Commit c15b79de authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: optimise io_req_task_work_add() 



Inline io_task_work_add() into io_req_task_work_add(). They both work
with a request, so keeping them separate doesn't make things much more
clear, but merging allows optimise it. Apart from small wins like not
reading req->ctx or not calculating @notify in the hot path, i.e. with
tctx->task_state set, it avoids doing wake_up_process() for every single
add, but only after actually done task_work_add().

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e1d767f0

fs/io_uring.c

+18 −32
Original line number Diff line number Diff line
@@ -1911,13 +1911,17 @@ static void tctx_task_work(struct callback_head *cb) 
		cond_resched();

}



static int io_task_work_add(struct task_struct *tsk, struct io_kiocb *req,

			    enum task_work_notify_mode notify)

static int io_req_task_work_add(struct io_kiocb *req)

{

	struct task_struct *tsk = req->task;

	struct io_uring_task *tctx = tsk->io_uring;

	enum task_work_notify_mode notify;

	struct io_wq_work_node *node, *prev;

	unsigned long flags;

	int ret;

	int ret = 0;



	if (unlikely(tsk->flags & PF_EXITING))

		return -ESRCH;



	WARN_ON_ONCE(!tctx);
@@ -1930,14 +1934,23 @@ static int io_task_work_add(struct task_struct *tsk, struct io_kiocb *req, 
	    test_and_set_bit(0, &tctx->task_state))

		return 0;



	if (!task_work_add(tsk, &tctx->task_work, notify))

	/*

	 * SQPOLL kernel thread doesn't need notification, just a wakeup. For

	 * all other cases, use TWA_SIGNAL unconditionally to ensure we're

	 * processing task_work. There's no reliable way to tell if TWA_RESUME

	 * will do the job.

	 */

	notify = (req->ctx->flags & IORING_SETUP_SQPOLL) ? TWA_NONE : TWA_SIGNAL;



	if (!task_work_add(tsk, &tctx->task_work, notify)) {

		wake_up_process(tsk);

		return 0;

	}



	/*

	 * Slow path - we failed, find and delete work. if the work is not

	 * in the list, it got run and we're fine.

	 */

	ret = 0;

	spin_lock_irqsave(&tctx->task_lock, flags);

	wq_list_for_each(node, prev, &tctx->task_list) {

		if (&req->io_task_work.node == node) {
@@ -1951,33 +1964,6 @@ static int io_task_work_add(struct task_struct *tsk, struct io_kiocb *req, 
	return ret;

}



static int io_req_task_work_add(struct io_kiocb *req)

{

	struct task_struct *tsk = req->task;

	struct io_ring_ctx *ctx = req->ctx;

	enum task_work_notify_mode notify;

	int ret;



	if (tsk->flags & PF_EXITING)

		return -ESRCH;



	/*

	 * SQPOLL kernel thread doesn't need notification, just a wakeup. For

	 * all other cases, use TWA_SIGNAL unconditionally to ensure we're

	 * processing task_work. There's no reliable way to tell if TWA_RESUME

	 * will do the job.

	 */

	notify = TWA_NONE;

	if (!(ctx->flags & IORING_SETUP_SQPOLL))

		notify = TWA_SIGNAL;



	ret = io_task_work_add(tsk, req, notify);

	if (!ret)

		wake_up_process(tsk);



	return ret;

}



static bool io_run_task_work_head(struct callback_head **work_head)

{

	struct callback_head *work, *next;