Re: [patch net-next v2 00/10] net: sched: allow qdiscs to share filter block instances

On Sun, Nov 12, 2017 at 7:55 AM, Jiri Pirko [off-list ref] wrote:

From: Jiri Pirko <redacted>

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. If we don't pass any
block number, a new one will be generated by kernel:

Should not block 0 by used by default if not specified by user?
Why a new one?

$ tc qdisc add dev ens7 ingress block 22
                                ^^^^^^^^
$ tc qdisc add dev ens8 ingress block 22
                                ^^^^^^^^

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 block 22
qdisc ingress ffff: dev ens8 parent ffff:fff1 block 22

Now we can add filter to any of qdiscs sharing the same block:

$ tc filter add dev ens7 ingress protocol ip pref 25 flower dst_ip 192.168.0.0/16 action drop

So you don't need to specify block 22 for this filter?
Because there is only one block???

We will see the same output if we list filters for ens7 and ens8, including stats:

$ tc -s filter show dev ens7 ingress
filter protocol ip pref 25 flower chain 0
filter protocol ip pref 25 flower chain 0 handle 0x1
  eth_type ipv4
  dst_ip 192.168.0.0/16
  not_in_hw
        action order 1: gact action drop
         random type none pass val 0
         index 1 ref 1 bind 1 installed 39 sec used 2 sec
        Action statistics:
        Sent 3108 bytes 37 pkt (dropped 37, overlimits 0 requeues 0)
        backlog 0b 0p requeues 0

Don't see which block it belongs to here.