RE: [PATCH net-next] net: mana: Add page pool for RX buffers

[Haiyang Zhang]

> -----Original Message-----
> From: Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>
> On 14/07/2023 05.53, Jakub Kicinski wrote:
> > On Thu, 13 Jul 2023 14:48:45 +0000 Haiyang Zhang wrote:
> >> Add page pool for RX buffers for faster buffer cycle and reduce CPU
> >> usage.
> >>
> >> Get an extra ref count of a page after allocation, so after upper
> >> layers put the page, it's still referenced by the pool. We can reuse
> >> it as RX buffer without alloc a new page.
> >
> > Please use the real page_pool API from include/net/page_pool.h
> > We've moved past every driver reinventing the wheel, sorry.
> 
> +1
> 
> Quoting[1]: Documentation/networking/page_pool.rst
> 
>   Basic use involves replacing alloc_pages() calls with the
> page_pool_alloc_pages() call.
>   Drivers should use page_pool_dev_alloc_pages() replacing
> dev_alloc_pages().
 
Thank Jakub and Jesper for the reviews.
I'm aware of the page_pool.rst doc, and actually tried it before this 
patch, but I got lower perf. If I understand correctly, we should call 
page_pool_release_page() before passing the SKB to napi_gro_receive().

I found the page_pool_dev_alloc_pages() goes through the slow path, 
because the page_pool_release_page() let the page leave the pool.

Do we have to call page_pool_release_page() before passing the SKB 
to napi_gro_receive()? Any better way to recycle the pages from the 
upper layer of non-XDP case?

Thanks,
- Haiyang