NACK: [SRU][F:linux-bluefield][PATCH] UBUNTU: SAUCE: net/sched: Increase support of reclassification to 10

[Roi Dayan]

On 2021-05-10 12:48 PM, Roi Dayan wrote:
> 
> 
> On 2021-05-07 4:53 PM, Daniel Jurgens wrote:
>>> From: Tim Gardner <tim.gardner at canonical.com>
>>> Sent: Friday, May 7, 2021 7:58 AM
>>>
>>> I hate to be nit picky, but the subject line reclassify loop limit 
>>> doesn't match
>>> the value in the patch.
>>
>> My mistake there. We initially set the value to 10, but then updated 
>> it, and I missed updating the title when I squashed the fixup.
>>
>>>
>>> What kind of performance impact will this incur ? Are unclassifiable 
>>> packets
>>> common ?
>>
>> Roi, can you answer this?
>>
> 
> Hi,
> 
> For the general case there is no performance impact.
> This limit protects against accidental loop in tc rules with goto chains
> actions. so the only performance impact will only be for the case you
> actually have rules with many chains and gotos to jump between the
> chains and only for packets that will actually match the tc rules and
> do the actions.
> i.e.
> 
> chain 0: match A goto chain 1
> chain 1: match B goto chain 2
> chain 2: match C goto chain 3
> etc
> 
> This is not common but some customers doing connection tracking
> rules and changing ct zones could use more than the default.
> 
> Thanks,
> Roi
> 

I will also add that the "performance" for allowing more chains
reclassifying is vs TC not supporting this case at all.
So using openvswitch, those rules will fail to be added
to tc )and also to hw eventually when supported) and the matching
and handling of those packets will be in ovs datapath.

>>>
>>> On 5/5/21 10:43 AM, Daniel Jurgens wrote:
>>>> From: Roi Dayan <roid at nvidia.com>
>>>>
>>>> BugLink: 
>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.launchpad.net%2Fbugs%2F1927257&data=04%7C01%7Croid%40nvidia.com%7Cfb101bde402a456f8f6b08d9115f800d%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637559924127140735%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=SPKlsmNeNxi%2BA79xVy41Tl8rdk0dDJjIR6O6BdJORBQ%3D&reserved=0 
>>>>
>>>>
>>>> To support packet reclassification of more than 4 chains increase
>>>> max_reclassify_loop from 4 to 15.
>>>>
>>>> Change-Id: Ie18c37fb0255a737dc8f1b2fcf10a1163266dde6
>>>> Signed-off-by: Roi Dayan <roid at nvidia.com>
>>>> Reviewed-by: Oz Shlomo <ozsh at nvidia.com>
>>>> Signed-off-by: Daniel Jurgens <danielj at nvidia.com>
>>>> ---
>>>>    net/sched/cls_api.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index
>>>> b6e0e15..9c9afc0 100644
>>>> --- a/net/sched/cls_api.c
>>>> +++ b/net/sched/cls_api.c
>>>> @@ -1582,7 +1582,7 @@ static inline int __tcf_classify(struct 
>>>> sk_buff *skb,
>>>>                     u32 *last_executed_chain)
>>>>    {
>>>>    #ifdef CONFIG_NET_CLS_ACT
>>>> -    const int max_reclassify_loop = 4;
>>>> +    const int max_reclassify_loop = 15;
>>>>        const struct tcf_proto *first_tp;
>>>>        int limit = 0;
>>>>
>>>>
>>>
>>> -- 
>>> -----------
>>> Tim Gardner
>>> Canonical, Inc