Re: [dpdk-dev] [RFC] ethdev: introduce Rx buffer split

[Thomas Monjalon <thomas@monjalon.net>]

12/10/2020 11:56, Slava Ovsiienko:
> Hi, Andrew
> 
> Thank you for the comments.
> 
> We have two approaches how to specify multiple segments to split Rx packets:
> 1. update queue configuration structure
> 2. introduce new rx_queue_setup_ex() routine with extra parameters.
> 
> For [1] my only actual dislike is that we would have multiple places to specify
> the pool - in rx_queue_setup() and in the config structure. So, we should
> implement some checking (if we have offload flag set we should check
> whether mp parameter is NULL and segment descriptions array pointer/size
> is provided, if no offload flag set - we must check the description array is empty). 
> 
> > @Thomas, @Ferruh: I'd like to hear what other ethdev maintainers think
> > about it.
> 
> Yes, it would be very nice to hear extra opinions. Do we think the providing
> of extra API function is worse than extending existing structure, introducing
> some conditional ambiguity and complicating the parameter compliance
> check?

Let's try listing pros and cons of each approach, so we can conclude.

1/ update queue config struct

	1.1 pro: keep same queue setup function
	1.2 con: two mempool pointers (struct or function)
	1.3 con: variable size of segment description array

2/ new queue setup function

	2.1 con: two functions for queue setup
	2.2 pro: mempool pointer is not redundant
	2.3 pro: segment description array size defined by the caller

What else I'm missing?