Commit f28c240e authored by Hao Xu's avatar Hao Xu Committed by Jens Axboe
Browse files

io_uring: batch completion in prior_task_list 



In previous patches, we have already gathered some tw with
io_req_task_complete() as callback in prior_task_list, let's complete
them in batch while we cannot grab uring lock. In this way, we batch
the req_complete_post path.

Signed-off-by: default avatarHao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20211208052125.351587-1-haoxu@linux.alibaba.com


Reviewed-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a37fae8a

fs/io_uring.c

+60 −11
Original line number Diff line number Diff line
@@ -2225,7 +2225,49 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked) 
	percpu_ref_put(&ctx->refs);

}



static void handle_tw_list(struct io_wq_work_node *node, struct io_ring_ctx **ctx, bool *locked)

static inline void ctx_commit_and_unlock(struct io_ring_ctx *ctx)

{

	io_commit_cqring(ctx);

	spin_unlock(&ctx->completion_lock);

	io_cqring_ev_posted(ctx);

}



static void handle_prev_tw_list(struct io_wq_work_node *node,

				struct io_ring_ctx **ctx, bool *uring_locked)

{

	if (*ctx && !*uring_locked)

		spin_lock(&(*ctx)->completion_lock);



	do {

		struct io_wq_work_node *next = node->next;

		struct io_kiocb *req = container_of(node, struct io_kiocb,

						    io_task_work.node);



		if (req->ctx != *ctx) {

			if (unlikely(!*uring_locked && *ctx))

				ctx_commit_and_unlock(*ctx);



			ctx_flush_and_put(*ctx, uring_locked);

			*ctx = req->ctx;

			/* if not contended, grab and improve batching */

			*uring_locked = mutex_trylock(&(*ctx)->uring_lock);

			percpu_ref_get(&(*ctx)->refs);

			if (unlikely(!*uring_locked))

				spin_lock(&(*ctx)->completion_lock);

		}

		if (likely(*uring_locked))

			req->io_task_work.func(req, uring_locked);

		else

			__io_req_complete_post(req, req->result, io_put_kbuf(req));

		node = next;

	} while (node);



	if (unlikely(!*uring_locked))

		ctx_commit_and_unlock(*ctx);

}



static void handle_tw_list(struct io_wq_work_node *node,

			   struct io_ring_ctx **ctx, bool *locked)

{

	do {

		struct io_wq_work_node *next = node->next;
@@ -2246,31 +2288,38 @@ static void handle_tw_list(struct io_wq_work_node *node, struct io_ring_ctx **ct 


static void tctx_task_work(struct callback_head *cb)

{

	bool locked = false;

	bool uring_locked = false;

	struct io_ring_ctx *ctx = NULL;

	struct io_uring_task *tctx = container_of(cb, struct io_uring_task,

						  task_work);



	while (1) {

		struct io_wq_work_node *node;

		struct io_wq_work_node *node1, *node2;



		if (!tctx->prior_task_list.first &&

		    !tctx->task_list.first && locked)

		if (!tctx->task_list.first &&

		    !tctx->prior_task_list.first && uring_locked)

			io_submit_flush_completions(ctx);



		spin_lock_irq(&tctx->task_lock);

		node= wq_list_merge(&tctx->prior_task_list, &tctx->task_list);

		if (!node)

		node1 = tctx->prior_task_list.first;

		node2 = tctx->task_list.first;

		INIT_WQ_LIST(&tctx->task_list);

		INIT_WQ_LIST(&tctx->prior_task_list);

		if (!node2 && !node1)

			tctx->task_running = false;

		spin_unlock_irq(&tctx->task_lock);

		if (!node)

		if (!node2 && !node1)

			break;



		handle_tw_list(node, &ctx, &locked);

		if (node1)

			handle_prev_tw_list(node1, &ctx, &uring_locked);



		if (node2)

			handle_tw_list(node2, &ctx, &uring_locked);

		cond_resched();

	}



	ctx_flush_and_put(ctx, &locked);

	ctx_flush_and_put(ctx, &uring_locked);

}



static void io_req_task_work_add(struct io_kiocb *req, bool priority)
@@ -2759,7 +2808,7 @@ static void io_complete_rw(struct kiocb *kiocb, long res) 
		return;

	req->result = res;

	req->io_task_work.func = io_req_task_complete;

	io_req_task_work_add(req, true);

	io_req_task_work_add(req, !!(req->ctx->flags & IORING_SETUP_SQPOLL));

}



static void io_complete_rw_iopoll(struct kiocb *kiocb, long res)