[PATCH net-next 0/3] net/mlx5: enable sub-page allocations for mlx5_frag_buf

[Tariq Toukan <tariqt@nvidia.com>]

Hi,

See detailed description by Nimrod below [1].

Regards,
Tariq

[1]
This series aims to improve memory utilization for DMA-coherent
fragmented-buffer allocations on systems with large PAGE_SIZE.

Before this change, such allocations were page-granular, as they were
backed by full pages. On large-page systems this caused significant
internal waste for small objects. For example, a single 4K request
consumed an entire 64K page.

The common kernel solution for sub-page coherent DMA allocations is the
DMA pool API. However, those pools do not return pages to the system
until teardown. That behavior is not a good fit for mlx5_frag_buf
allocations, since they back interface resources (WQs and CQs).
Interfaces may be removed dynamically, so their memory footprint should
reflect live usage to avoid situations where large amounts of memory
remain tied up in pools.

This series introduces a lightweight mlx5-local pool implementation for
sub-page coherent DMA allocations, which immediately returns free
backing pages. It wires mlx5_frag_buf allocations to use these internal
pools, while keeping the mechanism reusable for other mlx5-internal
coherent DMA allocation users in follow-up work.


Nimrod Oren (3):
  net/mlx5: wire frag buf pools lifecycle hooks
  net/mlx5: add frag buf pools create/destroy paths
  net/mlx5: use internal dma pools for frag buf alloc

 .../net/ethernet/mellanox/mlx5/core/alloc.c   | 328 ++++++++++++++++--
 .../net/ethernet/mellanox/mlx5/core/main.c    |   7 +
 .../ethernet/mellanox/mlx5/core/mlx5_core.h   |   2 +
 include/linux/mlx5/driver.h                   |   9 +-
 4 files changed, 312 insertions(+), 34 deletions(-)


base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
-- 
2.44.0