RDMA_GET_SEND_COMP(3)

💖 RDMA_GET_SEND_COMP(3) 💖

okay bestie, so this is a page from the Librdmacm Programmer's Manual — yes, the rdma one, the one that makes your network go brrr 🦋 — and it's literally all about rdma_get_send_comp. Sit down, hydrate, let's get into it 💅

✨ NAME ✨

rdma_get_send_comp — retrieves a completed send, read, or write request.

like. it goes and gets your finished work request. that's the whole job. no cap 🎀

🌸 SYNOPSIS 🌸

#include <rdma/rdma_verbs.h>

int rdma_get_send_comp (struct rdma_cm_id *id, struct ibv_wc *wc);

two args, one int back. iconic behavior honestly 👑

🫶 ARGUMENTS 🫶

• id — a reference to a communication identifier to check for completions. this is the thing you're like "hey bestie, anything done in there?" about 💜
• wc — a reference to a work completion structure to fill in. it's an out-param, so it comes back stuffed with the tea ☕✨

🦋 DESCRIPTION 🦋

So what it actually does: it retrieves a completed work request for a send, an RDMA read, or an RDMA write operation. all three, same lil function, no favorites 🥰

The info about that completed request comes back to you through the wc parameter, and the wr_id in there is set to the context of the request — so you can clock which of your requests just finished, iykyk 🔥

Want the full deets on the work completion structure itself? that's not here, bestie, go see ibv_poll_cq. it's giving "read the other manpage" and honestly fair 🙈

💀 RETURN VALUE 💀

• Returns the number of returned completions (0 or 1) on success 💖 — yes, that's it, it's a very "one or nothing" kind of function, lowkey minimal, highkey fine ✨
• Returns -1 on error 😭

If an error happens, errno gets set to indicate the failure reason. always check it, bestie, don't just stare at the -1 like it owes you an explanation 💅

🌈 NOTES 🌈

okay this part is the important part, pay attention 📢

• This call polls the send completion queue associated with an rdma_cm_id.
• If a completion is not found, the call blocks until a request completes. so yeah, it'll just sit there, patiently, waiting. main character patience fr fr 🧚
• This call should only be used on rdma_cm_id's that do not share CQs with other rdma_cm_id's, and that maintain separate CQs for sends and receive completions.

Like, for real. Sharing CQs while using this? do not. that's the vibe check and you would fail it 🚫 don't do it.

👑 SEE ALSO 👑

• rdma_cm(7)
• ibv_poll_cq(3)
• rdma_get_recv_comp(3)
• rdma_post_send(3)
• rdma_post_read(3)
• rdma_post_write(3)

all your little friends, go read them too, they're a set 🎀

and that's the page!! mwah 💋 this one's from librdmacm, dated 2010-07-19, filed under RDMA_GET_SEND_COMP(3) — go poll something and slay, bestie 💖✨🦋