Re: [patch net-next v2 00/20] net: sched: convert cls ndo_setup_tc offload calls to per-block callbacks

[Jiri Pirko <jiri@resnulli.us>]

Tue, Oct 24, 2017 at 06:24:01PM CEST, alexander.duyck@gmail.com wrote:
>On Tue, Oct 24, 2017 at 9:01 AM, Alexander Duyck
><alexander.duyck@gmail.com> wrote:
>> On Fri, Oct 20, 2017 at 7:04 PM, David Miller <davem@davemloft.net> wrote:
>>> From: Jiri Pirko <jiri@resnulli.us>
>>> Date: Thu, 19 Oct 2017 15:50:28 +0200
>>>
>>>> This patchset is a bit bigger, but most of the patches are doing the
>>>> same changes in multiple classifiers and drivers. I could do some
>>>> squashes, but I think it is better split.
>>>>
>>>> This is another dependency on the way to shared block implementation.
>>>> The goal is to remove use of tp->q in classifiers code.
>>>>
>>>> Also, this provides drivers possibility to track binding of blocks to
>>>> qdiscs. Legacy drivers which do not support shared block offloading.
>>>> register one callback per binding. That maintains the current
>>>> functionality we have with ndo_setup_tc. Drivers which support block
>>>> sharing offload register one callback per block which safes overhead.
>>>>
>>>> Patches 1-4 introduce the binding notifications and per-block callbacks
>>>> Patches 5-8 add block callbacks calls to classifiers
>>>> Patches 9-17 do convert from ndo_setup_tc calls to block callbacks for
>>>>              classifier offloads in drivers
>>>> Patches 18-20 do cleanup
>>>
>>> Series applied.
>>
>> We are getting internal reports of regressions being seen with this
>> patch set applied. Specifically the issues below have been pointed out
>> to me. My understanding is that these issues are all being reported on
>> ixgbe:
>>
>> 1.       To offload filter into HW, the hw-tc-offload feature flag has
>> to be turned on before creating the ingress qdisc.
>>
>> Previously, this could also be turned on after the qdisc was created
>> and the filters could still be offloaded. Looks like this is because,
>> previously the offload flag was checked as a part of filter
>> integration in the classifier, and now it is checked as part of qdisc
>> creation (ingress_init). So, if no offload capability is advertised at
>> ingress qdisc creation time then hardware will not be asked to offload
>> filters later if the flag is enabled.
>>
>> 2.       Deleting the ingress qdisc fails to remove filters added in
>> HW. Filters in SW gets deleted.
>>
>> We haven’t exactly root-caused this, the changes being extensive, but
>> our guess is again something wrong with the offload check or similar
>> while unregistering the block callback (tcf_block_cb_unregister) and
>> further to the classifier (CLS_U32/CLS_FLOWER etc.) with the
>> DESTROY/REMOVE command.
>>
>> 3.       Deleting u32 filters using handle fails to remove filter from
>> HW, filter in SW gets deleted.
>>
>> Probably similar reasons, also we see some u32 specific patches as
>> well for remove nodes.
>>
>> We are still digging into this further, but wanted to put this out
>> there so we can address the issues before we go much further down this
>> path.
>>
>> Thanks.
>>
>> - Alex
>
>So a quick update. Item 3 is no longer an issue, it was a
>configuration issue on our side. So only items 1 and 2 are left to be
>addressed.

Will look at 1 and 2. Thanks for the report.

>
>Thanks.
>
>- Alex