On Thu, 12 Mar 2026 23:01:11 +0100 Vincent Jardin <[email protected]> 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 > dedicated PP index per rate from the HW rate table, programs it into the > SQ via modify_sq, and shares identical rates across queues to conserve > table entries. A PMD-specific API exposes per-queue PP diagnostics and > rate table capacity. > > Patch breakdown: > > 1. doc/nics/mlx5: fix stale packet pacing documentation > 2-3. common/mlx5: query PP capabilities and extend SQ modify > 4-6. net/mlx5: per-queue PP infrastructure, rate_limit callback, > burst pacing devargs (tx_burst_bound, tx_typical_pkt_sz) > 7. net/mlx5: testpmd command to query per-queue rate state > 8. ethdev: add rte_eth_get_queue_rate_limit() symmetric getter > + testpmd "show port <id> queue <id> rate" command > 9. net/mlx5: rate table capacity query API > > Usage with testpmd: > set port 0 queue 0 rate 1000 > set port 0 queue 1 rate 5000 > set port 0 queue 0 rate 0 # disable > show port 0 queue 0 rate # generic ethdev query > mlx5 port 0 txq 0 rate show # mlx5 PMD-specific query > > Changes since v2: > > Patch 4 (per-queue packet pacing infrastructure): > - Folded "share pacing rate table entries across queues" into > this patch (was a separate patch in v2) > > Patch 5 (support per-queue rate limiting): > - Remove redundant queue_idx >= nb_tx_queues check (ethdev > layer already validates before calling the PMD callback) > > Patch 8 (ethdev getter): > - Add testpmd "show port <id> queue <id> rate" command > in app/test-pmd/cmdline.c using rte_eth_get_queue_rate_limit() > - Drop release notes (targeting 26.07, not 26.03) > - Remove redundant queue_idx bounds check from mlx5 getter > > Patch 9 (rate table capacity query): > - Use MLX5_MEM_SYS flag in mlx5_malloc() for system memory > - Minor code style cleanups (line wrapping, cast formatting) > > Changes since v1: > > Addressed review feedback from Stephen Hemminger's AI: > > Patch 4 (per-queue packet pacing infrastructure): > - Validate rate_mbps against HCA packet_pacing_min_rate and > packet_pacing_max_rate bounds; return -ERANGE on out-of-range > - Widen rate_kbps from uint32_t to uint64_t to prevent > overflow on rate_mbps * 1000 > - Remove early mlx5_txq_free_pp_rate_limit() call from the > allocator (moved to caller, see patch 5) > > Patch 5 (support per-queue rate limiting): > - Fix PP index leak on modify_sq failure: allocate new PP into a > temporary struct mlx5_txq_rate_limit; only swap into txq_ctrl->rl > after modify_sq succeeds. On failure the old PP context stays intact. > - Set rte_errno = -ret before returning errors from both the > disable (tx_rate=0) and enable paths > > Patch 7 (testpmd command to query per-queue rate limit): > - Fix inverted rte_eth_tx_queue_is_valid() return value check: > was "if (rte_eth_tx_queue_is_valid(...))" (accepts invalid queues), > changed to "if (rte_eth_tx_queue_is_valid(...) != 0)" > > Patch 9 (rate table capacity query, was patch 10 in v1): > - Replace uint16_t seen[RTE_MAX_QUEUES_PER_PORT] (2 KB stack array) > with heap-allocated mlx5_malloc(priv->txqs_n, ...) + mlx5_free() > - Add early return when txqs == NULL || txqs_n == 0 > - Document in the API Doxygen that "used" reflects only the queried > port's queues; other ports on the same device may also consume > rate table entries > - Add -ENOMEM to documented return values > > Hardware tested: > - ConnectX-6 Dx (packet pacing with MLX5_DATA_RATE) > > Vincent Jardin (9): > 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: add rate table capacity query API > > app/test-pmd/cmdline.c | 69 +++++++++++++ > doc/guides/nics/mlx5.rst | 125 ++++++++++++++++++------ > drivers/common/mlx5/mlx5_devx_cmds.c | 20 ++++ > drivers/common/mlx5/mlx5_devx_cmds.h | 14 ++- > 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 | 104 +++++++++++++++++++- > drivers/net/mlx5/mlx5_tx.h | 5 + > drivers/net/mlx5/mlx5_txpp.c | 85 ++++++++++++++++ > drivers/net/mlx5/mlx5_txq.c | 141 +++++++++++++++++++++++++++ > drivers/net/mlx5/rte_pmd_mlx5.h | 62 ++++++++++++ > lib/ethdev/ethdev_driver.h | 7 ++ > lib/ethdev/rte_ethdev.c | 28 ++++++ > lib/ethdev/rte_ethdev.h | 24 +++++ > 15 files changed, 802 insertions(+), 33 deletions(-) > Only minor things left to address. Error (1): Patch 5 — git bisect breakage with obj->sq vs obj->sq_obj.sq. Patch 5 accesses the SQ DevX object via txq_ctrl->obj->sq, which is the hairpin union member. For non-hairpin DevX/HWS queues the correct field is obj->sq_obj.sq. Patch 7 fixes this, but patch 5 is broken as submitted — each commit needs to be independently correct for bisect. The sq_obj.sq change should be moved into patch 5. Warnings (3): Patch 8: mlx5_get_queue_rate_limit() doesn't bounds-check queue_idx before array access (the ethdev layer does, but the set path checks it too — inconsistent). Also missing release notes for the new ethdev API, and the new eth_dev_ops member needs ethdev maintainer agreement. Patch 9: The "used" count is per-port but the API name suggests device-wide — consider renaming or iterating all ports on the shared context.
