netdev - [PATCH RFC net-next 0/4] net: page_pool: a couple assorted optimizations

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Date: Thu, 29 Jun 2023 17:23:01 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Alexander Lobakin <aleksander.lobakin@...el.com>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
	Larysa Zaremba <larysa.zaremba@...el.com>,
	Yunsheng Lin <linyunsheng@...wei.com>,
	Alexander Duyck <alexanderduyck@...com>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	Ilias Apalodimas <ilias.apalodimas@...aro.org>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH RFC net-next 0/4] net: page_pool: a couple assorted optimizations

Here's spin off the IAVF PP series[0], with 2 runtime (hotpath) and 1
compile-time optimizations. They're based and tested on top of the
hybrid PP allocation series[1], but don't require it to work and
in general independent of it and each other.

Per-patch breakdown:
 #1: already was on the lists, but this time it's done the other way, the
     one that Alex Duyck proposed during the review of the previous series.
     Slightly reduce amount of C preprocessing by stopping including
     <net/page_pool.h> to <linux/skbuff.h> (which is included in the
     half of the kernel sources). Especially useful with the abovementioned
     series applied, as it makes page_pool.h heavier;
 #2: don't call to DMA sync externals when they won't do anything anyway
     by doing some heuristics a bit earlier (when allocating a new page),
     also was on the lists;
 #3: new, prereq to #4. Add NAPI state flag, which would indicate
     napi->poll() is running right now, so that napi->list_owner would
     point to the CPU where it's being run, not just scheduled;
 #4: new. In addition to recycling skb PP pages directly when @napi_safe
     is set, check for the flag from #3, which will mean the same if
     ->list_owner is pointing to us. This allows to use direct recycling
     anytime we're inside a NAPI polling loop or GRO stuff going right
     after it, covering way more cases than is right now.

(complete tree with [1] + this + [0] is available here: [2])

[0] https://lore.kernel.org/netdev/20230530150035.1943669-1-aleksander.lobakin@intel.com
[1] https://lore.kernel.org/netdev/20230629120226.14854-1-linyunsheng@huawei.com
[2] https://github.com/alobakin/linux/commits/iavf-pp-frag

Alexander Lobakin (4):
  net: skbuff: don't include <net/page_pool.h> to <linux/skbuff.h>
  net: page_pool: avoid calling no-op externals when possible
  net: add flag to indicate NAPI/GRO is running right now
  net: skbuff: always recycle PP pages directly when inside a NAPI loop

 drivers/net/ethernet/engleder/tsnep_main.c    |  1 +
 drivers/net/ethernet/freescale/fec_main.c     |  1 +
 .../marvell/octeontx2/nic/otx2_common.c       |  1 +
 .../ethernet/marvell/octeontx2/nic/otx2_pf.c  |  1 +
 .../ethernet/mellanox/mlx5/core/en/params.c   |  1 +
 .../net/ethernet/mellanox/mlx5/core/en/xdp.c  |  1 +
 drivers/net/wireless/mediatek/mt76/mt76.h     |  1 +
 include/linux/netdevice.h                     |  2 +
 include/linux/skbuff.h                        |  3 +-
 include/net/page_pool.h                       |  5 +-
 net/core/dev.c                                | 23 +++++--
 net/core/page_pool.c                          | 62 +++++++------------
 net/core/skbuff.c                             | 29 +++++++++
 13 files changed, 83 insertions(+), 48 deletions(-)

---
Really curious about #3. Implementing the idea correctly (this or other
way) potentially unblocks a lot more interesting stuff (besides #4).
-- 
2.41.0