[PATCH net-next 0/9] page_pool: a couple of assorted optimizations

[Alexander Lobakin]

That initially was a spin-off of the IAVF PP series[0], but has grown since
then a bunch. In fact, it consists of 4 semi-independent blocks:

* #1-2: Compile-time optimization. Split page_pool.h into 2 headers to
  not overbloat the consumers not needing complex inline helpers and
  then stop including it in skbuff.h at all. The first patch is also
  prereq for the whole series.
* #3: Improve cacheline locality for users of the Page Pool frag API.
* #4-6: Don't call DMA API when it would end with a no-op, i.e. on
  systems with coherent DMA and w/o enabled IOMMU or swiotlb.
* #7-9: Use direct cache recycling more aggressively, when it is safe
  obviously. In addition, make sure nobody wants to use Page Pool API
  with disabled interrupts.

Patches #1 and #8 are authored by Yunsheng and Jakub respectively, with
small modifications from my side as per ML discussions.
For the perf numbers for #3-9, please see individual commit messages.

[0] https://lore.kernel.org/netdev/20230530150035.1943669-1-aleksander.lobakin@xxxxxxxxx

Alexander Lobakin (7):
  net: skbuff: don't include <net/page_pool/types.h> to <linux/skbuff.h>
  page_pool: place frag_* fields in one cacheline
  page_pool: shrink &page_pool_params a tiny bit
  page_pool: don't use driver-set flags field directly
  page_pool: avoid calling no-op externals when possible
  net: skbuff: avoid accessing page_pool if !napi_safe when returning
    page
  net: skbuff: always try to recycle PP pages directly when in softirq

Jakub Kicinski (1):
  page_pool: add a lockdep check for recycling in hardirq

Yunsheng Lin (1):
  page_pool: split types and declarations from page_pool.h

 MAINTAINERS                                   |   3 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     |   2 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c |   2 +-
 drivers/net/ethernet/engleder/tsnep_main.c    |   1 +
 drivers/net/ethernet/freescale/fec_main.c     |   1 +
 .../net/ethernet/hisilicon/hns3/hns3_enet.c   |   1 +
 .../net/ethernet/hisilicon/hns3/hns3_enet.h   |   2 +-
 drivers/net/ethernet/marvell/mvneta.c         |   2 +-
 drivers/net/ethernet/marvell/mvpp2/mvpp2.h    |   2 +-
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   |   1 +
 .../marvell/octeontx2/nic/otx2_common.c       |   1 +
 .../ethernet/marvell/octeontx2/nic/otx2_pf.c  |   1 +
 drivers/net/ethernet/mediatek/mtk_eth_soc.c   |   1 +
 drivers/net/ethernet/mediatek/mtk_eth_soc.h   |   2 +-
 .../ethernet/mellanox/mlx5/core/en/params.c   |   1 +
 .../net/ethernet/mellanox/mlx5/core/en/trap.c |   1 -
 .../net/ethernet/mellanox/mlx5/core/en/xdp.c  |   1 +
 .../net/ethernet/mellanox/mlx5/core/en_main.c |   2 +-
 .../net/ethernet/mellanox/mlx5/core/en_rx.c   |   2 +-
 .../ethernet/mellanox/mlx5/core/en_stats.c    |   2 +-
 .../ethernet/microchip/lan966x/lan966x_fdma.c |   1 +
 .../ethernet/microchip/lan966x/lan966x_main.h |   2 +-
 drivers/net/ethernet/socionext/netsec.c       |   2 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac.h  |   2 +-
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |   1 +
 drivers/net/ethernet/ti/cpsw.c                |   2 +-
 drivers/net/ethernet/ti/cpsw_new.c            |   2 +-
 drivers/net/ethernet/ti/cpsw_priv.c           |   2 +-
 drivers/net/ethernet/wangxun/libwx/wx_lib.c   |   2 +-
 drivers/net/veth.c                            |   2 +-
 drivers/net/wireless/mediatek/mt76/mac80211.c |   1 -
 drivers/net/wireless/mediatek/mt76/mt76.h     |   1 +
 drivers/net/xen-netfront.c                    |   2 +-
 include/linux/lockdep.h                       |   7 +
 include/linux/skbuff.h                        |   3 +-
 include/net/page_pool/helpers.h               | 193 +++++++++++++++
 .../net/{page_pool.h => page_pool/types.h}    | 221 ++----------------
 include/trace/events/page_pool.h              |   2 +-
 net/bpf/test_run.c                            |   2 +-
 net/core/page_pool.c                          |  81 ++-----
 net/core/skbuff.c                             |  45 +++-
 net/core/xdp.c                                |   2 +-
 42 files changed, 325 insertions(+), 284 deletions(-)
 create mode 100644 include/net/page_pool/helpers.h
 rename include/net/{page_pool.h => page_pool/types.h} (50%)

---
Yunsheng, Jakub, pls make sure you agree with your patches that went
into the series, as both were modified :z

>From RFC v2[1]:
* drop the dependency on the hybrid allocation series (and thus the
  "RFC" prefix) -- it wasn't a strict dep and it's not in the trees yet;
* add [slightly reworked] Yunsheng's patch which splits page_pool.h into
  2 headers -- merge conflict hell otherwise.
  Also fix a typo while nobody looks (Simon);
* #3 (former #2): word the commitmsg a bit better, mention the main
  reason for the change more clearly (Ilias);
* add Jakub's hardirq assertion as a prereq for the last patch;
* #9 (former #7): add comment mentioning that the hardirq case is not
  checked due to the assertion checking it later (yes, it is illegal to
  use Page Pool with the interrupts disabled or when in TH) (Jakub);

>From RFC v1[2]:
* #1: move the entire function to skbuff.c, don't try to split it (Alex);
* #2-4: new;
* #5: use internal flags field added in #4 and don't modify driver-defined
  structure (Alex, Jakub);
* #6: new;
* drop "add new NAPI state" as a redundant complication;
* #7: replace the check for the new NAPI state to just in_softirq(), should
  be fine (Jakub).

[1] https://lore.kernel.org/netdev/20230714170853.866018-1-aleksander.lobakin@xxxxxxxxx
[2] https://lore.kernel.org/netdev/20230629152305.905962-1-aleksander.lobakin@xxxxxxxxx
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2.41.0