Re: [PATCH v5 00/10] net/mlx5: per-queue Tx rate limiting via packet pacing

[Raslan Darawsheh <rasland@nvidia.com>]

Hi,


On 24/03/2026 6:50 PM, Vincent Jardin wrote:
> 
> This series adds per-queue Tx data-rate limiting to the mlx5 PMD using
> hardware packet pacing (PP), and a symmetric rte_eth_get_queue_rate_limit()
> ethdev API to read back the configured rate.
> 
> Each Tx queue can be assigned an individual rate (in Mbps) at runtime via
> rte_eth_set_queue_rate_limit(). The mlx5 implementation allocates a PP
> context per queue from the HW rate table, programs the PP index into the
> SQ via modify_sq, and relies on the kernel to share identical rates
> across PP contexts to conserve table entries. A PMD-specific API exposes
> per-queue PP diagnostics and rate table capacity.
> 
> Patch breakdown:
> 
>    01/10 doc/nics/mlx5: fix stale packet pacing documentation
>    02/10 common/mlx5: query packet pacing rate table capabilities
>    03/10 common/mlx5: extend SQ modify to support rate limit update
>    04/10 net/mlx5: add per-queue packet pacing infrastructure
>    05/10 net/mlx5: support per-queue rate limiting
>    06/10 net/mlx5: add burst pacing devargs
>    07/10 net/mlx5: add testpmd command to query per-queue rate limit
>    08/10 ethdev: add getter for per-queue Tx rate limit
>    09/10 net/mlx5: implement per-queue Tx rate limit getter
>    10/10 net/mlx5: add rate table capacity query API
> 
> Release notes for the new ethdev API and mlx5 per-queue rate
> limiting can be added to a release_26_07.rst once the file is
> created at the start of the 26.07 development cycle.
> 
> Changes since v4:
> 
>    Addressed review feedback from Stephen Hemminger and added
>    Acked-by from Viacheslav Ovsiienko on patches 03-10.
> 
>    Patch 05/10 (set rate):
>    - Add rate_kbps > UINT32_MAX bounds check before truncating to
>      the PRM rate_limit field, preventing silent overflow when HW
>      reports no maximum rate
> 
>    Patch 07/10 (testpmd + PMD query):
>    - Add NULL check on (*priv->txqs)[queue_id] before container_of()
>      in rte_pmd_mlx5_txq_rate_limit_query(), matching the pattern
>      in the setter
> 
>    Patches 03-10:
>    - Added Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> 
> Changes since v3:
> 
>    Addressed review feedback from Stephen and Slava (nvidia/Mellanox).
> 
>    Patch 02/10 (query caps):
>    - Added Acked-by: Viacheslav Ovsiienko
> 
>    Patch 03/10 (SQ modify):
>    - Define MLX5_MODIFY_SQ_IN_MODIFY_BITMASK_PACKET_PACING_RATE_LIMIT_INDEX
>      enum in mlx5_prm.h, following the MLX5_MODIFY_RQ_IN_MODIFY_xxx pattern
>    - Use read-modify-write for modify_bitmask (MLX5_GET64 | OR | MLX5_SET64)
>      instead of direct overwrite, for forward compatibility
> 
>    Patch 04/10 (PP infrastructure):
>    - Rename struct member and parameters from "rl" to "rate_limit"
>      for consistency with codebase naming style
>    - Replace MLX5_ASSERT(rate_mbps > 0) with runtime check returning
>      -EINVAL in non-debug builds
>    - Move mlx5_txq_free_pp_rate_limit() to after txq_obj_release() in
>      mlx5_txq_release() — destroy the SQ before freeing the PP index
>      it references
>    - Clarify commit message: distinct PP handle per queue (for cleanup)
>      but kernel shares the same pp_id for identical rate parameters
> 
>    Patch 05/10 (set rate):
>    - Fix obj->sq vs obj->sq_obj.sq: use obj->sq_obj.sq from the start
>      for non-hairpin queues (was introduced in patch 07 in v3, breaking
>      git bisect)
>    - Move all variable declarations to block top (sq_devx,
>      new_rate_limit)
>    - Add queue state check: reject set_queue_rate_limit if queue is not
>      STARTED (SQ not in RDY state)
>    - Update mlx5 feature matrix: Rate limitation = Y
>    - Add Per-Queue Tx Rate Limiting documentation section in mlx5.rst
>      covering DevX requirement, hardware support, rate table sharing,
>      and testpmd usage
> 
>    Patch 06/10 (burst devargs):
>    - Remove burst_upper_bound/typical_packet_size from Clock Queue
>      path (mlx5_txpp_alloc_pp_index) — Clock Queue uses WQE rate
>      pacing and does not need these parameters
>    - Update commit message and documentation accordingly
> 
>    Patch 07/10 (testpmd + PMD query):
>    - sq_obj.sq accessor change moved to patch 05 (see above)
>    - sq_devx declaration moved to block top
> 
