Commit 6ec9afc7 authored Jun 23, 2023 by Pavel Begunkov Committed by Jens Axboe Jun 23, 2023

io_uring: remove io_free_req_tw



Request completion is a very hot path in general, but there are 3 places
that can be doing it: io_free_batch_list(), io_req_complete_post() and
io_free_req_tw().

io_free_req_tw() is used rather marginally and we don't care about it.
Killing it can help to clean up and optimise the left two, do that by
replacing it with io_req_task_complete().

There are two things to consider:
1) io_free_req() is called when all refs are put, so we need to reinit
   references. The easiest way to do that is to clear REQ_F_REFCOUNT.
2) We also don't need a cqe from it, so silence it with REQ_F_CQE_SKIP.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/434a2be8f33d474ad888ce1c17fe5ea7bbcb2a55.1687518903.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 247f97a5

io_uring/io_uring.c

+5 −18

Original line number	Diff line number	Diff line
		@@ -1121,26 +1121,13 @@ static inline void io_dismantle_req(struct io_kiocb *req)
		io_put_file(req->file);
		}

		static __cold void io_free_req_tw(struct io_kiocb req, struct io_tw_state ts)
		{
		struct io_ring_ctx *ctx = req->ctx;

		if (req->rsrc_node) {
		io_tw_lock(ctx, ts);
		io_put_rsrc_node(ctx, req->rsrc_node);
		}
		io_dismantle_req(req);
		io_put_task_remote(req->task, 1);

		spin_lock(&ctx->completion_lock);
		wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
		ctx->locked_free_nr++;
		spin_unlock(&ctx->completion_lock);
		}

		__cold void io_free_req(struct io_kiocb *req)
		{
		req->io_task_work.func = io_free_req_tw;
		/* refs were already put, restore them for io_req_task_complete() */
		req->flags &= ~REQ_F_REFCOUNT;
		/* we only want to free it, don't post CQEs */
		req->flags \|= REQ_F_CQE_SKIP;
		req->io_task_work.func = io_req_task_complete;
		io_req_task_work_add(req);
		}