[PATCH net-next v10 0/2] net: mana: add ethtool private flag for full-page RX buffers

[Dipayaan Roy <dipayanroy@linux.microsoft.com>]

On some ARM64 platforms with 4K PAGE_SIZE, utilizing page_pool
fragments for allocation in the RX refill path (~2kB buffer per fragment)
causes 15-20% throughput regression under high connection counts
(>16 TCP streams at 180+ Gbps). Using full-page buffers on these
platforms shows no regression and restores line-rate performance.

This behavior is observed on a single platform; other platforms
perform better with page_pool fragments, indicating this is not a
page_pool issue but platform-specific.

This series adds an ethtool private flag "full-page-rx" to let the
user opt in to one RX buffer per page:

  ethtool --set-priv-flags eth0 full-page-rx on

There is no behavioral change by default. The flag can be persisted
via udev rule for affected platforms.

This series depends on the following fixes now merged in net-next:
  17bfe0a8c014 ("net: mana: add NULL guards in teardown path to prevent panic")
  5b05aa36ee24 ("net: mana: skip redundant detach on already-detached port")

Changes in v10:
  - Rebased on net-next which now includes the prerequisite fixes.
  - Recovery logic in mana_set_priv_flags() leverages the idempotent
    mana_detach() from the merged fixes.
Changes in v9:
  - Added correct tree.
Changes in v8:
  - Fixed queue_reset_work recovery by restoring port_is_up before
    scheduling reset so the handler can properly re-attach.
  - Simplified "err && schedule_port_reset" to "schedule_port_reset".
Changes in v7:
  - Rebased onto net-next.
  - Retained private flag approach after David Wei's testing on
    Grace (ARM64) confirmed that fragment mode outperforms
    full-page mode on other platforms, validating this is a
    single-platform workaround rather than a generic issue.
Changes in v6:
  - Added missed maintainers.
Changes in v5:
  - Split prep refactor into separate patch (patch 1/2)
Changes in v4:
  - Dropping the smbios string parsing and add ethtool priv flag
    to reconfigure the queues with full page rx buffers.
Changes in v3:
  - changed u8* to char*
Changes in v2:
  - separate reading string index and the string, remove inline.

Dipayaan Roy (2):
  net: mana: refactor mana_get_strings() and mana_get_sset_count() to
    use switch
  net: mana: force full-page RX buffers via ethtool private flag

 drivers/net/ethernet/microsoft/mana/mana_en.c |  22 ++-
 .../ethernet/microsoft/mana/mana_ethtool.c    | 178 +++++++++++++++---
 include/net/mana/mana.h                       |   8 +
 3 files changed, 177 insertions(+), 31 deletions(-)

-- 
2.43.0