Merge branch 'xdp: recycle Page Pool backed skbs built from XDP frames'

Alexander Lobakin says:

====================

Yeah, I still remember that "Who needs cpumap nowadays" (c), but anyway.

__xdp_build_skb_from_frame() missed the moment when the networking stack
became able to recycle skb pages backed by a page_pool. This was making
e.g. cpumap redirect even less effective than simple %XDP_PASS. veth was
also affected in some scenarios.
A lot of drivers use skb_mark_for_recycle() already, it's been almost
two years and seems like there are no issues in using it in the generic
code too. {__,}xdp_release_frame() can be then removed as it losts its
last user.
Page Pool becomes then zero-alloc (or almost) in the abovementioned
cases, too. Other memory type models (who needs them at this point)
have no changes.

Some numbers on 1 Xeon Platinum core bombed with 27 Mpps of 64-byte
IPv6 UDP, iavf w/XDP[0] (CONFIG_PAGE_POOL_STATS is enabled):

Plain %XDP_PASS on baseline, Page Pool driver:

src cpu Rx     drops  dst cpu Rx
  2.1 Mpps       N/A    2.1 Mpps

cpumap redirect (cross-core, w/o leaving its NUMA node) on baseline:

  6.8 Mpps  5.0 Mpps    1.8 Mpps

cpumap redirect with skb PP recycling:

  7.9 Mpps  5.7 Mpps    2.2 Mpps
                       +22% (from cpumap redir on baseline)

[0] https://github.com/alobakin/linux/commits/iavf-xdp
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 2 insertions, 17 deletions

diff --git a/net/core/xdp.c b/net/core/xdp.c
index 8c92fc553317..8d3ad315f18d 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -531,21 +531,6 @@ out:
 }
 EXPORT_SYMBOL_GPL(xdp_return_buff);
 
-/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
-void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
-{
-	struct xdp_mem_allocator *xa;
-	struct page *page;
-
-	rcu_read_lock();
-	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-	page = virt_to_head_page(data);
-	if (xa)
-		page_pool_release_page(xa->page_pool, page);
-	rcu_read_unlock();
-}
-EXPORT_SYMBOL_GPL(__xdp_release_frame);
-
 void xdp_attachment_setup(struct xdp_attachment_info *info,
 			  struct netdev_bpf *bpf)
 {
@@ -658,8 +643,8 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 	 * - RX ring dev queue index	(skb_record_rx_queue)
 	 */
 
-	/* Until page_pool get SKB return path, release DMA here */
-	xdp_release_frame(xdpf);
+	if (xdpf->mem.type == MEM_TYPE_PAGE_POOL)
+		skb_mark_for_recycle(skb);
 
 	/* Allow SKB to reuse area used by xdp_frame */
 	xdp_scrub_frame(xdpf);