rpma_write(3)

✨ rpma_write — bestie edition ✨

okay so you're here for rpma_write(3) from the RPMA Programmer's Manual and honestly? you came to the right place 💖 this is the one that makes your local memory yeet itself over to the remote side. let's get into it.

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🌸 NAME 🌸

rpma_write — initiate the write operation

like, it starts the whole thing. it's giving main character energy for your data transfer 🦋

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⭐ SYNOPSIS ⭐

#include <librpma.h>

struct rpma_conn;
struct rpma_mr_local;
struct rpma_mr_remote;
int rpma_write(struct rpma_conn *conn,
                struct rpma_mr_remote *dst, size_t dst_offset,
                const struct rpma_mr_local *src, size_t src_offset,
                size_t len, int flags, const void *op_context);

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💅 DESCRIPTION 💅

so rpma_write() initiates transferring data from the local memory to the remote memory. that's it, that's the whole vibe ✨

and listen — to write a 0 bytes message, set src and dst to NULL and src_offset, dst_offset and len to 0. yes bestie, a zero-byte message is a real thing, it's valid, it's iconic, we respect it 🎀

the attribute flags set the completion notification indicator, which is basically "when do you wanna hear back from me":

• RPMA_F_COMPLETION_ON_ERROR — generate the completion on error
• RPMA_F_COMPLETION_ALWAYS — generate the completion regardless of result of the operation.

and op_context? it gets returned in the wr_id field of the completion (that's a struct ibv_wc btw) so you can tell which operation just finished. it's like a little name tag for your write 🏷️

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💖 RETURN VALUE 💖

rpma_write() returns 0 on success or a negative error code on failure. no cap. if you see a negative number, something went sideways 😭

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🔥 ERRORS 🔥

rpma_write() can fail with the following errors, and honestly she's dramatic about it:

• RPMA_E_INVAL — conn == NULL || flags == 0
• RPMA_E_INVAL — dst == NULL && (src != NULL || src_offset != 0 || dst_offset != 0 || len != 0)
• RPMA_E_INVAL — src == NULL && (dst != NULL || src_offset != 0 || dst_offset != 0 || len != 0)
• RPMA_E_PROVIDER — ibv_post_send(3) failed

ngl those first three are all about not mixing NULL pointers with nonzero offsets/lengths, so like... read them carefully before you come for me 🙈

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👑 SEE ALSO 👑

rpma_conn_req_connect(3), rpma_mr_reg(3), rpma_mr_remote_from_descriptor(3), librpma(7) and https://pmem.io/rpma/

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and that's the whole page bestie, slay 💅✨🦋

this was brought to you by the RPMA crew, dated 01 April 2024, and yeah the date is real, not a prank, iykyk 🎀💖🌸