netdev - Re: [PATCH net-next 1/3] flow_offload: allow user to offload tc action to net device

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Message-ID: <a91ab46a-4325-bd98-47db-cb93989cf3c4@mojatatu.com>
Date:   Tue, 3 Aug 2021 06:14:08 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     Vlad Buslov <vladbu@...dia.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...lanox.com>, netdev@...r.kernel.org,
        oss-drivers@...igine.com, Baowen Zheng <baowen.zheng@...igine.com>,
        Louis Peens <louis.peens@...igine.com>,
        Ido Schimmel <idosch@...dia.com>,
        Jiri Pirko <jiri@...nulli.us>, Roopa Prabhu <roopa@...dia.com>
Subject: Re: [PATCH net-next 1/3] flow_offload: allow user to offload tc
 action to net device

On 2021-07-30 9:20 a.m., Simon Horman wrote:
> On Fri, Jul 30, 2021 at 06:17:18AM -0400, Jamal Hadi Salim wrote:
>> On 2021-07-28 10:46 a.m., Simon Horman wrote:

[..]

>> It still not clear to me what it means from a command line pov.
>> How do i add a rule and when i dump it what does it show?
> 
> How about we confirm that once we've implemented the feature.
> 
> But I would assume that:
> 
> * Existing methods for adding rules work as before
> * When one dumps an action (in a sufficiently verbose
>    way) the in_hw and in_hw_counter fields are displayed as they are for
>    filters.
> 
> Does that help?
> 

I think it would help a lot more to say explicitly what it actually
means in the cover letter from a tc cli pov since the subject
is about offloading actions _independently_ of filters.
I am assuming you have some more patches on top of these that
actually will actually work for that.

Example of something you could show was adding a policer,
like so:

tc actions add action ... skip_sw...

then show get or dump showing things in h/w.
And del..

And i certainly hope that the above works and it is
not meant just for the consumption of some OVS use
case.

>>> If we wish to enhance things - f.e. for debugging, which I
>>> agree is important - then I think that is a separate topic.
>>>
>>
>> My only concern is not to repeat mistakes that are in filters
>> just for the sake of symmetry. Example the fact that something
>> went wrong with insertion or insertion is still in progress
>> and you get an indication that all went well.
>> Looking at mlnx (NIC) ndrivers it does seem that in the normal case
>> the insertion into hw is synchronous (for anything that is not sw
>> only). I didnt quiet see what Vlad was referring to.
>> We have spent literally hours debugging issues where rules are being
>> offloaded thinking it was the driver so any extra info helps.
> 
> I do think there is a value to symmetry between the APIs.
> And I don't think doing so moves things in a bad direction.
> But rather a separate discussion is needed to discuss how to
> improve debuggability.
> 

Fair enough - lets have a separate discussion on debug-ability.
Maybe a new thread after reviewing Vlad's pointer.

>>> You should be able to build on the work proposed here to add what you
>>> suggest into the framework to meet these requirements for your driver work.
>>>
>>
>> Then we are good. These are the same patches you have here?
> 
> Yes.

Thanks - will review with that in mind.

cheers,
jamal