[PATCH v3 1/3] ethdev: enable direct rearm with separate API

[Konstantin Ananyev]

Hi Feifei ,


> > > +	uint16_t *rearm_start;
> > > +	uint16_t *rearm_nb;
> >
> > I know that for Intel NICs uint16_t is sufficient, wonder would it always be
> > for other vendors?
> > Another thing to consider the case when ring position wrapping?
> > Again I know that it is not required for Intel NICs, but would it be sufficient
> > for API that supposed to be general?
> >
> For this, we re-define this structure:
> rte_eth_rxq_rearm_data {
> 	void *rx_sw_ring;
> 	uint16_t *rearm_start;
> 	uint16_t *rearm_nb;
> }
> ->
> struct *rxq_recycle_info {
> 	rte_mbuf **buf_ring;
> 	uint16_t *offset = (uint16 *)(&rq->ci);
> 	uint16_t *end;
> 	uint16_t ring_size;
> 
> }
> For the new structure, *offset is a pointer for rearm-start index of
> Rx buffer ring (consumer index). *end is a pointer for rearm-end index
> Of Rx buffer ring (producer index).
> 
> 1. we look up different pmds,  some pmds using 'uint_16t' as index size like intel PMD,
> some pmds using 'uint32_t' as index size like MLX5 or thunderx PMD.
> For pmd using 'uint32_t', rearm starts at 'buf_ring[offset & (ring_size -1)]', and 'uint16_t'
> is enough for ring size.

Sounds like a smart idea to me. 
 

> 
> 2. Good question. In general path, there is a constraint that  'nb_rearm < ring_size - rq->ci',
> This can ensure no ring wrapping in rearm. Thus in direct-rearm, we will refer to this to
> solve ring wrapping.

Should work, I think...
Just need not to forget to document it :)