[PATCH v7 1/4] net/i40e: use inline prefetch function

[Tyler Retzlaff]

On Tue, Mar 26, 2024 at 11:16:10AM +0100, Morten Brørup wrote:
> > From: Tyler Retzlaff [mailto:roretzla at linux.microsoft.com]
> > Sent: Wednesday, 20 March 2024 23.02
> > 
> > Don't directly access the cacheline1 field in rte_mbuf struct for
> > prefetch instead just use rte_mbuf_prefetch_part2() to prefetch.
> > 
> > Signed-off-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
> > ---
> >  drivers/net/i40e/i40e_rxtx_vec_avx512.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/i40e/i40e_rxtx_vec_avx512.c
> > b/drivers/net/i40e/i40e_rxtx_vec_avx512.c
> > index f3050cd..0238b03 100644
> > --- a/drivers/net/i40e/i40e_rxtx_vec_avx512.c
> > +++ b/drivers/net/i40e/i40e_rxtx_vec_avx512.c
> > @@ -826,7 +826,7 @@
> >  		free[0] = m;
> >  		nb_free = 1;
> >  		for (i = 1; i < n; i++) {
> > -			rte_prefetch0(&txep[i + 3].mbuf->cacheline1);
> > +			rte_mbuf_prefetch_part2(txep[i + 3].mbuf);
> 
> @Yuying Zhang:
> If this prefetch is for m->next, I think it can be omitted if m->next is in the first cache line:
> 
> -			rte_prefetch0(&txep[i + 3].mbuf->cacheline1);
> +#if RTE_IOVA_IN_MBUF
> +			rte_mbuf_prefetch_part2(txep[i + 3].mbuf);
> +#endif

Yuying Zhang any reply here to confirm?

If not I will leave it unconditionally prefetch.

> 
> If so, it belongs in a separate patch anyway.
> 
> >  			m = rte_pktmbuf_prefree_seg(txep[i].mbuf);
> >  			if (likely(m)) {
> >  				if (likely(m->pool == free[0]->pool)) {
> > --
> > 1.8.3.1
> 
> Reviewed-by: Morten Brørup <mb at smartsharesystems.com>