netdev - Re: [net-next sample action optimization 3/3] openvswitch: Optimize sample action for the clone use cases

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Date:   Mon, 13 Mar 2017 23:20:39 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Andy Zhou <azhou@....org>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Joe Stringer <joe@....org>
Subject: Re: [net-next sample action optimization 3/3] openvswitch: Optimize
 sample action for the clone use cases

On Mon, Mar 13, 2017 at 4:39 PM, Andy Zhou <azhou@....org> wrote:
>>>> -       skb = skb_clone(skb, GFP_ATOMIC);
>>>> -       if (!skb)
>>>> -               /* Skip the sample action when out of memory. */
>>>> -               return 0;
>>>> +       if (key) {
>>>> +               err = do_execute_actions(dp, skb, key, actions, rem);
>>>> +       } else if (!add_deferred_actions(skb, orig, actions, rem)) {
>>>>
>>> We can refactor this code to avoid duplicate code all actions
>>> implementation. This way there could be single function dealing with
>>> both defered action and key fifo arrays.
>>
>> O.K. I will make the change in the next version.
>
> After looking more at it, the sample action and recirc action are different
> enough that I don't see clean ways refactor them. For example, recirc
> needs to deal with setting recirc_id.  recirc calls
> ovs_dp_process_packet, and sample calls do_execute_action.
>
Actions parameter which hints if it is recirc or sample. We can add
recic-id param and set it if it is recic case.
will this work?

>>> I am not sure if we can put sample or recirc in "may not change flow"
>>> actions list. Consider following set of actions:
>>> sample(sample(set-IP)),userpsace(),...
>>> In this case the userspace action could recieve skb with inconsistent
>>> flow due to preceding of set action nested in the sample action.
>>
>> Good catch.  Will fix.
>
> What's the objection on recirc action? It always works on clone key.

ok. recic does not have the issue.