netdev - [PATCH net-next 0/3] net: use skb_attempt_defer_free() in napi_consume

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Message-ID: <20251106202935.1776179-1-edumazet@google.com>
Date: Thu,  6 Nov 2025 20:29:32 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>, 
	Willem de Bruijn <willemb@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 0/3] net: use skb_attempt_defer_free() in napi_consume_skb()

There is a lack of NUMA awareness and more generally lack
of slab caches affinity on TX completion path.

Modern drivers are using napi_consume_skb(), hoping to cache sk_buff
in per-cpu caches so that they can be recycled in RX path.

Only use this if the skb was allocated on the same cpu,
otherwise use skb_attempt_defer_free() so that the skb
is freed on the original cpu.

This removes contention on SLUB spinlocks and data structures,
and this makes sure that recycled sk_buff have correct NUMA locality.

After this series, I get ~50% improvement for an UDP tx workload
on an AMD EPYC 9B45 (IDPF 200Gbit NIC with 32 TX queues).

I will later refactor skb_attempt_defer_free()
to no longer have to care of skb_shared() and skb_release_head_state().

Eric Dumazet (3):
  net: allow skb_release_head_state() to be called multiple times
  net: fix napi_consume_skb() with alien skbs
  net: increase skb_defer_max default to 128

 Documentation/admin-guide/sysctl/net.rst |  4 ++--
 net/core/hotdata.c                       |  2 +-
 net/core/skbuff.c                        | 12 ++++++++----
 3 files changed, 11 insertions(+), 7 deletions(-)

-- 
2.51.2.1041.gc1ab5b90ca-goog