IBV_CREATE_CQ(3)

💖 IBV_CREATE_CQ(3) 💖

okay bestie, welcome to the Libibverbs Programmer's Manual ✨ today we're doing completion queues, and honestly? iconic behavior. this page lives in section 3, and its whole personality is ibv_create_cq and ibv_destroy_cq — making CQs and un-making them 🎀

🌸 NAME 🌸

ibv_create_cq, ibv_destroy_cq — create or destroy a completion queue (CQ) 🫶

✨ SYNOPSIS ✨

#include <infiniband/verbs.h>

struct ibv_cq *ibv_create_cq(struct ibv_context *context, int cqe,
                             void *cq_context,
                             struct ibv_comp_channel *channel,
                             int comp_vector);

int ibv_destroy_cq(struct ibv_cq *cq);

🦋 DESCRIPTION 🦋

so ibv_create_cq() is the main character here 💅 it creates a completion queue (CQ) with at least cqe entries for the RDMA device context context.

that cq_context pointer? yeah, it gets used to set the user context pointer of the CQ structure. no cap.

the channel argument is optional — if it's not NULL, then the completion channel channel will be used to return completion events 🌈 and your CQ will use the completion vector comp_vector for signaling completion events. important: comp_vector must be at least zero and less than context->num_comp_vectors. like, fr fr, don't be out here out of range 🙈

then ibv_destroy_cq() destroys the CQ cq. that's it, that's the job, she's done ✨

💀 RETURN VALUE 💀

ibv_create_cq() returns a pointer to the CQ, or NULL if the request fails 😭

ibv_destroy_cq() returns 0 on success, or the value of errno on failure (and that errno tells you the failure reason, bestie 🫶).

👑 NOTES 👑

• ibv_create_cq() may create a CQ with size greater than or equal to the requested size. so check the cqe attribute in the returned CQ for the actual size. the way that "at least" is doing heavy lifting 😭
• ibv_destroy_cq() fails if any queue pair is still associated with this CQ. so clean up your QPs first, periodt 💅

🔥 SEE ALSO 🔥

• ibv_resize_cq(3)
• ibv_req_notify_cq(3)
• ibv_ack_cq_events(3)
• ibv_create_qp(3)

💜 AUTHORS 💜

Dotan Barak <dotanba@gmail.com> 🌟

and that's the whole vibe, bestie — this page came from libibverbs, dated 2006-10-31 🎀 she's been slaying since 2006 and she's still serving. mwah 💋✨