscs. Both will share
> block number 22. "22" is just an identification:
> $ tc qdisc add dev ens7 ingress_block 22 ingress
>                         ^^^^^^^^^^^^^^^^
> $ tc qdisc add dev ens8 ingress_block 22 ingress
>                         ^^^^^^^^^^^^^^^^
> 
> If we don't specify "block" command line option, no shared block would
> be created:
> $ tc qdisc add dev ens9 ingress
> 
> Now if we list the qdiscs, we will see the block index in the output:
> 
> $ tc qdisc
> qdisc ingress ffff: dev ens7 parent ffff:fff1 ingress_block 22
> qdisc ingress ffff: dev ens8 parent ffff:fff1 ingress_block 22
> qdisc ingress ffff: dev ens9 parent ffff:fff1
> 
> 
> To make is more visual, the situation looks like this:
> 
>    ens7 ingress qdisc                 ens7 ingress qdisc
>           |                                  |
>           |                                  |
>           +---------->  block 22  <----------+
> 
> Unlimited number of qdiscs may share the same block.
> 
> Note that this patchset introduces block sharing support also for clsact
> qdisc:
> $ tc qdisc add dev ens10 ingress_block 23 egress_block 24 clsact
> $ tc qdisc show dev ens10
> qdisc clsact ffff: dev ens10 parent ffff:fff1 ingress_block 23 egress_block 24
> 
> 
> We can add filter using the block index:
> 
> $ tc filter add block 22 protocol ip pref 25 flower dst_ip 192.168.0.0/16 action drop
> 
> 
> Note we cannot use the qdisc for filter manipulations of shared blocks:
> 
> $ tc filter add dev ens8 ingress protocol ip pref 1 flower dst_ip 192.168.100.2 action drop
> Error: This filter block is shared. Please use the block index to manipulate the filters.
> 
> 
> We will see the same output if we list filters for ingress qdisc of
> ens7 and ens8, also for the block 22:
> 
> $ tc filter show block 22
> filter block 22 protocol ip pref 25 flower chain 0
> filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
> ...
> 
> $ tc filter show dev ens7 ingress
> filter block 22 protocol ip pref 25 flower chain 0
> filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
> ...
> 
> $ tc filter show dev ens8 ingress
> filter block 22 protocol ip pref 25 flower chain 0
> filter block 22 protocol ip pref 25 flower chain 0 handle 0x1
> ...
> 

API LGTM.

Acked-by: David Ahern <dsahern@gmail.com>