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

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Message-ID: <20171118171850.GA1951@nanopsycho.orion>
Date:   Sat, 18 Nov 2017 18:18:50 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>, mlxsw@...lanox.com,
        andrew@...n.ch,
        Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Simon Horman <simon.horman@...ronome.com>,
        Pieter Jansen van Vuuren 
        <pieter.jansenvanvuuren@...ronome.com>, john.hurley@...ronome.com
Subject: Re: [patch net-next v2 00/10] net: sched: allow qdiscs to share
 filter block instances

Thu, Nov 16, 2017 at 12:12:47AM CET, xiyou.wangcong@...il.com wrote:
>On Sun, Nov 12, 2017 at 7:55 AM, Jiri Pirko <jiri@...nulli.us> wrote:
>> From: Jiri Pirko <jiri@...lanox.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. 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?

That would mean you would share block 0 among all newly created qdiscs.
That is not right. By default, there should be no sharing.

>
>
>>
>> $ 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???

eth7 was ingress qdisc was assigned block 22 during the creation.
There is always 1 block assigned to one qdisc. However there might be
multiple qdiscs sharing one block. I will try to make this more clear in
the cover letter.



>
>
>>
>> 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.