On Wed, 11 Mar 2026 00:26:47 +0100 Vincent Jardin <[email protected]> wrote:
> Add mlx5_txq_rate_limit structure and alloc/free helpers for > per-queue data-rate packet pacing. Each Tx queue can now hold > its own PP (Packet Pacing) index allocated via mlx5dv_pp_alloc() > with MLX5_DATA_RATE mode. > > mlx5_txq_alloc_pp_rate_limit() converts Mbps to kbps for the PRM > rate_limit field and allocates a dedicated PP index from the HW > rate table. mlx5_txq_free_pp_rate_limit() releases it. > > The existing Clock Queue path (sh->txpp.pp / sh->txpp.pp_id) is > untouched — it uses MLX5_WQE_RATE for per-packet scheduling, > while per-queue rate limiting uses MLX5_DATA_RATE. > > PP index cleanup is added to mlx5_txq_release() to prevent leaks > when queues are destroyed. > > Supported hardware: > - ConnectX-6 Dx: per-SQ rate via packet_pacing_rate_limit_index > - ConnectX-7/8: same mechanism, plus wait-on-time coexistence > - BlueField-2/3: same PP allocation support > > Not supported: > - ConnectX-5: packet_pacing exists but MLX5_DATA_RATE mode may > not be available on all firmware versions > - ConnectX-4 Lx and earlier: no packet_pacing capability > > Signed-off-by: Vincent Jardin <[email protected]> For better type safety, void * pointers should be avoided. In this patch, struct mlx5_txq_rate_limit stores the PP context as void *pp. This opaque pointer hides the type and makes the code harder for static analysis. Use the actual type (struct mlx5dv_pp *) behind the HAVE_MLX5DV_PP_ALLOC guard so the cast at ((struct mlx5dv_pp *)(rl->pp))->index becomes a direct member access. Minor nit: The line break in the dv_alloc_pp call hurts readability — the function call, its arguments, and the NULL check would be clearer on fewer lines:  rl->pp = mlx5_glue->dv_alloc_pp(sh->cdev->ctx, sizeof(pp), &pp, 0); if (rl->pp == NULL) {
