Re: [dpdk-dev] [RFC] ethdev: add new fields for max LRO session size

[Matan Azrad <matan@mellanox.com>]

Hi All

From: Andrew Rybchenko
> On 10/18/19 7:35 PM, Ferruh Yigit wrote:
> > On 10/2/2019 2:58 PM, Thomas Monjalon wrote:
> >> 24/09/2019 14:03, Matan Azrad:
> >>> From: Ferruh Yigit
> >>>> On 9/15/2019 8:48 AM, Matan Azrad wrote:
> >>>>> Hi Ferruh
> >>>>>
> >>>>> From: Ferruh Yigit <ferruh.yigit@intel.com>
> >>>>>> On 8/29/2019 8:47 AM, Matan Azrad wrote:
> >>>>>>> It may be needed by the user to limit the LRO session packet size.
> >>>>>>> In order to allow the above limitation, add new Rx configuration
> >>>>>>> for the maximum LRO session size.
> >>>>>>>
> >>>>>>> In addition, Add a new capability to expose the maximum LRO
> >>>>>>> session size supported by the port.
> >>>>>>>
> >>>>>>> Signed-off-by: Matan Azrad <matan@mellanox.com>
> >>>>>> Hi Matan,
> >>>>>>
> >>>>>> Is there any existing user of this new field?
> >>>>> All the LRO users need it due to the next reasons:
> >>>>>
> >>>>> 1. If scatter is enabled - The dpdk user can limit the LRO session
> >>>>> size created
> >>>> by the HW by this field, if no field like that - there is no way to limit it.
> >>>>> 2. No scatter - the dpdk user may want to limit the LRO packet
> >>>>> size in order
> >>>> to save enough tail-room in the mbuf for its own usage.
> >>>>> 3. The limitation of max_rx_pkt_len is not enough - doesn't make
> >>>>> sense to
> >>>> limit LRO traffic as single packet.
> >>>> So should there be more complement patches to this RFC? To update
> >>>> the users of the field with the new field.
> >>>
> >>> We already exposed it as ABI breakage in the last deprecation notice.
> >>> We probably cannot complete it for 19.11 version, hopefully for 20.02 it
> will be completed.
> >> We won't break the ABI in 20.02.
> >> What should be done in 19.11?
> >>
> > The ask was to add code that uses new added fields, this patch only
> > adds new field to two public ethdev struct.
> >
> > @Thomas, @Andrew, if this patch doesn't goes it on this release it
> > will have to wait a year. I would like to see the implementation but
> > it is not there, what is your comment?
> 
> I don't mind to accept it in 19.11 modulo better description of what is LRO
> session length/size.


Thanks,

We can create the patch for ethdev for 19.11-RC2.

Also PMD implementation to use it for RC2.

Is it OK? (We need to break ABI as described in the deprecation notice)

Matan