Re: [PATCH net-next v8 3/3] net: ethernet: ti: am65-cpsw: Add minimal XDP support

[Julien Panis]

On 4/10/24 17:02, Jakub Kicinski wrote:
> On Wed, 10 Apr 2024 16:02:00 +0200 Julien Panis wrote:
> > > You shouldn't build the skb upfront any more. Give the page to the HW,
> > > once HW sends you a completion - build the skbs. If build fails
> > > (allocation failure) just give the page back to HW. If it succeeds,
> > > however, you'll get a skb which is far more likely to be cache hot.
> > Not sure I get this point.
> >
> > "Give the page to the HW" = Do you mean that I should dma_map_single()
> > a full page (|PAGE_SIZE|) in am65_cpsw_nuss_rx_push() ?
> Yes, I think so. I think that's what you effectively do now anyway,
> you just limit the len and wrap it in an skb. But
> am65_cpsw_nuss_rx_push() will effectively get that page back from
> skb->data and map it.

That's much better indeed, with the implementation you suggest: 600 Mbits/sec
instead of 500. I did not expect such improvement.
I'll send a new version when I finish retesting.