Re: [dpdk-dev] KNI interface

[Harish Patil <harish.patil@qlogic.com>]

>KNI is mainly designed for exception path or control plane packets that
>need to be pushed
>to Linux TCP/IP packets in the kernel. You can push all the packets that
>DPDK PMD received
>in the user space via KNI to kernel, but majority of them will be dropped
>for two reasons: 1) skb
>allocation/free and memory copy between mbuf and skb 2) slow TCP/IP
>stack.
>In terms of how to use it, basically it is user responsibility to do
>simple flow classification using
>5-tuple in DPDK application, and push exception packets or control
>packets to KNI queues, in other
>words, to slow path. While DPDK user space still process fast path
>packets.

Thanks for the clarification, Bruce/Danny.

Few follow-on questions:

i) Does the generic 5-tuple flow classification that the DPDK provides
would cover all possible packet types (e.g. Q-Q/tunneled/vxlan etc)?.
Manual packet parsing by the poll mode driver would be a daunting task by
itself.

ii) How would the forwarding/routing changes in the kernel pushed to (or
synchronized with) the DPDK L2/L3 application?

iii) Can we just live with [base DPDK + linux TCP/IP stack], without
third-party modules, to achieve full networking stack functionality at
least in a non-virtualized environment ?


>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Harish Patil
>> Sent: Saturday, July 19, 2014 8:09 AM
>> To: dev@dpdk.org
>> Subject: [dpdk-dev] KNI interface
>>
>> Hello dpdk-dev,
>> Went thru’ couple of documentation but not very clear to me. Does using
>> KNI means handing over all the packets received/transmitted by the poll
>> mode driver to the linux stack or can it be controlled for the control
>> packets only ? What is the KNI use-case (besides ethtool) and what are
>>the
>> best options/choices/strategy to use poll mode driver for data path and
>> linux for control plane operations ?
>>
>> Thanks,
>> Harish
>>
>>
>>
>>
>>
>>
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