On Wed, Jul 01, 2026 at 07:15:44AM -0700, Dipayaan Roy wrote:
> 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.
Were you able to track down what is the actual bottleneck on the 'broken'
platform? What is the performance of full-page approach on healthy
platforms? On changelog below you mention the frag approach 'outperforms'
the full-page one.
>
> This series depends on the following fixes now merged in net-next:
> commit 17bfe0a8c014 ("net: mana: Add NULL guards in teardown path to
> prevent panic on attach failure")
> commit 5b05aa36ee24 ("net: mana: Skip redundant detach on already-detached
> port")
>
> Changes in v11:
> - Rebased on net-next
> 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
>
>