>    Patch 08/10 (ethdev getter) — split from v3 patch 08:
>    - Split into ethdev API (this patch) and mlx5 driver (patch 09)
>    - Add rte_eth_trace_get_queue_rate_limit() trace point matching
>      the existing setter pattern
> 
>    Patch 09/10 — NEW (was part of v3 patch 08):
>    - mlx5 driver implementation of get_queue_rate_limit callback,
>      split out per Slava's request
> 
>    Patch 10/10 (rate table query):
>    - Rename struct field "used" to "port_used" to clarify per-port
>      scope
>    - Strengthen Doxygen: rate table is a global shared HW resource
>      (firmware, kernel, other DPDK instances may consume entries);
>      port_used is a lower bound
>    - Document PP sharing behavior with flags=0
>    - Note that applications should aggregate across ports for
>      device-wide visibility
> 
> Changes since v2:
> 
>    Addressed review feedback from Stephen Hemminger:
> 
>    Patch 04: cleaned redundant cast parentheses on (struct mlx5dv_pp *)
>    Patch 04: consolidated dv_alloc_pp call onto one line
>    Patch 05+08: removed redundant queue_idx bounds checks from driver
>      callbacks — ethdev layer is the single validation point
>    Patch 07: added generic testpmd command: show port <id> queue <id> rate
>    Patch 08+10: removed release notes from release_26_03.rst (targets 26.07)
>    Patch 10: use MLX5_MEM_SYS | MLX5_MEM_ZERO for heap allocation
>    Patch 10: consolidated packet_pacing_rate_table_size onto one line
> 
> Changes since v1:
> 
>    Patch 01: Acked-by Viacheslav Ovsiienko
>    Patch 04: rate bounds validation, uint64_t overflow fix, remove
>      early PP free
>    Patch 05: PP leak fix (temp struct pattern), rte_errno in error paths
>    Patch 07: inverted rte_eth_tx_queue_is_valid() check
>    Patch 10: stack array replaced with heap, per-port scope documented
> 
> Testing:
> 
>    - Build: GCC, no warnings
>    - Hardware: ConnectX-6 Dx
>    - DevX path (default): set/get/disable rate limiting verified
>    - Verbs path (dv_flow_en=0): returns -EINVAL cleanly (SQ DevX
>      object not available), no crash
> 
> Vincent Jardin (10):
>    doc/nics/mlx5: fix stale packet pacing documentation
>    common/mlx5: query packet pacing rate table capabilities
>    common/mlx5: extend SQ modify to support rate limit update
>    net/mlx5: add per-queue packet pacing infrastructure
>    net/mlx5: support per-queue rate limiting
>    net/mlx5: add burst pacing devargs
>    net/mlx5: add testpmd command to query per-queue rate limit
>    ethdev: add getter for per-queue Tx rate limit
>    net/mlx5: implement per-queue Tx rate limit getter
>    net/mlx5: add rate table capacity query API
> 
> Vincent Jardin (10):
>    doc/nics/mlx5: fix stale packet pacing documentation
>    common/mlx5: query packet pacing rate table capabilities
>    common/mlx5: extend SQ modify to support rate limit update
>    net/mlx5: add per-queue packet pacing infrastructure
>    net/mlx5: support per-queue rate limiting
>    net/mlx5: add burst pacing devargs
>    net/mlx5: add testpmd command to query per-queue rate limit
>    ethdev: add getter for per-queue Tx rate limit
>    net/mlx5: implement per-queue Tx rate limit getter
>    net/mlx5: add rate table capacity query API
> 
>   app/test-pmd/cmdline.c               |  69 ++++++++++
>   doc/guides/nics/features/mlx5.ini    |   1 +
>   doc/guides/nics/mlx5.rst             | 180 ++++++++++++++++++++++-----
>   drivers/common/mlx5/mlx5_devx_cmds.c |  23 ++++
>   drivers/common/mlx5/mlx5_devx_cmds.h |  14 ++-
>   drivers/common/mlx5/mlx5_prm.h       |   7 ++
>   drivers/net/mlx5/mlx5.c              |  46 +++++++
>   drivers/net/mlx5/mlx5.h              |  13 ++
>   drivers/net/mlx5/mlx5_testpmd.c      |  93 ++++++++++++++
>   drivers/net/mlx5/mlx5_tx.c           | 106 +++++++++++++++-
>   drivers/net/mlx5/mlx5_tx.h           |   5 +
>   drivers/net/mlx5/mlx5_txpp.c         |  90 ++++++++++++++
>   drivers/net/mlx5/mlx5_txq.c          | 149 ++++++++++++++++++++++
>   drivers/net/mlx5/rte_pmd_mlx5.h      |  74 +++++++++++
>   lib/ethdev/ethdev_driver.h           |   7 ++
>   lib/ethdev/ethdev_trace.h            |   9 ++
>   lib/ethdev/ethdev_trace_points.c     |   3 +
>   lib/ethdev/rte_ethdev.c              |  35 ++++++
>   lib/ethdev/rte_ethdev.h              |  24 ++++
>   19 files changed, 914 insertions(+), 33 deletions(-)
> 

Series applied to next-net-mlx,

Kindest regards
Raslan Darawsheh