On 14/07/2023 14.51, Haiyang Zhang wrote:
-----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?
Today SKB "upper layers" can recycle page_pool backed packet data/page.
Just use skb_mark_for_recycle(skb), then you don't need
page_pool_release_page().
I guess, we should update the documentation, mentioning this.
--Jesper
