MLX5DV_PP_ALLOC(3)

✨ mlx5dv_pp_alloc / mlx5dv_pp_free(3) ✨

okay bestie, welcome to the manual page for mlx5dv_pp_alloc and mlx5dv_pp_free, which are section 3 (library functions) of the manual. these two are your packet pacing girlies and honestly the way they just work is giving iconic. let's get into it 🎀

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💅 NAME 💅

• mlx5dv_pp_alloc — allocates a packet pacing entry ✨
• mlx5dv_pp_free — frees a packet pacing entry 🦋

🌸 SYNOPSIS 🌸

#include <infiniband/mlx5dv.h>

struct mlx5dv_pp *
mlx5dv_pp_alloc(struct ibv_context *context,
        size_t pp_context_sz,
        const void *pp_context,
        uint32_t flags);

void mlx5dv_pp_free(struct mlx5dv_pp *dv_pp);

like just look at those signatures. chef's kiss. 🔥

🫶 DESCRIPTION 🫶

so what we're doing here is creating / freeing a packet pacing entry, and that entry can be used for some device commands over the DEVX interface. that's the whole vibe. main character energy, no notes. 👑

the DEVX API enables direct access from the user space area to the mlx5 device driver — and the packet pacing information is needed for a few commands where a packet pacing index is needed. iykyk. like, not every command needs it, but the ones that do really do. 💀

🧚 ARGUMENTS 🧚

• context — the RDMA device context you're working on. plot twist: it needs to be opened with DEVX support by using mlx5dv_open_device(). so like, don't just roll up with any old context, she has to be the right one 💖
• pp_context_sz — length of the pp_context input buffer. literally just the size. no cap. 📏
• pp_context — the packet pacing context, according to the device specification. (read the spec, bestie, it's giving homework but it's important 🙈)
• flags — MLX5DV_PP_ALLOC_FLAGS_DEDICATED_INDEX: allocate a dedicated index. that's the flag. she's the only one listed, she's the moment. ⭐

and then, nested right up in there:

dv_pp

struct mlx5dv_pp {
    uint16_t index;
};

• index — the device index to be used. that's it. that's the field. 🌈

lowkey important: dv_pp is listed under ARGUMENTS in this page, so that's exactly where we're keeping her. do not move her. 😤

👑 RETURN VALUE 👑

upon success, mlx5dv_pp_alloc returns a pointer to the created packet pacing object. slay. ✨

on error, NULL will be returned and errno will be set. so like, check your return value and check your errno, bestie — she's telling you what went wrong if you actually listen 💀

🦋 SEE ALSO 🦋

• mlx5dv_open_device
• mlx5dv_devx_obj_create

go read those too, they're part of the friend group 🫶

💜 AUTHOR 💜

Yishai Hadas <yishaih@mellanox.com> — thank you for the lore, king 🎀

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and that's the whole page bestie!! this one is filed as mlx5dv_pp_alloc / mlx5dv_pp_free(3) from the source/version line of the same name — no extra date on this one, so that's all she wrote 💖✨🌸