[dpdk-users] Round-robin packet distribution

[Filip Janiszewski]

Hi,


> Start from reading https://doc.dpdk.org/guides/prog_guide/rte_flow.html
> eg Table 12.22
> 

And here's the painful news, the Mellanox cards we're using do not
support RAW flow items, which means I can't make use of the features
explained in the table 12.22


> But in my mind, as already mentioned by someone else, I think that
> randomly spreading packets across different cores
> might not be a good idea.
> 
> If you want packets to be spread across all cores in deterministic but
> even way then easiest would be to use
> RSS over IP / UDP. As a second iteration I would use Flow director API +
> IP / UDP rules *without* RAW items.
> 

Can you elaborate a bit? Perhaps there's some example somewhere on git
we can use as reference?

Thanks

> Paweł
> 
> On 24.08.2020 12:07, Tom Barbette wrote:
>> He means bytes.
>>
>> I think some drivers only allow the flexible bytes to start after the
>> actual matching though, eg TCP header. So check for that. I'd contact
>> Sprayer authors to ask how they did it if I were you.
>>
>> Do you have a specific NIC in mind? Mellanox's ones are pretty
>> powerful, it may be worth it to have a PM-to-PM meeting asking about
>> feature, or CC one of the maintainer. Devs do not always look at all
>> mails.
>>
>> Cheers,
>>
>> Tom
>>
>> Le 18/08/2020 à 16:27, Filip Janiszewski a écrit :
>>> Do you mean bit or bytes? 'b' refers to bit, maybe you meant bytes? As
>>> for the network traffic type, we're capturing financial market traffic
>>> over TCP/UDP, nothing really fancy.
>>>
>>> Thanks
>>>
>>> Il 8/18/20 3:50 PM, Pawel Wodkowski ha scritto:
>>>> Flexible payload matching (aka RAW in flow API) works up to first
>>>> 64b of
>>>> the
>>>> packet - at least in e1000, ixgbe and i40e.
>>>>
>>>> It will be easier if you can provide some details about you network
>>>> traffic.
>>>>
>>>> Paweł
>>>>
>>>> On 18.08.2020 14:40, Filip Janiszewski wrote:
>>>>> Hi,
>>>>>
>>>>> We had a look at that, and decided that it might be a bit too
>>>>> complicated to implement in our SW and will not work in a
>>>>> performant way
>>>>> as we might wish, ideally we're looking for a simple approach even if
>>>>> not ideal..
>>>>>
>>>>> So, I was wondering if we can get at least a "fair" distribution (no
>>>>> round robin) using rte flow? And BTW, is it even possible to access
>>>>> the
>>>>> checksum from this API using for example the pattern matching with an
>>>>> offset that points to the proper byte location in the packet? (It
>>>>> seems
>>>>> it can't be done without modification to the driver..)
>>>>>
>>>>> Thanks
>>>>>
>>>>> Il 7/25/20 10:28 AM, Tom Barbette ha scritto:
>>>>>> Hi Filip,
>>>>>>
>>>>>> This is not possible, but you may use the idea of Sprayer
>>>>>> (http://www.gta.ufrj.br/ftp/gta/TechReports/SCC18d.pdf) to dispatch
>>>>>> packets randomly (use RSS on the checksum).
>>>>>>
>>>>>> However, in our paper RSS++
>>>>>> (https://www.diva-portal.org/smash/get/diva2:1371780/FULLTEXT01.pdf)
>>>>>> we
>>>>>> show it's nearly always a bad idea because you'll have to share
>>>>>> state,
>>>>>> and even for "stateless" function, that leads to a very bad
>>>>>> locality in
>>>>>> a firewall as the same rules have to be fetched to L1 to all cores at
>>>>>> the same time when you receive a burst of similar packets.
>>>>>>
>>>>>> Tom
>>>>>>
>>>>>> Le 24/07/2020 à 12:05, Filip Janiszewski a écrit :
>>>>>>> Hi,
>>>>>>>
>>>>>>> Is there a way in DPDK to configure the NIC to distribute the
>>>>>>> incoming
>>>>>>> packets to multiple queues in a round robin fashion? Without taking
>>>>>>> into
>>>>>>> account the payload/headers or type of packet, just plain round
>>>>>>> robin
>>>>>>> distribution to multiple queues.
>>>>>>>
>>>>>>> I'm struggling to obtain a fair mechanism using RSS, perhaps the
>>>>>>> rte_flow API can do the trick? Any other suggestion?
>>>>>>>
>>>>>>> Thanks
>>>>>>>
>>
> 

-- 
BR, Filip
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